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If you have any questions you want answered, feel free to drop me a note. If you’ve got a question, chances are, there are lots of others out there with the same question. So ask away!
Can you talk about the pros and cons of different insulation materials?
Hope your well. Thanks for including me on your e-mail list. I like your blog and could of used it years ago.
On my 16 seer heat pump I can’t stand the fan revving up and down constantly. If I knew this I would of never got a 2 stage variable speed unit. It’s loud enough to wake you up at night. Starts at high, slows down for 30 seconds then high again. Was told it may be the thermostat and may have to upgrade. They say it is all about comfort but really feel it is defective. They said if I upgrade to $500 thermostat it may help?
That sounds defective to me. These systems typically ramp up slowly so that they’re unobtrusive. Not to say that they’re silent, but they should be much “smoother” sounding than a conventional single speed unit.
The ramping cycle is handled by the controller electronics in the unit, so that should be independent of the thermostat. However, it is possible that the thermostat is doing something odd with the multiple stages. Normally, they’ll turn on stage one, let it run a bit and then if it can’t satisfy the call for heat, it will ramp up to stage 2. If that doesn’t work, it will turn on the auxiliary heat strips. But this should all be very smooth.
One thing that could be making it run less than optimally is if you program your thermostat to use setbacks of more than a couple degrees. Heat pumps like to be run at a constant temperature with only changes of one or two degrees. If you have it programmed to, for example, set the temperature to 65 during the day when you’re not home, then up to 70 for bedtime, then it will most likely force it to high speed or auxiliary heat, making it run inefficiently.
You could also have an issue with how the refrigerant lines run through the wall. I have this problem – my lines are strapped to the wall outside my bedroom so that when the system comes on, there’s a loud buzzing as the vibrations are transmitted right into the wall. Very annoying.
One question – is the noise coming from the outside unit or the air handler?
[...] Ask Ted! [...]
Ted, I have oil fired forced hot water heat and indirect domestic hot water. In the basement and on the first floor I also have two chest freezers, a refrigerator/freezer, a dehumidifier, and two window air conditioners. Although I currently get domestic water from a main in the street, I also have two dug wells piped into the cellar (i.e. a lot of cool water) and a good site for solar thermal panels (i.e. a source of hot water). It seems to me that with a little plumbing there ought to be a clever way to make all the things that are hot but trying to be cold and all the things that are cold but trying to be hot work together to reduce my energy bill. My first thought was pipe cool water to the radiators of the freezers and dehumidifier, but would cooling their radiators make the compressors any more efficiently? My second thought was why not a sterling engine to generate electricity and preheat the domestic hot water. The WhisperGen system burns natural gas, and low hot-end temperatures are said to increase the size of a sterling engine, but in my cellar space isn’t an issue. Thoughts? Too bad you don’t live closer, we could tinker.
Ah tinkering. That would be fun!
You’ve got a lot going on there and your thoughts about using systems together instead of opposing one another makes a lot of sense. I’ve always wondered about utilizing waste heat from refrigerators to pre-heat water, for example. You’d have to be a bit clever about it to optimize the operation. For example, turn on the compressor to pre-heat the water at the same time as you’re taking a shower so that cold water is coming through the heat exchanger. Otherwise, you’d actually be less efficient than normal because it would be trying to extract heat into hot water. So there are definitely some nuances that would have to be considered.
The Stirling engine idea is always intriguing. My issue is that, for residential applications, the “waste heat” issue is much lower than in industrial apps where it’s a huge problem. Because of that, the benefit of reclaiming the waste heat in residences is reduced. I would probably just go solar-thermal since that’s well developed and highly efficient. Anything with off-the-shelf parts is going to make your life easier in the long run.
Have you looked into the wastewater heat recovery systems? I would have installed one of these but my drain line isn’t far enough below the bathroom and you really need the drain to be going out down low in the house. http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=13040
Isn’t cellulose flammable? I know of at least one instance where the fireproofing compound on cellulose was washed away because of water damage and an electrical fire started from wires damaged by the same water damage. What about fiber metal insulation, I saw it on How It’s Made?
I’ll have to look into the cellulose flammability issue. I do know the green building community has wholeheartedly adopted it for many projects so perhaps it was a shortcoming of an older version of the fireproofing. Much cellulose is installed using a “damp spray” method these days, so I can’t imagine that the borates would come off however it’s manufactured today.
The last research report I saw showed that the house have a vastly improved fireproofing capacity, but much of that was because the fire couldn’t more through wall cavities, since it typically travels along air currents and it would just snuff out in the cellulose. However, if exposed to enough heat, they say it will burn. It has fire retardant properties, not fire proof.
Check into Roxsul- discovered it when our cabin was done 3 years ago and the stuff is incredible. For our home to be done in roxsul, it was only a 25% increase in insulation cost, but the non-flamability and r-value together were the drving factor. Around here, many of the trades use it for fireproofing at required spaces. Additionally, the wood stove and chimmney penetrations can be insulated right to the object- no need for the air space as with fiberglass or other insulations. Just cant put tight to can lights or other devices that air space to dispurse heat. Hope this helps…
Roxul is great stuff! Most of the Green builders I know love it as a replacement for fiberglass. It can be hard to get, but if you’re persistent, you can usually find a supplier to special order it for you.
I had a home energy audit 2 years ago and among the many things done as a result wad dense packing of cathedral ceiling with cellulose. I have no soffit vents. I have been talking to roofing contractors who all seem to be of the opinion that I need to add soffit ventilation. I have a ridge vent when my previous roof was applied approx, 17 years ago. I live near Albany, NY.
I read your article entitled “Cathedral Ceilings – Problems and Solutions where you state “I have no problem with ridge vents IF they’re implemented along with a proper amount of soffit vents. I have huge problems with ridge vents when installed without soffit vents.”
As I am going to have a new roof installed, this is the time for me to handle the cathedral ceiling properly.
What do you suggest?
If you had the roof dense packed, then adding soffit vents isn’t going to do anything for you. A dense-packed ceiling is supposed to be sealed because the cellulose dense packed should be stopping air movement.
However, you have to be really careful. It depends on the interior construction of your ceiling also.
When you say you’re having a new roof installed, are you actually removing all the roof sheathing? Are you having moisture or issues with your roof making it need a new roof? This is definitely the time to handle it “properly”.
Thanks for the reply! I’ve had problems with ice dams in the past and again this year (which was an especially bad year in our area (Albany, NY). I probably will have to replace some roof sheathing. The underside of the ceiling (sheetrock) has peeling paint and you can see dark spots where the rafters are. However, this problem existed prior to the dense packing. The gentleman who performed the home energy audit suggested the possibility of installing 3″ of polyiscyanurate to the underside of the ceiling for additional insulation properties which I would then cover with some kind of wooden ceiling. Should the ridge vent be closed or is that even possible? At this time I will consider any solutions you may offer. Thanks for your time and help!!
Bruce – Definitely problems! Did your auditor find signs of heat leakage from the house where the the ice damming occurred? Did you happen to notice the snow melt pattern on the roof? I have some posts with pictures of exactly this that you can check out. There’s an article on ice dams as well with a pointer to a Building Science article that goes over this in gruesome detail.
I like the idea of a few inches of polyiso on the inside and then using a nice facade inside that. I’ve recommended that before (in fact I want to do it to my house but my better half won’t let me…).
But before I did anything drastic (and potentially expensive), I would want to know why it is happening in the first place. There’s got to be some major heat leaks, maybe up through the wall and into the soffit area. If that’s the case, then even the polyiso treatment wouldn’t work.
If you can get your auditor out with their thermal camera, I would try scanning the roof from the outside on the coldest morning possible (hard this time of year) before the sun rises. That should show any hot spots on the roof which can give more clues as to the sources of the problems.
The other thing you can do, though it’s destructive, is to cut out the sheetrock in those areas where it’s damaged already and examine the roof sheathing and the construction in that area. That can be invaluable in tracking down these issues. I wouldn’t be surprised to find that the dense packing wasn’t done properly and perhaps left areas un-insulated.
Have you heard of Hunter Cool-Vent panels? They are made of polyisocyanate rigid foam with built-in venting. Foam, then 1″ cube wooden spacers about 1′ apart, attached to 3/4″ flakeboard, onto which your roofing material is attached. It was recommended for my vaulted, plank & beam ceilings, and is the cat’s meow. It replaced 1″ of old fashioned beaver board. Needless to say, I went from having icicles as big as my arm and the front door being frozen shut, to icicles only sometimes as big as my little pinkie. Big energy savings!
Thanks,I’ll have to look into those. I haven’t seen them but they sound like a great idea.
My insulation contractor Ned Reynolds of Newport, RI, is bullish on packed cellulose and says he’s be installing if for years with never a call-back. My contractor interrogated him for about an hour about vents and condensation. Ned said these days, with AC, the condensation is as likely to come in from the outside as the traditional route from the inside out and having cellulose with no vapor barrier allows the whole wall (or roof) to breathe, even without vents. The final factor in deciding was when we talked about mice. Mine is an 1850 farm house with a dry-laid stone foundation and hybrid framing (mix of post and beam and balloon frame) and it is very mousy. According to everyone we talked to, and my own experience, mice LOVE fiberglass insulation and HATE packed cellulose. Apparently the borate is an irritant to the mice and you can guarantee mice will stay out of walls/roofs that are stuffed with it. My finished attic has blown in cellulose and my cathedral ceiling-ed sunroom has 3″ of closed cell spray-in foam against the underside of the sheathing and then cellulose in the rest of the space and there’s narry a soffit vent or ridge vent in any of it. Fingers crossed it was the right decision.
I did my own cathedral ceiling this way as well. The Building Science article warns that many roofs are vapor impermeable to the top which can lead to problems. Between tar-paper, rubber membranes and whatever else is under the shingles, they note that the moisture can in fact migrate up to the underside of the roof sheathing and get trapped there. So I’m being a bit more conservative in my recommendations on dense packing cathedral ceilings. Doing what you did with 3″ closed cell spray foam would be great because the inner surface of the foam shouldn’t drop to a low enough temperature to allow condensation. So that’s safe. That construction dries to the inside. The only potential issue with that is when you have a roof leak, that saturates the roof sheathing and works its way down the topside of the foam. That would likely rot out your sheathing because it couldn’t dry out.
My preferred method for Bruce would be to pull off the rotten roof sheathing and check for any signs of moisture/rot. If there are, then you know there’s a problem. Unfortunately, my recommendation then would be to vacuum out all the cellulose and fill most of the cavity with foam to the back side of the ceiling – the part exposed when you pull the roof off. This will air/moisture seal the ceiling. I’d then leave a gap so that you could install soffit and ridge vents to allow ventilation under the roof deck which would both help any moisture in there dry out and keep the sheathing cold in the winter which will dramatically reduce the possibility of ice dams. If I were building a new house, I’d do it that way. Actually, I’d also add a couple inches of polyiso inside to reduce thermal bridging. I did the walls of my addition that way. Worked great! But I definitely take these things to the extreme…
When I have the rotten roof sheathing removed and a check reveals no moisture/rot, would you remove some of the cellulose to leave a 2″ gap for airflow and then have soffit vents installed. If the answer is to leave the cellulose as is; would you then close off the ridge vent?
Bruce – if you have rotten roof sheathing, it’s almost has to be due to interior moisture unless you had a bad roofing job and it’s been dripping for a long time.
An approach that I would consider is to create the air channel between the roof deck and the cellulose as you note. However, to avoid wind-washing the cellulose I would be inclined to use 2″ polyiso board foam pressed down into the cellulose and affixed in place with 1×2 nailers. It’s a little hard to describe.
_____________________ roof sheathing
| |I <– nailer I| | <—- rafters
| |==================| | 2" Poly-iso rigid board foam
| | ********************| | cellulose
| | ********************| |
| | ********************| |
——————————– interior sheet rock
Continued: On the other hand if rot/moisture is found then you are recommending the cellulose be removed and foam insulation be applied. Would that foam be closed as opposed to open and how many inches would you recommend?
Thanks again for your assistance!
It it were my house, that’s the approach I’d take – spray foam, closed cell.
I’d fill the cavity minus ~2″ to leave the air gap between the foam and the roof deck. Then use full soffit-ridge vent combination.
There may be some areas where you can’t get air flow due to obstructions (chimneys, etc.) With the closed cell foam filling the cavities, I wouldn’t worry about those areas. There’s not much you can do and if the foam job is done right, minimal moisture is getting through.
Let me know what you find when you start deconstruction. I’ll be very interested in seeing what happened. We can all learn from your misfortune!
Maybe take pictures and send them along. They’d be a great educational resource especially if you can trace the path of the moisture.
Love your blog. I am looking into getting mini-splits for cooling in my home in Montgomery County PA and from some reading I’ve done I’m guessing the right system might also be used to replace our 37-year old boiler and hydronic heating system for heat as well. I appreciate any thoughts you have on the efficiency of these systems for heat. I also welcome any recommendations you might have for an HVAC outfit that installs either the Fujitsu or Mitsubishi systems since they seem to be the most efficient due to the variable speed/inverter technology.
Thanks Josh. You’re close by – I’m just in New Hope.
I use my mini-splits to supplement heating/cooling year round. I wouldn’t necessarily use it as my only system however, since the output drops as it gets cold. However, you might consider just getting some electric baseboards put in as supplemental backup which you’d only use when it gets too cold for the heat pumps. Electric baseboards are dirt cheap (less than $100 each) though the electrical work will of course drive up the cost.
As for efficiency (speaking for the Fujitsu Halcyon units I use), in our climate, they are at least equal my geothermal system and they’re better than any central system for air conditioning.
A lot depends on the size and layout of your home. With all these things, you want to start with a house that is well insulated and tight. This will help keep things more comfortable and efficient regardless of your heating system, but it’s especially important for heat pumps. Also, with the mini-splits, you really need one for each area. They’re great for us because it’s just my wife and I so we have one in our master bedroom and one in the living room. But if you had several used bedrooms, I’d want one for each bedroom. That really starts adding up!
If you do stick with a boiler, I’d strongly suggest looking into the Energy Kinetics System 2000. It’s less expensive than the high end one I got but more efficient overall due to a better design.
As for installers, for the Fujitsu units, I used TCS Heaing and Air Conditioning out of Philly. The owner lives in Bucks and they do a lot of work in Bucks and Montgomery County.
For the Energy Kinetics boiler, talk to Hannabery, based out of Quakertown. I believe they also do the Mitsubishi mini-split.
How do you think the Fujitsu split units will work out in NM? We have radiant floor heat in the new house, but no cooling system at this time. I would like to keep the floor temp down a little in the winter and have some back up heat provided by a heat pump for the rooms we spend most of our time in, but don’t know if these units would work for us here due to the sometimes cold nights. Can the heat pump also be used to provide some hot water as well? I really don’t know much at all about these units, so look forward to your input.
Hope you are well,
Hi Steve, thanks for asking!
The units should work quite well for supplemental heat even down to some of those chilly SF nights. It won’t blast out the heat at 5F, but it will still be much more efficient and throw off more heat than a typical space heater. And of course, the air conditioning will be welcome in the summer.
Because of the dry air out there, you’ll have less to worry about the heat pump frosting up as well.
No luck on the hot water though. There are some interesting units that will do hot water. See: the Daiken website for more info on these. I haven’t had any experience with them unfortunately, but they do sound like good tech. Note: I just checked their website and it looks like they’re for heating only because they’re all hydronic so that’s probably no good for you.
We had 2 Fujitsu tri-zone mini-split units installed in July, and they are great! Our house is very comfortable now, and our first utility bill was a very pleasant surprise. Thanks for the good advice!
Your brother Stephen in Santa Fe
Hey, that’s great news! That’s a great system with all those independent zones. Glad it’s working out for you.
Hi Ted, You’ve written extensievly about heat pumps and particularly the Fujitsu. I happen to have the AOU24RML1+ARU12RML x2-Concealed Ceiling Heat Pump Dual-Zone Mini Split.
I mounted the units behind a wall and did a small dust into the room which hides them nicely. I love the performance, we mounted them upstair sin a loft room and they basically keep 3200 sq feet cool most of the time. My question is whether or not you can have them shut off like traditional HVAC units? Once I turn them on they run constantly and of course the inverter unit varies its speed greatly. I’d just like the to shut down at night sometime and can’t figure out if you can set them to do that. Thanks jim
Hmm, I’m not familiar with the specifics of those units but my units (12RLS) behave the same way. The blowers one them are very efficient and when I run on “auto” mode, they slow down to a whisper.
I do notice that the outdoor units do shut down even when the blowers are running and when I monitor their power draw, it drops down very low.
Otherwise, when I want it “off” I actually have to use the remote and turn the unit fully off.
sorry for the typo’s on the previous post. That’s supposed be “a small duct” and “upstairs in a loft…”
That’s been my experience also although the blowers seem to have the same consistent output. The outdoor unit slows WAY down! These are the same units as yours except meant be roof or ceiling mounts. We adapted them for our particular utilization. I’ll check and see if the blowers are on auto mode and if they slow as well but overall these things work like a champ! I think they even use less or equivalent energy of an attic fan. Thanks again JIm
Interesting. My indoor unit has a number of setting – auto, low, medium, high, quiet. I usually run it on medium or high during the afternoon then switch it to auto for other times when demands are lower. At those times, the fan varies considerably on ours. Maybe the ceiling version behaves a bit differently?
Hope you’re enjoying your holiday weekend and you don’t answer this until Tuesday. Back to these minisplits again! I’m wondering about two things. The unit is locked when I try to set the thermostat at the remote as opposed to the unit. I’m concerned because the units sit in an attic space where it is hot so I’m not sure where the temperature is actually measured. I’d rather have it at the remote so I’m wondering if I can unlock this factory setting. I’m also having trouble getting the controllers to allow me to set the set back time and temperature. I also can’t get it to set in timer mode. In both functions I can get to the setting program but once I select a day, single day or all nothing else sets like time or temp. i keep going back to the instructions to see if I’m missing anything but no luck. Any ideas? thanks, jim
I’m always on my email. Don’t feel bad because I don’t have to put too much thought into this answer – “I don’t know!”
Seriously, I have no idea how that works. The only recommendation I have is to call the installer and see if they can help. Sorry I can’t be more helpful than that.
When you find an answer, let me know. I’m sure others will be interested in what you learn.
We got a quote for minisplits and then, in light of the age of our boiler and the price of oil as well as the tax credit that runs until 2016, we’re considering upgrading our hydronic system to geothermal heat pump instead of getting the minisplits and then later replacing our old boiler. Do you have any thoughts about this and/or a favorite brand?
The geothermal incentives are indeed attractive. The trick is, they’re not very friendly with conventional hydronic systems, unless you just have radiant underfloor heating.
Here’s the problem – I should probably write an article about this because it’s a common question…
Conventional boilers run at very high temperatures. By default, most are set up to run at 180F. When you run water that hot through radiators and baseboard fin-tube convectors, they throw off a lot of heat!
Geothermals are very efficient at making hot water at temperatures up to about 120-130F. Some can push this a little, but in general, physics stands in the way, so you’re very unlikely to get a geothermal thats producing hot water much above 130F with any reasonable efficiency.
So you have two things working against you. First, if you try to generate water hot enough for the radiators or baseboard convectors, you lose the efficiency. Second, if you run at a lower temperature where the geothermal is still somewhat efficient, the radiators won’t throw off enough heat to keep you warm.
If you have proper underfloor radiant (by proper, I mean tubes embedded in concrete and a tile floor), you can run at much lower temperatures, like 90F. At that temperature, geothermal is very efficient. So if you have that type of radiant of this sort, you can get very good results.
Feel free to ask if you have more questions!
I should have been more clear- we’re running ductwork anyways, b/c getting enough cooling to all the rooms we need in our upstairs (6- 2 of which are rooms off of rooms off of the hallway) would require it anyways to work with our architecture and the minisplits. And we are also tired of the ups/downs of the oil market and trying to budget around that. If our boiler were newer, we would probably just do the minisplit upgrade for cooling but since it’s such a dinosaur (38 years old) we’re gonna scrap it.
Long term plan is to rip out the hydronic system as we renovate each room over the years.
Back to the geothermal: do you have a favorite brand and/or setup?
Ah sorry. Well it was a useful discussion anyway!
For that, usually it turns out that your best luck is with the best installer in the area. Get someone really experienced who has done dozens or hundreds of installs and talk to references. Every Joe is jumping in the business because of the incentives so there are a lot of hacks out there.
Internally, most of the systems are very similar, so I wouldn’t worry about brand A vs. Brand B.
We have an expanded log cabin in Northern New Jersey with too many addition mistakes to mention, but we have an urgent one right now that I’d appreciate any input on:
We had our vaulted/cathedral tongue and groove original (about 60 years old) pine ceiling (which used to be “A” frame but we made a loft above, so now only half an A frame) re-roofed about 4 years ago. Unfortunately was not advised on insulation, (we had no GC for this addition, just a “project mgr” who wasn’t very knowledgeable in construction, as it turns out. Anyway, we know we are losing some heat out of there and now we have a leak but can’t pin point it. We were thinking of insulating on the inside with foam then sheetrock. We haven’t done anything because we didn’t know what to do about moisture issues, vapor barrier, etc., and it’s a good thing we didn’t because now we have a leak! We also have two skylights fit within log beams in that area that we put in 10 years ago. So, we don’t know how to go about re-roofing this area as far as insulation and correct roof system for this type of vaulted wood ceiling with skylights. We are getting ice cicles in that roof area but not sure if due to heat factor or need wider gutter due to pitch, etc. We believe the last roofer put a layer of ice shield, but who knows.
On another note, we have to replace our gas water heater soon which is in a low ceiling basement. Current water heater is 50 gallon and it really doesn’t have enough ventilation area due to low clearance, so we’ve been told. We have 2 CO readers and haven’t had a problem in 10 years here. We run out of water if two people take a shower at same time. Seems by looking online, that the lower profile tanks only come in electric or are only up to 40 gallons and since we are already running out of hot water at 50 gal, I’d hate to go to 40!. So we don’t know whether to try a tankless or what. Also we have hot water lobster in upstairs bathroom because takes for ever to get water warm up there (probably bad insulation below!) The lobster definitely helps but isn’t really compatible with tankless.
Any recommendations there?? I could go on and on, but will stop with those two pressing issues!
Hi Mia, Thanks for visiting. Sounds like some real issues going on there!
Leaks can be tricky to find because sometimes water will behave “strangely.” However, most of the time, it’s fairly predictable when there’s a large enough quantity that gravity is the main force on it. In general, it will run down hill, with a little side-to-side movement if it hits a barrier that redirects it. The tongue and groove ceiling, I’m assuming runs parallel with the roof’s width – i.e. not from ridge to soffit but from side-to-side. What can happen is that the water can run in the grooves and go sideways a bit. But, for the most, your water will leak into your house pretty much downhill from where the water leaks into the roof.
So the first question is – is the leak downhill from the skylights, maybe off to the side by a foot or two, but still pretty much downhill from the skylight?
If not, might the leak be somewhere downhill from a chimney?
Unless you have really bad shingles, the probability is vastly higher that the leak is occurring at the flashing for the skylight or chimney. With either of those, it should be relatively easy to fix for someone who knows what they’re doing.
So that should get you started troubleshooting the roof leak. You can also verify this problem using the high-tech testing called “the hose test.” Seriously, if you methodically spray the hose at your roof, you can pretty well pin down where the leak is. There’s definitely a technique to it, because it can take a real soaking and 5-10 minutes for the water to soak in and drip down to where it’s coming into the house. But the first thing I would do is a detailed visual inspection in the vicinity of the leak and up the slope, all the way to the peak.
Regarding your water heater – that lobster sounds interesting. I’ve never heard of it. But looking at the description, it’s probably doing the opposite of what they say. It’s not saving you energy because it’s constantly re-heating the water in the pipes every time they cool down. This is great for supplying instant hot water, but it’s bad for efficiency. The “chilli pepper” is a much better idea. You push a button and it circulates water in your pipes until it gets warm. So you still have to wait, but at least you’re not flushing tons of water down the drain. It’s the best compromise between a circulator and nothing.
With something like the Chili Pepper, you could use a tankless. Given your situation, that’s the route I’d go. You’ll just have to get a big capacity tankless system if you want to take two showers at once. Or, maybe consider using a lower flow shower head. You might have read my article on these…
Hope that helps. Post again with your leak troubleshooting findings.
Thanks Ted, we’ll try those suggestions. Any suggestions for insulating materials for that problem area roof to prevent heat loss, assuming we are up to re-roofing? We did have someone come in with an IR camera a while back that said we were losing heat through the ceiling, but don’t know if it’s enough loss to warrant investing in ripping off shingles and insulating $$!
It’s difficult to comment on insulation without knowing the ceiling construction. You noted that it’s tongue and groove. Is there anything above that or are the boards just nailed to the rafters? That would be the typical (incorrect) construction method. If you’re lucky, then they attached sheet rock to the rafters first, which acts as a good air barrier. So my answer will vary considerably depending upon that.
The big problem is, if they just attached the tongue & groove ceiling to the rafters, you can’t really properly insulate above it without ripping off the roof sheathing as well as shingles, and you really don’t want to go through that unless absolutely necessary!
If you don’t have moisture problems (other than the existing leak) then I wouldn’t mess with the roof insulation. But if there are signs that the roof sheathing has been moisture damaged and they are going to rip off the roof, then you have a once-in-a-lifetime opportunity to redo the roof “correctly.”
In the case that all the roof is going to be replaced, the best solution is to coordinate a spray foam insulator to come in right after the roofers rip off the sheathing. They can then spray the foam right in to the back side of the tongue and groove ceiling material. This will air and moisture seal it better than anything else. To keep costs down, you could do an inch of closed-cell foam and then have the rest of the space filled with damp applied cellulose, leaving 1″ of air space between the top of the cellulose and the roof sheathing. This is a ventilation channel allowing air to rise up through the soffit, go up the channels and out the ridge vent.
If you go this route, check out the excellent Cor-a-vent product for soffit and ridge venting. It’s the best I’ve seen (used it on my own house).
ok, thanks again!
How noisy are the Fujitsu heat pumps? Are they like a hotel unit?
Bob – they’re much better than most hotel units which I find to be very noisy. However, if you turn them on “high”, they’re moving a lot of air, so they definitely make a fair amount of fan noise. If you run it on any of the lower speeds (quiet, low, medium), they are very quiet indeed.
hi Ted – i’ve read your comments regarding the Energy Kinetics system 2000 and i’m wondering if you might offer me some advice – i live in northern NJ in a 2700′ sq house that i bought in 2007 – the house has EK 2000 system with water tank (previous owner installed). I want to convert the house to natural gas from oil and have been told that i can convert the burner to a gas burner (without replacing the EK 2000 system which has been good to me)- i’ve also read that EK 2000 is really meant “for oil” – but in my situation since i already have the system in my house i want to avoid scrapping it and buying an entire new gas boiler. How easy is the conversion and how do i find a compnay with experience doing it ? all the EK 2000 dealers seem to be oil companies around NJ. How long is the job to convert and what would you estimate the cost for conversion parts? If you were in my situation would use also go for the conversion vs. an entire new system? is it ‘really true’ that the EK 2000 works just as well with NG compared to oil ? thanks in advance for you help !
First, I’ll give you a disclaimer – I’m not an HVAC tech/installer, so I can’t give you any real-life numbers or comments based on experience with this type of conversion.
As I understand it, you should just be able to replace the burner with a natural gas burner that has been designed for oil to gas conversions. These type of conversion products, which should cost a few hundred dollars, should work fine because their designed for the purpose, and the flame they produce should be cleaner and less corrosive than an oil flame (which can produce sulfuric acid). So in theory, you shouldn’t have any problems.
Here’s a link to one such device: http://www.waynecombustion.com/news.aspx/oil-to-gas-conversion-burners
I suggest you call EK since they’re based in NJ. They should be able to give you a lead on someone in your area to do the conversion. However, if they don’t know, any competent gas HVAC tech should be able to swap out burners for you since they design these things to be “plug and play”
As for your other questions – I would absolutely go this route if I had NG in my area. The EK2000 is a fine unit, so I’d keep using it as long as possible.
Good luck! Let me know how it works out for you.
thanks for your quick reply and advice !
I am the author of the McGraw-Hill textbook “Retrofitting for Energy Conservation.” I have a free energy audit spreadsheet on my website at http://whclark.com as well as excerpts from the book. The book is now out of print, but McGraw-Hill has now transferred the copyright back to me. You can now order the book in a handy spiral bound form for a fraction of the original cost.
Thanks for the contribution! I’ll check it out and hope it proves to be a valuable resource for my readers.
Hi Ted, I just found your blog and I’m really impressed with all the information. We are building a 2700 s/f house in Massachusetts and are now in the process of getting quotes from insulation contractors. We were planning to go with the “flash and batt” method with an inch of spray foam topped by fiberglass batts. So far, one estimator has said that’s “a fine method” and another says it’s not recommended in the northeast because over time, temperature fluctuations could lead to cracks in the relatively small thickness of foam. What do you think? We are using 2 x 6 construction.
Thanks for writing. Hope I can be of help. My folks live in MA (in Falmouth/Woods Hole) and I spent quite a few years there myself. Beautiful area of the world…
On to your question – Flash & Batt: Even worse than cracks, if done improperly, it can lead to severe moisture/mold/rot issues. Here’s why – typically it’s done by spraying that thin layer of foam on the outer wall sheathing from the inside of the house, then packing the rest with inexpensive insulation. The best analogy I can make is imagine wearing a sweater with a rubber raincoat over it.
To continue the analogy, when you sweat, what happens? That moisture goes right through the sweater then comes to the rubber barrier. Before you know it, you’re dripping wet! This exact same thing happens with flash and batt. The fiberglass allows the moisture to flow through and the foam traps it.
Having said that, you can do flash and batt correctly in cold climates like MA. If the foam is sprayed to the back of the sheetrock and the fiberglass is packed outside the foam. Then what happens is the moisture from inside the house stops at the foam and never gets into the cold cavity of the walls or ceilings. Here the sweater and rain slicker analogy doesn’t work because the physics are different.
However, almost nobody does flash and batt like this because it means you have to install the sheetrock before the outer walls and roof sheathing.
Another way you can do F&B correctly is to use thicker foam on the outer walls. In your climate, you typically need at a minimum of 2″ (and likely more) foam if you’re going to use fiberglass with the foam. I’d have to go into the physics of dew points and moisture to fully explain this, but it’s well documented. The research of the best building scientists in North America supports this.
If I were you, rather than using 1″ of foam and the rest fiberglass, I’d go with 3+” of foam and forget the fiberglass. High density spray foam gives you R6.5 to R7 per inch, so with around 3″, you hit the requirements for building code and you don’t have to worry about condensation, mold and moisture like you would with F&B. And of course, the thicker foam the better, but you’re trying to get the best bang for your buck, so there’s going to be an optimal thickness for you based on what is cost effective vs. the R-value.
I’m building a log home and want to plan a good roof. I would love exposed rafters on a cathedral ceiling, so a “built up” roof seems the way to go. How would you go about doing this if spray foam is too costly? Here’s my thought: rafters on a ridge pole, then I want to do plywood ceilings, so I would put 3/4″ plywood on the rafters. I would then spray foam fill everywhere plywood sheets meet. Then I would toenail 2×12′s ontop of the plywood. Use visqueen in all of the gaps I’ve created with the 2×12′s. Then fill the cavity with cellulose, but leave 1.5 inches for venting. build soffets on the overhang and install a ridge vent. This is in a high country arid climate, but it does rain and snow. Thanks!
Sounds like you’ve been doing your homework!
I’m not visualizing your proposed solution very well.
How about using one of the sheet-foam products like polyiso or blue-board? Use that for a couple layers, staggering the seams 50% between layers and taping seams. That can work really well to prevent air movement. Then you could use the cellulose for the rest of the cavity, with the air gap, giving you reasonably priced, high-R-value structure.
If you haven’t read through the roof material on the Building Science website, take a look there.They’ve got designs for a variety of climate zones and construction techniques.
Sounds logical to me! Thanks, Ted!
Ted, I’ve got serious condensation in my attic despite a humidistat/thermostat-controlled exhaust fan and gable vents. The cause might be air leakage through 15 hi-hats and other sources. I’m looking for knowledgeable contractors who can deal with this problem and would appreciate your suggestions.
Thanks very much.
You probably nailed it – those 15 high-hats are like open windows as far as moisture is concerned. If you’ve got insulation near them, and it appears discolored, then air has been moving through them.
There’s a good chance that it’s going through any access hatch/pull-down ladder as well.
I see you’re in the area – what town are you in? I might have a couple people who I could refer you to. You can email me directly: ted at soleburymountain . com
Ted…. I’d appreciate any leads you can provide to deal with the air leakage, ventilation (if necessary) and possibly insulation. I live in Malvern. Thank you!
I recently had a pair of Daikin Quaternity mini split heat pumps installed. A 9k for the master bedroom and a 15k for open area entry/living/dinning/kitchen.
Extremely happy with my choice but wondering if a behaviour issue is common to all mini splits. I read your review on your Fujitsu RLS. Do yours or any of your followers have this same issue:
Both heating and cooling will move approx 5 degrees F passed the set point. e.g. I set my units to 65F to maintain a room temp of 70F as measured on my aux heating tstat and another I have for a propane f/p. At the same time the display on the Daikin remotes indicates that the sensor on the wall mounted (8 ft ceiling) indicates 72F. Both units behave the same.
I can understand the extra 2 degrees on the sensor, based on heighth but is the 5 degrees passed set point not a tad excessive?
Those look like excellent units. Actually, they look almost identical to the Fujitsu, so I wonder if they’re the same unit with different covers?
As for your set point issues – I do adjust mine based more on the stat near where I sit rather than the number on the unit. But in part, that’s because the units are mounted in somewhat strange locations, so that will confuse the issue.
For example, I had to mount my living room unit near the floor instead of high on the wall. So the unit is measuring the floor temperature rather than the ceiling temperature. With typical stratification of air, you might have a five degree temperature difference between these locations. Is seems like you’ve already thought of this. Five degrees does seem excessive.
In my experience, the temperatures are pretty accurate overall. In my bedroom, where the unit is mounted on the wall, the temperature setting and the wall thermostat match up within a degree or two.
So the quick answer is, 5 degrees seems excessive, assuming that you’re getting good air mixing in the room. Is this a problem? Not really, it’s just an arbitrary number. As long as the units keep the temperature consistent, I wouldn’t worry about what it thinks the temperature is.
you’re right about the similarities between RLS and Quaternity. RLS was my 2nd choice, I went with Daikin based on the Dehumidification capabilities. Being able to lower humidity without lowering temperature seemed a nice option for our region in Nova Scotia.
My installer tells me Daikin can change boards in my units to overcome the 5 degree diff.
He’s going ahead with that for another client and will get back to me based on those results.
thanks again, great blog.
Thanks for the info. Great to hear about the board. Hopefully that will get it all going just right for you.
BTW – the Fujitsu also has the dehudification mode. I use that in spring and fall.
Thanks for the feedback. Hope to hear more from you.
Great Blog. Love it. i got the Daikin mini split ductless heatpump last week. I had many quotes for all names in the heatpump world. i chose Daikin and am satisfied. Like the above post. I too am getting a difference of temperature in one room. The electric baseboard heater themastat is reading almost 4 degrees in the difference. The remote is set at 18c and the room reads sometimes 23c on the wall mounted themastst and a handheld themastat
Also it seems the fan never stops running. (not sure how efficent this is) Even if the remote is at 16c and the room is reading 21 the fan still comes on and blows. weird..?
The manual for the Daikin lacks comsumer friendlniess.the book is pretty bleak and provides no senerios or options to maintain the system.
Im not sold that the machine running 24/7 is the best way to acheive maxium efficency
Overall im happy with the install and the product, just wish i knew a lot more about where to set the system and how to acheive the best numbers…
Halifax Nova Scotia canada
I agree, the manuals on most of these systems leave you guessing. They tell you what the buttons do and that’s about it.
I think the temperature issue is likely due to how they measure the temperature. Since they monitor the temperature of the air stream passing through the unit, there’s going to be variation dependent on the installation location. For example, in one of my rooms, I had to mount it low on the wall under some windows, so it’s picking up the cooler air that pools near the floor. In another, it’s more optimally mounted, high up on the wall, so it’s measuring the air temperature more near head height.
Most of these units have optional wired thermostats so that you can control them at a more appropriate location. I didn’t bother because I just naturally adjust them to the desired comfort level of the room rather than shooting for a given temperature. It’s not perfect, but it saves a few hundred dollars for the remote thermostat kit!
On the fan always going – this allows a much more even air circulation and hence temperature distribution. The blowers in these units are super efficient, so you’re not using much electricity with them running all the time and the comfort benefits are worth it.
what outside temperature does not work on a 12,000 btu a/c heat pump. we live in montreal, qc.
You’ll have to check with the manufacturer’s spec sheet on your unit. Every unit has an ‘output curve’ that defines how much heat it can deliver based on outside conditions. For example, there are some modern units that are designed for cold temperatures and can put out a good amount of heat even at 0F. On the other hand, some normal system drop down to about 50% output when you get to freezing temperatures.
Typically, when you’re about five to ten degrees below freezing to about five degrees above freezing, heat pumps struggle because of the need for defrost cycles. If you look at the outdoor unit at these temperatures, you’ll see a lot of ice forming on the coils. The unit has to run in reverse periodically to melt the ice. When it does, it actually puts cold air into the house and heats outside.
However, the overall efficiency of a heat pump, even at these conditions, will be higher than using a normal electric space heater. So even when it’s somewhat cold out, you’re best off using the heat pump and supplementing it with other heat as needed.
Check with the manufacturer to see what range of temperatures they recommend.
Hello Ted, you have answered a couple of my questions about the 12RLS and this week I had one installed. The first couple of days the temp was about 0 F but last nite it went down to about 10 F and has not warmed up much today and the Fujitsu is performaning well, I have an older home on three levels with variable degrees of insulation, all new windows. The unit is on the lowest level of three and is just outside my kitchen window and the indoor air handler is just a few feet away (6′) over the kitchen sink. Its keeping the house nice and warm but I am wondering what can I expect as the weather gets colder? I just noticed a little while ago that it went into defrost cycle for less than 10 min. and when it restarted the fan came on a what seemed a higher output than normal when set at”medium” I chkd the output air at the unit and it was about 94F with the remote set at 74F. Is that normal in you experience? I was disappointed with the manual that came with the unit. very little about how to operate it for peak performance, and nothing on what to expect with varing climate conditions.
Thanks for your help Ted
Thanks so much for writing. Glad to hear that the Fujitsu is working well under such harsh conditions! I haven’t pushed my units that hard, so it’s great to hear from you.
The defrost cycles get “funky” – expect some strange sounds and fan operation during that time. I’ve found that my unit suddenly goes to defrost, the fan cuts out and then it works overtime when the cycle is done. So the behavior of your unit sounds “normal” from my experience.
The output air depends on a lot of factors, but typically, I get 100-110 degree air out during moderate temperatures outside. When it gets colder, the system has to work harder, so 94F sounds in the right ballpark.
My expectations these days for manuals are pretty low. I would have liked to see more also. Pretty much, I just set the units to “auto” and put the temperature around where I want it to be, and let it do it’s thing. You’ll definitely notice diminished output as it gets colder. With heat pumps, 50% decrease in overall heat output when the air drops to 10F is not unusual. These mini-splits with inverter drive compressors do better because they can push the compressor hard at cold temperatures but you’re still fighting physics. If you get appreciable hot air out when it’s under 10F, consider yourself lucky
I hope you’ll report back and share your experiences as the temperatures drop.
Hello Ted, well since I last wrote to you just after having the 12RLS installed (Dec 14) we have had a wide range to temps here. All the way from -15C to +5C, sorry I’m going to give temps in celius that is what I’m used to and all my themomters are in C and thats how I’m recording temps. Anywat during this great variation in temps I have seen output temps in the 35C to 41C depending on the outside temps I guess? For instance on 18 Dec the outside air was -15C and the units output was 37C, on 21 Dec with an outside temp of -3C the output was 41C.
I keep the remote @ 74F and set on AUTO.
What I am most pleased about is that it is keeping the rooms I wanted to heat with the 12RLS at about 74F pretty constantly. Today for instance its really brutal ot there the temp is 12C and heading lower but the wind chill is already -22C and that is cold for 3 in the afternoon.
thats it for now
best regards and happy new year
Hi Jack, that is an excellent New Year’s message. I’m really happy to hear that these are working out for you so well. I’ll bet Fujitsu would be as well.
You’ve got it right – the maximum output temperature of the system will be directly related to the temperature. I’ll tell you, 37C output from a heat pump when the outdoor temperature was -15C is spectacular. From what I’ve seen in conventional heat pumps, you’re usually lucky to get 30C at those outdoor temperatures.
Thanks so much for the report. I’m sure others will be very interested in this.
I can’t find a Fujitsu dealer in Northern Ohio. Did you have a local Fujitsu dealer or did you have to get them some other way? Thanks.
I had a local HVAC contractor supply them.
There should be someone in your area qualified to install them.
Try calling Fujitsu and asking for an installer near you.
Hello Ted, another report from the “frozen” north. If you think you have enough info on my experience with the 12RLS let me know, I don’t want to get boring. I will try to give temps in both celcius and farenheit so as not to confuse anyone reading this. Canada changed to C back in the mid eighties and I have mostly mentally converted. The remote for the 12RLS is just in F as near as I can find out.
The morning of the 29th Dec here was quite cold -23.5C (10 below 0 F) but was clear with a calm wind. At 7:30 AM I ck’d the output of the 12RLS which was at 35C ( about 97F).
I usually keep the 12RLS set at 74F which seems to keep the area I want to heat at about 24C (about 74F) which seems to be comfortable most of the time.
At about 8:30 AM with the outside temp still at about -23C I upped the temp control on the 12RLS remote to 76F, within a few minutes the unit was putting air out at 39C (about 102F?) with a greatly increased fan speed.
The temp that day stayed around -18 to -19C (3 or 4 below 0F) and the output from the air handler maintained at about 35C with the remote set back to 74F.
My observation so far is that the heat pump does better on clear, dry days rather than on a day like today which is cloudy with snow flurries and high humidity.
Today while the temp is only -12 or 13C the heat output is still at about 35C.
Well Ted I hope you and your readers fine this info useful?
Jack, it’s always good to hear from you. I’m a data junkie so I never get tired of this. Plus, there’s nothing more valuable than actual field experience to help others who might be considering a similar setup.
The more you say about your experiences the more impressed I get. I’m alway very conservative recommending heat pump technology in cold climates like yours, but it really seems like the Fujitsu is working well.
Your observation about the type of weather matches up well with the theory and my own experiences. In more humid weather, the heat pump coils will freeze up more, requiring additional defrost cycles and lower overall heating effectiveness. With dry air, the system can crank away without the performance degradation.
Thanks for the info Jack, I am really surprised to see the 12RLS performing that good in frigid Canadian conditions. It gives me confidence that a mini split heat pump would perform well here where the temperature rarely gets below 0F(-18C). I am in the process of looking for someone that will sell me a Fujitsu 12RLS. I would like to avoid some of the high installation costs and equipment markups by doing part of the instillation myself and letting the contractor make the line set connections, do the pressure test, and vacuum the system.
Due to Fujitsu’s strict “dealer sales only” policy it might not be possible for me to install any part of the system or even find an HVAC contractor the sells Fujitsu products in my area. Hopefully other manufacturers’ heat pumps will perform as well as the Fujitsu 12RLS, although the 12RLS has the best SEER (25) and best HSPF (12) of any mini-split I have looked into.
Check into the Daikin units as well. Check out this link. Maybe you could find someone to install one of those.
There are some sources on the web where you can buy the 12RLS for under $2000 and if you’ve got a cooperative HVAC contractor, you could do much of the work yourself. But as you noted, you’d be unlikely to get a warranty.
Mitsubishi has an extensive line of mini-splits though the performance specs aren’t as impressive. But they’re considered the workhorses in the industry. For heating, be sure to focus on the HSPF rating rather than the SEER. Though they typically go together, the HSPF’s may not vary as much as might be indicated by the SEER’s.
There are also some units that have a “turbo” mode for when it gets cold. You lose some efficiency, but that’s less important than heating capacity when you’re just trying to stay warm.
Ted: we bought a home that has 3″ rigid foam (owens pink) that was cut between old timbers and foamed tight to the exterior wall. The builders then built and insulated a 2×4 wall inside the old wall to provide a flat wall and add insulation value. This wall was insulated using r-15 Roxsul brand insulation, and a 6 mil vapor barrier before sheetrocking. When we cut into the wall to add an outlet for TV, there was moisture on the inside of the poly where it contacts the Roxsul- not much, and only on the south side. I asked the builder who did the work, and he said he didnt want the vb but code said it had to be there. They had to keep the historic exterior, so they couldn’t add rigid board to the outside. The building inspector indicated that he required the vapor barrier per code against the builders wishes…. now what do we do? What is right? Dubuque IA
When you say inside, do you mean facing the sheetrock or right against the roxul?
That sounds like a pretty tough situation. The rigid foam is slightly vapor permeable but clearly not compared to the vapor barrier! Most building science folks push for removing of those building codes that force the blind use of vapor barriers exactly for these reasons.
The strange thing is that the moisture is condensing near the inner wall. That’s a big concern because that’s a red flag for a LOT of moisture being trapped in the walls.
I’m assuming this was during the winter?
On the south side is also suspicious. Sometimes this happens when the sun “pushes” the moisture through the wall, especially with brick exteriors which can act like sponges for moisture. What is the exterior of this wall like?
The more information you can provide, the better.
So far, we have only found it on the roxsul side of the plastic, only on south side. The exterior is only limestone and concrete foundation, clapboard siding on bottom of framed walls, gingerbread above windows/gables. Exterior also has a double layer of aspalt felt, thicker than current 30lb. We found this putting in exterior outlets. Did a larger inspection hole inside, roxsul and pink are dry- less than 7-12% once past the outer boundry using moisture meter- so the moisture is definately at the poly and roxsul. Did 3/8″ drill holes in wall along the top of the stud cavities, where they would be covered by new crown, and some have moisture marks 2 days later. Builder did this wall when high humidity in summer, and no AC. AC was used after drywall was sanded before painting and floors- his thought is moisture is trapped in cavity from this summer period, and has migrated to the interior face. NEW inspector agrees with builder- no vapor barrier, only housewrap on interior if desired. Rafters and plate area are foamed with close cell up top; the house has 6″ polyiso board on top of old roof deck, and iso board cut between full 3×6 rafters. We did some test readings there and up on roof via ridge and other points- all were less than 10% moisture. So at least it’s limited to south wall!
My only thought now to solve is to drill holes at base and behind crown area to let wall breathe, otherwise we have a project in taking down drywall and removing the interior vapor barrier. Or put a whole lot of holes in wall with drill, then mud and repaint! Hope you might have some other points to ponder on this…
You question/situation is so interesting, I’m going to turn it into a full post. Stay tuned for the full report!
Ok – another article done!
Let’s continue the dialog in the comments of the new article.
I wanted to follow up with you to see if you saw my article addressing your moisture issues. I’d be very interested to learn what you discover as you do work on your walls. This could be a great learning experience for others and help them avoid similar issues in their own homes.
Here’s the end result: we pulled the drywall off, and the poly. Out came the roxsul just to chek for any other issues, such as leaks, etc. Nothing was found, and the roof is brand new, no water issues were seen on the foam or foam side of the wall, or near the roof plate. The moisture meter reading was less than 7% overall on the old timbers where they were probed. One interesting thing to note from the builder- the home was pressure washed by the lead abatement crew to remove any dust and residue from lead items (Dubuque area commonly used lead mine leftovers for mixing plaster, cement, etc.). Again, this was in the summer, and the builder began right after the crew left. We only found the moisture on poly right at the roxsul; nothing in the roxsul or past towards the foam. In fact, even with no wall/insulation/vapor barrier, the wall is warm to touch from the sun hitting the exterior (historic gunmetal grey paint- explains the heat that is absorbed)
We are letting the wall breathe out now, and next week we are reinstalling the roxsul and drywall, and NO vapor barrier. All the moisture seemed to be on the poly, where it couldn’t escape as it was sealed tight. As a note, no other walls in the old part of the house had this same issue. However,the other walls are getting holes drilled in the drywall and through the poly, just make sure they can breathe as well.
As the previous inspector order the wrong things to be done despite the objections of the builder, we are asking for a refund of a portion of the permit fee, which is about the most we can do in this case. Like you stated, drywall and paint are inexpensive! (plus, we can add the outlets we wanted, which is what led us to discover the issue in the first place! Bonus!) As a note the energy efficiency of the home- our furnace rarely runs- the wood stove heats the home, and the house is so well insulated that even with no fire going, it took over 36 hours for the interior temp to drop from 73 to 65 with outside temps of 20 to 40f. Someone forgot to turn the furnace on when we left for Christmas!
Thanks for the report. Very interesting and still perplexing! Please share if you learn anything else in the future.
Ted, here is something I wrote up about all the work I had done in 2006. It has a link to the Cool Vent panels.
After comparing the energy audit results and recommendations of three different contractors in 2006, I chose one of the companies to complete the majority of work that needed to be done to make my home more energy efficient. (Other contractors completed smaller jobs.) The main contractor initiated the paperwork necessary for me to receive not only a $6,000 Energy Star grant, but also a 4% low interest loan through NYSERDA. Here is a list of the work done:
1. Replaced original 1950’s era gas furnace with new high efficiency model
2. Replaced a nearly 20-year-old refrigerator with an Energy Star model
3. Replaced a 1970’s era (avocado anyone?) washer with Energy Star model
4. Replaced 4 ten+ year old low-quality vinyl windows with Energy Star windows (remainder of windows already replaced with triple-pane vinyl windows)
5. Replaced 6 single pane basement windows with glass block windows
6. Added AirKrete ® http://www.airkrete.com/ insulation in all exterior walls
7. Added foam insulation to all rim joists, and under house wing over garage
8. Replaced rear and side exterior doors (front door already replaced)
9. Finished installation of Hunter Cool-Vent TM panels on roof over vaulted ceilings http://www.hpanels.com/pages/cool-vent_articles.html
I now have a year’s worth of data on the resulting energy savings, from my local utility’s website showing my home’s energy use over the past two years. My gas usage in therms decreased by 25%. My electricity use in kWh decreased by 44%. Not too shabby, and I still have things to tweak!
My electric use over the past year (12/07-11/08) has been 3,383 KWH, which is 44% less than before all the work was done. 3,383 KWH times .095 rate for renewable/green electricity = $321.38 + RG&E delivery charges (varies). My gas use of the past year was 522 therms. That is 25% less than it was before the improvements. 522 therms times $1.305 per therm = $681.21 + RG&E delivery charges (varies). All totaled, my utility bills over the last year were about $1480.00. [This would be a lot easier to figure out without RG&E's separate delivery charges!]
Margie, thanks so much for sharing. Kudos on a successful energy-efficiency renovation!Your savings are impressive. It’s really meaningful to share ‘real-life’ information like this. I think a lot of people are skeptical and think that all these things are theoretical. Keep up the great work and keep spreading your successes.
By the way, it looks like they changed the link to the panels. Here’s a link to the page of products.
You’re welcome! It is a personal mission of mine to encourage and teach about saving energy. Thanks for correcting the link.
The level of insulation in justice’s home is truly impressive! I can’t get any more in my walls – would have to reside the whole house and put foam panels on the outside. If my house could be jealous, it would be!
First off, you have a great page not just in information, but in overall design. I have a question for you and haven’t been able to find a good answer yet. I live in a Upstate New York home built in the 30′s. The previous owner decided to add an attic bedroom, but they didn’t insulate correctly.
The attic has your basic knee walls, improperly insulated with exposed pink fiberglass on the unfinished side. That is going to be easy to fix. I cut away some of the floor on the finished side to see what was under it. They left kraft faced R-22 spanning the joists between floors (2x8s). It was clean so I’m guessing air movement is minimal. Would it be beneficial for me to remove some of the floor and properly block below the knee walls?
My goal is to make the room more comfortable and energy efficient. I would like to get a return on my investment, but may not live here much longer than another 5 years. Does the work sound worth while?
Thanks Chris, I appreciate the feedback!
Those attic rooms – ugh, everybody seems to do them wrong.
If you can get behind the kneewall to see the insulation, work from that side. Usually the cavities are open and easily accessible for air sealing. The quickest/easiest way is the “insulation pillow” – fill a kitchen sized garbage back with insulation and then pack that in the gap under the kneewall to form an air-tight plug.
On the back of the wall, I know some contractors who will use 2″ rigid board foam affixed to the knee wall studs. That insulates the studs to minimize the thermal bridging and holds in the fiberglass that’s in there so you double the benefit giving a knee wall R-value of about R-20. An alternative is to insulate below the rafters and not on the back of the kneewall. Depending on access, this may or may not work for you. See the link at the end of my reply for a diagram.
Doing these two should be a cost-effective weekend job if it’s a modest sized space.
If you can, you should also take a look up the sloped ceiling (from the attic side) and see what’s going on in there. Most homes of this vintage will either have this space packed with insulation or have nothing at all. If it already has insulation, and the roof shows no sign of moisture damage, don’t touch it. I don’t like messing with things that have been working for decades. If it doesn’t have insulation, this can be a tough retrofit. Without insulation, those sloped portions will bake in the summer and freeze in the winter. There’s some serious thought that has to go into that retrofit because done incorrectly, you can end up with a rotten roof.
I’d suggest taking a look at the following link for some ideas:
Thanks for the input. There is enough space behind the wall for me to crawl and repair. I actually did what you suggested with the rigid foam over the studs (in a small test area) a few months ago. There is a lot of conflicting information on the internet, and some of it indicated that I was just going to create a moisture problem between the XPS board and the faced insulation that is currently in the knee wall. So I stopped and decided to research more.
I was considering a 600 bd/ft spray foam kit. I was thinking about cutting out the fiberglass on the knee wall and using a combination rigid foam and spray. Does this make more sense? I liked this hybrid route because of the cost savings. If this does make sense, can I do a 2″ XPS board in the wall and then cover the rest of the space (and the 2x4s) with an inch of spray foam to air seal?
Back to the attic floor. The crawlspace has decking over the joist and I think it may be too small a space to comfortably work and cut away the decking. Would it be worth it to do that work or should I leave it and spray in cellulose on the deck floor after I am done addressing the knee wall? If a picture is worth 1,000 words; what would a YouTube video be? The video probably helps explain it a little better.
Hey, awesome! A video really does tell the story.
That’s a familiar looking knee wall/attic space. There’s probably millions out there just like that.
Regarding moisture – you do want to avoid the “double vapor barrier” trap, so faced insulation + board foam can be a problem. It’s not likely to be one, but for safety, it is best to use unfaced insulation or remove the facing from the fiberglass. Of course, then people will complain because the vapor retarder is supposed to be on the “warm side”, meaning facing the inside of the house. If you strip the facing and then use XPS, you’re effectively putting the vapor retarder on the cold side.
On your spray foam question – that approach would work quite well. If you’ve got a table saw, you can rip lots of XPS into strips to go between the studs then just spray over it to lock in the goodness. I’ve used quite a few of those foam kits and they’re a bit finicky. At the end of the day, I usually wish that I’d just called in a professional foam contractor to do the job! Small jobs like band joists are great, but this is a pretty extensive area. I’d say it’s on the border between DIY and call in the pros.
Personally, I prefer the approach of insulation under the roof for these types of attic spaces. While your setup is the most common, there are enough leak points that it can be a real pain to properly insulate everything. Insulating under the roof and bringing the attic into the conditioned space of the house can be much easier and more effective. I’ll try to write up a full article on this soon.
In a nutshell, here’s what I’d personally do:
1) ensure proper soffit venting and clear air pathway up to the top attic and its venting (you’ve got chutes there now, so I’m assuming this is a-ok but you should double check)
2) Install 1 1/2″ to 2″ spacer blocks under the roof sheathing to serve as an air gap from the soffit to the existing chutes
3) Install a couple layers of 2″ XPS in between the rafters, leaving an air gap from the soffit vent up above the insulation
4) Spray foam under the rafters and XPS to seal everything up air-tight. Or, just add another layer of XPS. Spray foam seals things up better, so I prefer that method.
See this link for some diagrams:
Hope that helps.
Thanks for the response. That was a helpful link. I like the idea of doing the entire roof deck. I’m not sure if it will be within budget. Using the roof deck/foam/spray method, I will have a difficult time meeting the R-49 requirement for my zone. I would be closer to R-25 with 4 inches or rigid foam and some spray. I’m guessing that combination may out preform R-49 fiberglass with air leaks.
I will probably cut out the sheetrock on the center of the roof, but I won’t be able to spray over the rigid foam between the sloped rafters (because the room is finished). Not being able to seal that portion of the roof will cause some air leakage. Is this still an acceptable method without being able to seal it up?
That little section from the top of the knee wall to the flat section of the top attic is always a problematic section because of existing finished ceilings.
The “safe” approach is to to provide continuous ventilation under the roof deck all the way up to the peak from the soffits. If you’re using rigid board foam with furring strips mounted to the rafters as spacers, you can re-pack insulation in those sloped areas and spray right from the top of the knee wall to the bottom side of the foam. That will also help the non-foam insulation in the sloped areas perform better because air won’t be moving through it.
Instead of XPS you could use polyiso board foam. The R-value can’t be beat at around R-7 per inch (there’s some controversy around the exact R-value). It’s more expensive than the XPS but if you want to squeeze out every bit of R-value, you can’t beat it.
One other thing to look at is the “whole-wall” R-value (actually, whole roof in this case). If you fill the cavity minus the air space with board foam then spray foam over that and cover the rafters with an inch or two of foam, you’re vastly improving the R-value of the rafters, which would otherwise drag down the total R-value in the normal situation because the rafters lead to thermal bridging. That’s what’s going on in the sloped section that you can’t do anything about. In the rest, as you note, you’re not going to hit R-49, but also as you note, I’d take R-30 of polyiso sealed with spray foam any day over R-49 of loose fill or batts installed normally. There’s some good charts here: http://www.monolithic.com/stories/r-value-fairy-tale-the-myth-of-insulation-values/photos
In particular, check out the R-value vs. temperature graph. Fiberglass loses substantial R-value with temperature – not a great characteristic for insulation!
I am finally getting around to installing a roof-vented bathroom fan as the first step in decreasing winter moisture in my attic. Once that’s done, I’m going to get additional insulation blown into the attic (currently R19 bats of ~40 year vintage) as a precursor to replacing our 40 year old boiler/hydronic system with geothermal some time in the next 2 years. Our attic currently has flooring down the middle (was used for storage- I don’t store things in attics). Is it better to have loose fill piled on top of the plywood, remove the plywood, or have the area under the wood dense-packed?
Ok, this is an ideal time to check for other air leaks between your living space and attic. Do NOT blow in insulation before doing this or you’ll regret it. I nearly killed my insulation guy who thought he was doing me a favor when he blew about 16″ of cellulose on top my already insulated attic, making it very difficult for me to work up there! Trust me on this.
If you want to “do it right”, you’ll locate all the wire penetrations and electrical boxes and other hidden holes and you’ll seal them while it’s easy. Then you’ll re-insulate afterwards. Also, if you ever plan on running new wires, light fixtures, etc., do it before blowing insulation in there. It’s a real bugger to work in an attic full of loose fill.
As for the flooring, you really could go any route you mentioned. In my own attic, I kept a narrow walkway between my attic access, down the center of the attic and to my air handler. I stuck batts under the 18″ or so of walkway and then have the blown in stuff covering much of it. This way, when I do need to run wires or do work up there, I just sweep the loose fill out of the way and have a safe access across the attic rather than trying to balance on the joists.
Thanks again for your thoughtful reply. I should have specified that we’re insulating following foam plugging of air leaks and placement of vent chutes (we had 36 soffit vents added last summer and covered the gable vents so that the ridge vent might work right) – I checked with our Angie’s List- multiply-approved contractor to ensure this would be done. While we may be adding a forced air system at some point with the geothermal, I’m interested in getting the insulation advantage now and I’m sure HVAC guys are used to crawling around in attics full of the junk, right? One last thing: the access to the attic is up a stair/shelf in the closet with a ~4X8 sheet on hinges as the door/hatch. Any good suggestions on how to weather-strip/insulate that to make it somewhat more air tight?
Excellent, sounds like you’re doing your homework! It’s great to have these discussions publicly so others can see the thought processes that go into “simple” things like insulating your attic. I’ve had a number of people call me and say “my contractor thought I should call you to get your guidance, but I don’t know why. I just need to insulate my attic.”
The HVAC guys should be used to it, but they’ll certainly be cursing you under their breath But this is a good reason to leave the walkway/floor in the attic. Last thing you need is a foot going through the ceiling.
Question – it sounds like you don’t have forced air now and you’d be adding ductwork etc. to the attic in the future. You might consider having registers “stubbed in” before doing the added insulation. It does make it much more of a pain (and more expensive) to install all the ducts after a blown in insulation job. You’re also more likely to have them poorly air-seal the registers because of all the insulation.
I’m sure you’ve thought of this, but I’ll mention it for our other readers – if at all possible, you’re best off installing air handlers and ductwork in the basement rather than the attic. Doing work on attic-mounted systems is a hassle. “Hassle” translates to greater cost and increased opportunities for poor workmanship. I know this from personal experience. Virtually every attic mounted duct/air handling system I’ve seen is much more poorly installed than basement mounted systems because it’s out of sight. If you can’t see it, you’re not going to inspect it and the contractors know this, so they’ll take shortcuts.
In addition, attic mounted systems are less efficient than those mounted in the “conditioned space” of the house. Not only are the systems subjected to temperature extremes, but any leaks (which all systems have) will be outside the house. Finally, the leaks will often suck in the nasty attic air, leading to a dustier/dirtier home.
On the attic “hatch” – those systems are often a hassle. If the plywood and opening are uniform, then just some good weatherstrip installed so that it gets compressed when the hatch closes can work well. Plus, a few inches of board-foam attached/glued to the attic side of the hatch. Usually though, these hatches are pretty clunky and it’s quite tough to air-seal them effectively. If yours is like that, it’s worth re-mounting it so that you have a nice flat surface and the hatch closes with a uniform gap of about 3/16″. Then a compressible “D-profile” weatherstrip works great.
Morning Ted, I just had to let you know what great equipment this Fujitsu 12RLS is once again. Listen to this. Last night temps here were in the -1 to -3 degrees C with heavy rain and freezing rain. Overnight the temp plunged to -20 degrees C and everything froze solid. It took me an hour to get the ice off my car and I thought I had broken the wipers in the process but I guess the mechanism was just iced up and the running engine helped thaw them out. This morning temps are -15 but the killer is that the wind is 40 kilometers per hour gusting to 60. This gives a wind chill well below -30C. Now Ted these are rough conditions by any measure, the Fujitsu is unfazed by it all. Its down there in my kitchen right with output temps at 98 to 100 degrees F. I’m confident those numbers are good as I’m now using a laser pistol type thermometer which I can point right into the outlet vent. The 12RLS is maintaining my kitchen and dining area at a nice warm 72F which is what the remote is set for.
The next few days promise to be quite a bit warmer getting up to the seasonal daily average of -6C.
The Fujitsu could care less.
I saw your video on the Fujitsu 12 RLS heat pump. One point you did not discuss is the level of noise produced by the appliance inside the house. How does it compare to, for instance, to the sound of a conventional gas furnace blower that comes through the floor duct, or maybe a standard window fan?
Good point, thanks for asking.
If you let it run on “auto” and don’t push it to hard most of the time, that’s equivalent to low or medium fan speed which is very unobtrusive – a gentle fan sound that you tune out. Probably about equivalent to my central heating system blower and much quieter than a typical window fan. However when it is on full-blast, it’s pretty loud. Not like a window air conditioner, but loud enough that some would complain about the noise levels.
I just found your blog…..
For the first time in my research on the Fujitsu 12RLS I have found an answer to
a question I have had (while reading Jack Leonard’s post on the 18th) regarding
output temperature of the unit at sub-freezing outdoor temperatures.
Do you have any additional stats to confirm his information?
Yep, I’ve actually got temperature sensors (input and output air) on two of my units as well as current sensors so I can see how much they’re drawing, so I’ve been able to monitor their operation continuously since installation.
The air they supply to the room is almost always between 95F-105F – quite warm even in cold outdoor temperatures. The only time the put out colder air is when they run defrost cycles, but then they turn the fan way down or off so it’s not blowing cold air around the room.
Part of the trick is that they vary the fan speed. So the temperature may be high but the fan speed is lower so the total heat delivered to the room is less as the outdoor temperatures drop. But pretty much everything I’ve seen confirms the manufacturer’s specs and it performs admirably at low temperatures.
There is one independent study that measured performance at a variety of temperatures that validates the specs
I installed a dual Fujitsu heat pump system last year and it has saved us $1000-1300 vs oil heat for the rear portion of our house vs. last year. I am wondering about the similar technology for hot water heating and for augmenting/replacing the oil fired boiler that heats the remainder of the house – as well as the electric hot water heater. For the latter, there is something called the airtap that looks interesting. For the former, I wonder if it makes sense to try and also use this technology to entirely or mostly get rid of our reliance on oil for heating the primary system – old cast iron radiators. The hot water heater in in our basement in a heated area under the master BR, and the boiler is also in the basement but in the rear of the house, under a living room/family room.
There is at least one solution – the Daikin Altherma air-to-water heat pump: http://www.spacealtherma.com/
I haven’t personally had any experience with it but there’s no reason why it shouldn’t work.
However, there is a reason why it won’t work as well as your Fujitsu heat pump – operating temperatures.
Here’s the deal. With an air heat pump like our Fujitsu, you’re raising air temperature from 70F up to maybe 100F. When you replace a boiler, you need to produce very hot water, typically 160F-180F. This is much harder for heat pumps to do. Normally, you limit hot water generation to about 120F, maybe 130F in order to maintain reasonable efficiency. Because of this, heat pump technology isn’t effective for heating water for use in radiators. This includes geothermal systems. You have to look at a more significant heating system change in order to make this all work.
As for general hot water, typically you’re running a water heater in that 120F-130F range, so heat pumps can do the trick. I have an AirTap water heater (though I haven’t used it in a while because the thermostat broke). When it was working, it was great – very efficient, especially during the summer when it could cool and dehumidify my basement. But you have to keep in mind that putting a heat pump inside the house has its downsides – in order to make hot water, it cools the air around it. So during the winter, this is essentially an air conditioner in your house running so you have to heat more to counter-effect the AirTap. So I typically switched to a different heater during the winter.
Nothing’s quite as simple as it seems unfortunately!
I am building a new house near St. Louis, MO, midwest hot humid summers, moderate winters. I have a great room with a cathedral ceiling insulated with fiberglass bats (due to the steepness of the roof). I plan to install toungue and groove pine on the ceiling, and not drywall. My question is, do I need to install an air barrier? My concern is that T&G wood will be too pourous and will allow too much heated air to escape, but I also don’t want to trap moisture somewhere where it shouldn’t be.
Ken, I urge you to read my post on this very topic: http://tedsenergytips.com/2011/03/13/cathedral-ceilings/
I’ve seen a number of homes constructed exactly in the way you describe and they’ve all been disasters. You hit the nail on the hid when you wrote “My concern is that T&G wood will be too pourous and will allow too much heated air to escape, but I also don’t want to trap moisture somewhere where it shouldn’t be.”
The short answer is – if you really want a T&G ceiling, spend the extra money and use closed cell spray foam. But really, please read the above article. This is something you really want to do right.
How does the fujitsu rls work in a damp snowy condition? right now there is so much snow (mostly slide off the roof) the only windows to see out of are in the gable ends of the house (which is where the doors are, since this happens every winter), but other than the obvious question of siting it at a gable end (so it isn’t buried in snow), is the fact of living in a cold temperate rain forest climate likely to make it unuseful due to constant defrosting?
That’s a good question. If you do have a dealer in the area, I’d ask for references so that you can talk to other people who have to deal with the same conditions.
The defrost cycles are definitely an annoying and limiting factor when you’re in the humid and 25-35F temperature range.
At the least, I would want to make an elevated platform to support the units out of the snow or provide a nice overhang that minimizes the snow buildup around the units.
I found your site last week and there is a wealth of great information here. Thanks!
I recently purchased a 35 yr old house in New Orleans. The attic insulation and sealing is insufficient. The front portion of the house is a 1-1/2 story ranch with a vented attic. There is a rear wing on the house that is a single story, also vented. The HVAC system is located above the rear wing; duct work in-circles the house through the lower crawlspace. The house has soffit vents all around, 2 turbine vents at the top of the crawlspace, 2 turbine vents in the rear wing and ridge vents on top of the crawlspace and the rear wing. Yes I said AND.
I have been through a large number of your articles and I find “Insulating walk-in attics” and “Ultimate attic insulation” to both be of interest to a retrofit project. I have some concerns I hope you can take the time to elaborate on. My roof beams are only 2×6, so I do not have sufficient space to install baffles to vent air from the lower crawlspace to the upper ridge vent and provide ‘adequate’ insulation (to the limitations of 6″ beams). Given this, sealing the attic at the roof line makes a lot of sense. Would you agree?
If I were to take this approach, I should be able to seal the attic using closed cell foam right? I am aware of the roof rot potential issues. However having an older home in a hurricane prone area, I like the structural properties the closed cell foam may provide. My concern is I have talked to many insulating contractors in the area and they all want to use open cell foam. But doing this requires me to pay them to air seal at the ceiling and I would have to adequately vent the attic, which means bridging the lower crawl space to the upper? What are your thoughts on this?
If I were to take this approach, I would remove the existing ceiling insulation, which is a mix of fiberglass batts of different thickness, most of it in bad shape (stepped on, leaked on, etc) and replace all of it with blow cellulose. My thought is my roof line can only give me 5″ of insulation, and this would be inadequate for the region.
Finally, what are your thoughts on the DIY closed cell foam kits? Obviously doing a whole house would be impractical, but if I do this my self using rigid foam blocks and/or foil-faced polyisocyanurate at the roof rafters, would the DIY closed cell foam kits be sufficient quality to bridge gaps and irregular areas?
Hi Chris, thank for the kudos.
Nola is certainly a challenging climate, with extreme heat and humidity. You face different challenges than us northerners. Up here, the big concern is allowing interior humidity come in contact with cold surfaces during the winter. Down there, you’ve got extreme summer humidity that can condense on cooled interior walls.
Sounds like a heck of a house. I wouldn’t want the HVAC in an attic down there, even one so well vented. As you asked, doing a sealed attic/insulated roof does indeed make sense in that situation. In your climate, I’d be less concerned about the open-cell vs. closed cell question. That’s more of an issue in cold climates because of condensation risk. However, the closed cell will give you the greatly increased structural integrity, as you noted, since it is essentially gluing the roof sheathing to the 2×6′s supporting them, and you get double the R-value which would be pretty important.
I wouldn’t want to go the route of insulating under the roof then again on the attic floor. This can create a “dead air space” that can be problematic. I’d scratch that idea.
Polyiso isn’t a bad approach. With its r-7 per inch, you’ll get about R-40 if you fill the space between the beams. You could then seal everything with the DIY foam kit. I’ve used a bunch of these and, as long as the canisters are warm (80-100F is great), they spray really well. It takes a little getting used to, but if you’re just doing a skim coat to seal things, you can make it go a pretty long way.
Just to make sure I didn’t miss anything in this short answer, I would strongly suggest you buy Building Science corp’s “Builder’s Guide to Hot and Humid Climates” – these go through all the considerations of doing this type of thing. You sound like a smart guy so you’d probably get a lot out of it. Or, just go to buildingscience.com and look at their papers on insulating attics in your climate.
Thanks Ted! The Building Science site is a great resource. I have read through a few articles. It seems though a lot of the articles geared to Hot and Humid Climates are targeted at new construction; a lot of the retrofit articles appear to be geared in the colder climates. You certainly understand the challenges one has in a retrofit, especially a finished 1-1/2 story, then compounded with 2×6 raters. Could you help me clarify some issues?
First, there is a lot of conflicting information regarding application of foam to the underside of the roof sheathing. Are you under the impression that this is not a problem in the south hot-humid region? In regards to closed vs. open, there are many contractors advising open cell under the roof sheathing in case of roof leaks so that the underside of the deck can breathe. As I stated before, many of these open cell contractors then explain the importance of air sealing the rest of the house attic space, of course at great expense. At the same time, the closed cell industry is stating closed cell prevents the underside of the decking getting damp even if the roof leaks, thus it’s better. The most recent article I read indicates the issue is moot as even with closed cell, the wood can still breathe enough that it would not rot unless the moisture source was constant and not repaired. So much conflicting information. I would appreciate if you know of any non-biased sources that can clear this up.
Secondly, if the closed cell really is right choice, would using rigid foam to fill the rafters cavities with spray foam in the gaps and irregular places be more cost effective then a whole spray application? I like the guidance in your forth paragraph and assuming this would be a more feasible and cost effective DIY approach. If I did this, would foil faced poly board still provide benefit, foil down of course?
Lastly, in the 3-ft of cathedral ceiling I have, should I remove the fiberglass batts and replace with rigid/closed cell? This would be difficult to do without removing the drywall, but looks like it can be done with persistence from the crawl space.
Regarding the dead space. If I can get better than R-30 in the roof rafters, then yes, I would scratch the idea. My initial thought was if I used open cell as advised by insulations installers, I would not hit R-30 and would still need to fix the insulation in the attic. I dont agree this would be dead space as my duct work is in the crawl space and very leaky. Obviously, I would have to allow for some controlled HVAC in the attic when I correct that issue as well, which I plan to. But also, I was under the impression the cellulose would not provide an air seal, so the attic would still breathe from the house, just no longer through the roof.
Thanks for your help. And again, great website!
Argh, I just wrote a really long reply and lost it. I hate when that happens!
- Foaming to the roof deck is controversial. I prefer designing a solution that is less controversial but based in sound theory. My preference is to install 1″ spacers under the deck (nailed to the rafters). Then, install board foam right up to the spacer. This provides an air gap under the roof deck so it can still be ventilated from soffit to ridge but isolate from the rest of the attic. Best of both worlds. And, you don’t have to worry about the roof deck being glued together if you have to replace any in the future. This also provides a durable surface (the back of the foam) for water to drain down if there’s ever a leak.
- Closed cell is about double the cost of poly-iso board foam, so if you’re going to DIY and pay yourself $0, you can save a lot going that route. If it were my roof, I’d install one layer of foil face, with the foil facing up, so that you’d get the radiant barrier effect directly under the roof (into the air gap formed by the spacers). Then, I’d use less expensive poly-iso board foam to fill in the rest of the rafter space. My preference would be to spray the underside of everything with foam so as to provide a good air seal to the entire assembly and reduce thermal bridging through the rafters. Doing this would give you about a full R40-R45 even with that air gap (R7 * 4.5″ deep plus R10-R15 of spray foam under that)
- The catherdralized sections are always a pain. Personally, I would sacrifice the drywall and do it from the inside. Working in the attic, trying to do a good job through that little gap is a real pain! You’ll never do it just right and get things to seal well.
- Breathing attic – you’re probably right. The main places I’ve seen people get in trouble is when they spray foam air seal attic spaces and create dead spaces with zero ventilation possibilities. That can be very problematic.
What’s your opinion about closed-cell foam sprayed on the attic-side of the ceiling to both air-seal and insulate followed by loose-fill and/or batts?
Now THAT I approve of.
It’s an excellent idea. Air sealing manually is a real bear so just spraying an inch or two over everything then using lots of inexpensive insulation (blown cellulose is my preference) on top works really well. And, if you’ve got ducts laying on the attic floor, you can just blow the cellulose over them too to give extra insulation.
Smiles from me. I got two insulation estimates for air-sealing/reinsulating the attic plus foam-sealing the rim-joists (I also need to either cover up or replace jalousie windows in the basement). One estimate was spendy (~$5K) for dense-pack under the attic floor, foam board over the floor, air-seal the cracks, loose-fill the rest, close-cell on the rim joist. The other was slightly less spendy ($3.5K) for an inch of closed-cell on the attic side of the ceiling, replace the batts already there, add loose-fill to R40, and an inch of closed-cell on the rim joists. The only bummer about option #2 is that I have to remove about 15 sheets of plywood from the floor of the attic so they can get in there and since I’m in an owner-built home, there’s about 45 nails per sheet. Thanks again.
That sounds pretty reasonable, except for all those nails! At least it’s ‘only’ 15 sheets of plywood flooring One warning when you’re doing that – wear good hearing protectors. I ruined the hearing in out one of my ears when I was doing exactly this removing the sheathing on my garage walls when I deconstructed the garage. I was pounding on these big sheets, removing the nails, and the plywood acted like a big speaker, projecting the noise back at me. After doing one panel which I banged on particularly hard, I got a ringing in my ear that’s never gone away. One moment of indiscretion lead to a lifetime of tinnitus.
My house is pretty efficient, using around 600 gallons of oil a year for heat and hot water (no AC) with pretty standard insulation and sealing. What’s the environmental break even point in terms of the tons of weird chemical foam, rigid foam, fiberglass, and silicone, not to mention replacing the sheetrock and paint, even if I were to halve that amount of oil (which I probably couldn’t)? You’ve done great analyses on other stuff so I was wondering if Ted-san has an opinion on the payback for this foam when you add the environmental cost of the foam versus the saved energy? (Obviously the oil has hidden costs, too, but let’s say you heated with biodiesel. Wouldn’t all the foam be infinitely worse for the environment? Inquiring minds are inquiring.
Hey Dave, that is a valid point – one that often results in heated debate (no pun intended…)
It’s a big “it depends.” For example, the blowing agents used in the two-part home foam blowing kits turn out to be vastly worse than CO2, like orders of magnitude worse. So using those home kits, from a “greenhouse gas” perspective can be pretty ugly. OTOH, the setups that professionals use sometimes run on compressed air, so then it’s a simpler analysis of the ingredients. Since most of these are petrochemical based, you’re definitely using fossil fuels to save fossil fuels. But, if you can take a typical house from 1500 gallons of heating oil to down below 1000 gallons, saving 500+ gallons every year, you quickly reach that break even point. With your home, you might have to switch to a different system, like geothermal, in order to significantly reduce your oil/environmental impact.
(update: see this article about new blowing agents for foams)
One of the reasons I like foam, in spite of the environmental nastiness that’s associated with it, is that it’s essentially a “permanent” solution. You generally don’t have to worry about the next homeowner coming in, pushing it aside, and ruining the energy efficiency of the house. With normal insulation, it’s fairly common to go into the attic and find that people have casually displaced it, leaving uninsulated areas that can easily double the energy loss for the entire attic.
For retrofit walls, green builders generally agree on dense packed cellulose for its high effectiveness and very low environmental impact since it’s essentially 100% recycled newspaper and Borates.
When I was doing energy audits daily, my goal was to help people prioritize remediation projects so that they could focus their efforts where they would make the greatest impact with the least effort. Usually that involved sealing up a few big holes and working on the ducts/HVAC system. The caulking/foaming/reinsulating usually came later in the list. That’s the real value of an energy audit.
Thanks for the advice Ted. I think the best part about your approach is its something I can work on in sections. How would I detail the hip roof sections. That is, I will have several rafter bays that cannot vent to the ridge using your method. Would this even be critical?
Also, regarding the whirlybids. I am thinking these should be removed. If I am venting from the soffit to the ridge, the turbines are fighting the system and should go. Would you agree? Now they do serve a purpose now because there is no ventilation through the cathedral ceiling, but doing your recommendations would fix this problem.
Regarding the ceiling, my wife will not let me. For one, we just finished re-finishing upstairs and our kids are up there. The cathedral ceiling is 3′-8″ wide and is accessible from below and above. Im just going to have to work slowly and chip at it. I do wonder though. The current fiberglass is paper faced, nailed to the rafters and sandwiched/sealed by the drywall. I would think that in these sections, the air sealing would not be as critical as much as it would above and below provided I can remove the fiberglass and preserve the paper. Im thinking a small garden tool would work for this, I forge what its called, but its hand held and has the three bent forks. Agree?
First a caveat to other readers who might misunderstand what you’re saying – energy loss or heat gain is related to the square footage divided by the R-value. So when you insulate most of your attic to R-40 but some sections remain uninsulated, say at R-1, those area let in 40x as much heat for a given square footage. So it’s always best to insulate everything or you’ll lose a disproportionate amount of energy through little uninsulated areas.
On to your real questions…
The sections that don’t/can’t be ventilated are something of a ‘tough luck’ situation. If you look at all the homes that are constructed like this, whether it be roof design or skylights, you’ll find that most have no problems because the ventilation isn’t really doing what people expect it to. In your specific case, you probably rarely get temperatures that are conducive to condensation on the back of the roof deck and when you do, it’s very likely that will be followed by sunshine and higher temperatures that “burn off” any moisture. In those areas, I would continue to treat it like the rest of the roof, with spacers and an air gap, just so that you have a little space in there. OR, you could just completely spray foam those bays because working in those bays might be a pain.
On the whirlybirds – yes. If you insulate under the roof deck, then the whirlybird would work against the rest of the system. The entire attic would need to be sealed and insulated.
On the ceiling – I see! The important thing will be to maintain the continuous ventilation space from below, through that space, up to the top attic. It might be hard to run the board foam through the space, but if you can, go for it! If you do that, you might not have to remove the fiberglass. The total R-value wouldn’t be as good as if it were all poly-iso, but just that 2″ of poly-iso would be adding R-14, so that’s not too bad. You’d compress the fiberglass, losing a little of its R-value when you work the board foam through the space but overall, it would be a net improvement.
I moved into our 2 story cap code house built in the 40′s. While gutting the house I noticed there is no insulation in the walls, there is some in the “attic” area. Everything was built with sheetrock and plaster over that. There is a knee wall the extends the entire length of the house (about 6 ft wide and 5.5 ft tall) with a small door for access. We have no soffit vents and at sometime a new roof was put on with a ridge vent. There are 2 gable vents 1 on each side of the attic. Wanting to insulate everything what is the best way to go about this. I live in Central PA, so we get a true 4 seasons. I was just planning on insulated the walls with R-13 kraft backed, and R-38 batts on the attic floor. How should I deal with the knee area? Should I insulate the roof rafters, or the walls? Should I be concerned about the ridge vent and not enough ventilation? After reading plenty of sites on insulating these areas (especially the knee area), nobody has a definite answer. If I put insulation on the roof joists (2×6 24″ centers) do I put it against the roof or leave breather space?
This can be a problematic insulation job. Are you planning on doing it yourself or having a professional insulator do the job? Some things are much easier for a DIY than others.
You’re asking the right questions though. You have to be really careful with your construction. I’ve seen a number of problems when people insulated the entrapped area above the knee wall, between the roof of the house and the ceiling of the room below and didn’t leave a ventilation gap under the roof sheathing. One big problem is the ridge vent without soffit vents. This tends to draw air and moisture up from the house rather than outside, which can lead to severe moisture problems. The gable vents will help as long as there’s free air movement from the vents to the ridge.
I’ll point you to some more pointers depending on how you’re planning on approaching it.
I plan on doing this myself, that shouldn’t be an issue. I would like to have the knee area as conditioned space, so I was planning on running the “channel vents” under the roof and insulating that way. I would then put some sort of panel board up. Granted there are no soffit vents to fully utilize these, but I figured it would keep the hot air vented into the attic, and insulation away from the roof. Since the knee area has no venting at all, should I be concerned or is this basically like a rather large closet now? The gable vents in the attic appear to be large enough, and are completely unobstructed (besides a screen).
It can get messy if you’re not very careful. I highly recommend figuring out a way of providing continuous soffit vents so that you’re providing fresh air flushing from soffits up to the ridge vent in the gap between the insulation and roof deck. Without doing that, you’re really risking a roof rot situation.
I’m guessing that the gable vents are in the small top attic, not the kneewall area that you’re describing as a large closet?
I’ve got an article on this very topic. You may also want to review some of the material on the Building Science website. Here’s one such article and there are others that are worth reading. I’d hate to see you spend a lot of effort and end up creating a problem.
Thanks for the info Ted. And yes you are correct the gable vents are in the attic above the knee area. The problem is there is no way to put soffit vents in, the roof joins the wall with no overhang. I’m not sure if it matters much, but the roof is all 1×6 tongue and groove, then the standard felt paper with shingles. The articles you sent are great, I came across them before, but almost all assume you have soffits or an overhang so you can add them. It almost seems like I’m going to have to give up trying to make this a conditioned space, and just insulate the knee wall and floor.
I’ve run into construction which precludes soffit venting, including half of my own home. The most important thing in this case is to do whatever you can to prevent warm, moist air from the inside of your home from coming in contact with that cold roof deck.
This is certainly possible – think about all the older homes without soffit vents. What’s happened in modern homes is that they’ve gotten considerably tighter, so the moisture builds up rather than being flushed out through all the leaky windows and so forth. When that happens, it works its way up through the house and escapes wherever it can, but in much higher concentrations than it did in times past. With your construction, the ridge vent actually helps to suck air from the house into the attic spaces, increasing the likelihood that moisture problems will arise. Because of this, you have to be especially careful.
This is why, for this construction, I greatly prefer spray foam applied directly to the underside of the roof deck. The foam hermetically seals the area so that warm moist air simply cannot come in contact with the cold roof deck. At least if it’s done properly.
Since you’re looking at a DIY solution, you’d be best off with a solution like rigid board foam applied under the roof deck, with a bit of an air gap – about 1″. Even without the soffit vents, the T&G planking used as decking will be somewhat porous, allowing moisture movement out of the space, albeit slowly. So if it were my roof, I’d use at least one layer of 2″ dense foam board (either blue or pink stuff, not the white stuff). Then, I’d seal the joints where the board is in between the rafters, so that air can’t sneak around the edges. If you do that, you can pretty well seal the easily accessible areas of the roof from the attic. It’s time consuming but doable as a DIY if you pay attention to details.
The trick is where you can’t access the roof any more, where it’s hidden by the ceiling section resting on the knee-wall. Unfortunately, that’s also usually where problems arise because the moist air wants to go up through those channels and out the top attic. One solution (which is somewhat heretical, but logical), is to securely block off these areas using more of the rigid board foam, cut snugly then sealed around the edges. This blocks the moisture from being drawn strongly from the living space up to the top attic. I would still use vent chutes under the roof deck, if you can get them in there, so that there’s a continuous channel with the space in the lower area as described above. Then insulate under this (i.e. behind the sloped ceiling of the room under the attic).
The one case where even this still may fail is if you have a tongue and groove ceiling in the room under the attic. Those ceilings allow so much air movement that it’s virtually impossible to fix them and prevent mold and wood rot in some climates.
I hope this gives some idea of how you might attack the problem. It’s definitely one of the hardest ones in practice to do in a way that won’t blow-up on you in years to come.
Fujitsu heat pump
Hello Ted, I took the opportunity today to upgrade the insulation on the tubing on my 12RLS. I went to my local building store and bought the common black foam pipe insulation normally used on water heater piping and a/c installations. I’m not sure how this will stand up outdoors, but I noticed that the neoprene used by the installers in Dec. has already started to show signs of deterioration.
Sun damage I guess, veining and checking. Anyway I bought the stuff with 3/4″ ID and it fit quite well over the original neoprene and I just taped it with black electrical tape, a pretty neat job if you don’t get too close. I know that there is some kind of vinyl channel that can be used over the insulation but I can see that it wasn’t very practical in my case and would have meant lengthening the line in order to do it. The installers had left about 1/2″ of pipe inside the small cowling where the lines enter the unit. You know all they had to do was remove the cowl and they could have easily have insulated this easily. Hard to get good help these days. I didn’t want to remove the cowl so I just stuffed the area around the connections with white packing foam, which should not be affected by moisture. Well Ted how long I wonder can I expect this insulation to last?
I’ve got the softer black insulation on mine also. It’s supposed to be better than the black foam but both weather poorly in my experience – UV kills most rubbers/plastics so whatever you use, it should be protected from direct sunlight. Mine was installed inside a channel that’s like a gutter downspout. I’ve also used the silver foil bubble wrap to protect the foam insulations.
I have completely gutted and renovated a 100 yr old house, I need your opinion on insulation.
My upstairs (bedrms) has a partial cathedral ceiling, in other words, 5ft knee wall, 6ft sloped ceiling,
then horizontal ceiling. Can I completely fill in the 6inch sloped ceiling with spray foam, just 6ft,
not to the peak, Then put celluouse in the attic, The question is do i need venting from the soffit?
I do have a ridge vent,(new roof). But not sure if thats enough.
There are a couple of schools of thought on this. You might check some of the other discussions we’ve had recently. At the bottom of
I discuss exactly this type of situation.
A couple questions on the specifics of your home:
- do you have an attic space behind the kneewall?
- if yes, is that space vented? Probably not in this vintage home.
- Does the top attic have anything besides the ridge vent? That is, does it have gable vents or any other way for air to get in? If not, the ridge vent isn’t doing much good. In fact, it might be bad.
In general, that little space of sloped ceiling that you’re talking about is one of the most problematic features shared by many homes. If you can spray closed cell foam directly to the underside of the roof deck, you’re usually pretty safe sealing this space up.
Specifics however require a closer look at your home and it’s construction. You also want to take into account the climate zones. Very cold climates have different considerations than very hot-humid ones. In our climate zone, you get hot-humid summers and cold winters, so you have to be pretty careful about issues that can lead to condensation during the winter. However, as noted, closed cell foam applied directly to the underside of the roof deck usually eliminates these worries.
I read in your reply from a year ago that you have Fujitsu Halcyon splits in your home. I, too, have one of these. Have you ever tried to clean the blower fins? I have found that mold has accumulated on the fins of my unit to the point of large masses after 10 years of normal use. I can’t find any company guidance or diy tips for accessing this blower.
I haven’t looked at mine closely, though all my indoor units were replaced recently due to a power surge.
In general, dust accumulation is expected. This happens worse during air conditioning season when the fins are cold and get wet with condensation, catching the dust. Unfortunately, that also creates growing conditions for mold.
The best thing is routine maintenance – a couple times a season, thoroughly clean the air intake filters and use a shop vac (with a soft brush attachment) to clean the fins. The fins are *very* delicate and you want to avoid damaging them. You can also use a high power blower to force air through the system, dislodging dust and other debris.
When it’s gone as far as you’ve noticed, it likely requires more aggressive cleaning which likely requires dis-assembly and the use of solvents, something I’d leave to the pros. It’s pretty time consuming so it won’t be a cheap operation. If you look on YouTube, you’ll find several videos showing the process – it’s messy and time consuming. Personally, I wouldn’t do it as a DIY job if it’s gotten to this state because you might turn a $250 job into replacement of the unit!
Thanks, Ted. You are right about the DIY part, but dis-assembly seems to be the only way to access the fins on my blower. The only way to reach it is through a wire grille which makes it impossible to keep the wheel from spinning as I try to brush the build-up off the fins.
It unfortunately does look like it needs dismantling. I wonder if you might be able to do it with air pressure alone? Probably not.
When I’ve seen techs clean the fins, they use a foaming solvent/cleaner which then has to be flushed with water. A really messy operation when done indoors!
I have found a workable alternative to dismantling the unit. I ordered a large brush that is made for cleaning mortar from the holes in the center of bricks as they are being laid. The brush handle is 12″ long, made of heavy, twisted wire. Brush bristles are made of stiff plastic and 5/8″ in diameter. When I insert this brush through the wire grid between the blower and the back of its housing, I can wedge the brush so that it forces its bristles between fins, dislodging the build-up of mold and dust particles. By rotating the brush, the blower wheel can be rotated to get to all the fins.
Wow, good job!
Just be careful of those thin aluminum fins. They’re really delicate.
Hello Ted, I read the posts about cleaning the 12RLS with interest, when should you do the first cleaning of the filters, or do you replace them? I assume you have to take off the moving cover to get at them?
Jack, the filters pull out and can be washed. They hidden behind the motorized front panel.
Find the manual on the manual page and look at the section on cleaning (P-13).
I keep an eye on it and clean mine when there’s obvious dirt building up.
I have a roofing/insulation question. I have a low pitch roof (1.5), live in the Boston area – the new roof needs to be black rubber. My roofer wants to put foam board under the membrane and above the sheath and then keep the vent under the sheath. Between the sheath and my ceiling is 8 inches (cathedral flat roof).
My question is with the rigid foam above the sheath (r20) does it make sense to fill the 8 inch cavity with something (open cell spray foam, dense pack, etc) or should I respect the original roof design (soffits, no ridge/gable venting)? Should I try something else? I’m also trying to avoid taking the ceiling down as well. Will insulation above a vent do anything for me and my house?
Love your blog – it’s been incredibly eye opening!
Great question! That’s a tricky configuration, one that’s common around Philly also. I’m hesitant to give too much advice without seeing the exact configuration of the roof and the rest of your house. However, there are some general concepts that you’ve hit upon that are worth discussion.
In particular venting between the roof insulation and the living space is a bit counter productive, but not totally. What you’ve described, with roof membrane then insulation will help considerably to reduce heat drive into that space underneath. Without the insulation, the space would probably be something like 130F-150F. Insulating under it will keep the space much cooler. As you noted, venting under that will then allow outside air in so you won’t be insulating from the outside temperature, whether it be 0 degrees or 100 degrees. Without good insulation, your ceiling will be basically the same temperature.
On the other hand, if you didn’t vent that space then any moisture that gets into the area could pose a condensation risk. If you were building a new home, I’d say to spray foam directly to the top surface of your ceiling (i.e. the attic ‘floor’). That would minimize moisture movement and allow you to conventionally vent the space between getting the best of both worlds.
A couple other things – if you’re allowed to use white rubber, you’ll be much better off than black rubber. I inspected an industrial roof like this and was amazed at how cool it stayed.
Also, it sounds like you may have the opportunity to open the roof if you’re considering the possibility of spray foam. If you can do that, that would be my first choice. As noted above, I’d foam right to the top of your cathedral ceiling material.
To put this all in perspective, think about the “jacket” analogy. If you leave your jacket open during the winter, you get cold because there’s nothing stopping the cold air from sucking the heat from your body. So you zip up the jacket to keep the air out. Now you stay warm. Same with your home. Venting between your living space and the insulation is like leaving the jacket wide open.
Good luck with your project. I hope you have a really comfortable and efficient home after that!
I’ve been reading your blog all evening, trying to absorb enough info. I think I’m going in a good insulating direction, but wanted to run my thoughts by your expertise!
So recently bought a 1.5 story ranch with two upstairs bedrooms (mostly under adormer) in northern NJ. In one upstairs bedroom, we removed the contact papered over wood paneling, thinking there was sheet rock underneath. This turned into a bigger job than expected, because only 1/3rd of the room was sheetrocked. I’ve already put in place the sheet rock for the entire room (except a piece or two). A guy at work heard what I was doing, and is strongly incouraging me to upgrade the insulation (sad looking R13? between 2×6 roof rafters). So now, I’m trying to figure out if we have the budget to insulate well enough to make a difference. Or if there is a two phased approach I can take.
The roof has soffits along the eaves but no vent at the top of the roof. And due to the roof lines, I don’t think the soffit’s air flow would even hit this portion of the roof. So I’m wondering if this is actually a poor unvented section. The other bedroom has one knee wall exposed to the soffits/uninsulated garage (which I need to tackle later).
I was thinking of taking down the new/old sheet rock in this bedroom, sealing the rafters with rigid foam blocks at the top/bottom (and foam sealing), putting in fiberglass or mineral wool batts, lining over the rafters with 1″ (?) polyiso foam, and then recovering with sheetrock. I’m thinking it would give me ~R30. Not exactly the R39 I would like, but it wouldn’t eat up the headroom of the sloped walls (this bedroom is primarily sloped) and the poly would create a thermal break and air seal.
Do you think this would cause issues in the long run?
Great questions. Increasingly, people are having similar issues/questions, so I’m happy to try to give you some pointers.
Ideally, you’d attack this problem before putting up the sheet rock as it’s much easier to do a proper job, so your thought about taking down the rock is on target. If you’re going through that trouble, you might consider having a foam company come in and just fill the cavities with spray foam, then re-rocking the ceilings. The advantage of this is that the foam will minimize the chance of rotting out your roof deck if moisture gets in there. You are talking about blocking out the areas to minimize the chance of this happening, so you could probably get away without the full spray foam job, but I’m always a little nervous about suggesting approaches that require perfect craftsmanship in order to work. But what you describe would be a pretty decent way to go if you’re going to do the work yourself.
A different approach that would make the roofers and building inspectors happier would be to create an air channel all the way from the soffits up to the (currently non-existent) ridge vent using furring strips along the 2×6′s, then build the channel with 2″ poly-iso foam. You could then fill the remaining few inches of cavity with batts of your choice and complete as you describe with 1″ polyiso and sheetrock. That would give you 3″ polyiso plus about 3″ batts for the same total of about R30 AND give you an air channel under the roof deck. This would be a pretty conservative approach that would give you decent insulation and a safety net for your roof.
The main important detail is that the channel would need to extend all the way to the soffit vent and be sealed so as to minimize the chance of pulling moist air from the house into the vent. I’ve seen that type of thing cause serious issues with walk-in kneewall attic spaces. Lots of moisture getting sucked into that space comes into contact with the cold roof = mold and rot.
The key thing is to stay conscious of what the moist air wants to do. It wants to go up and it wants to condense on cold surfaces.
I’m definitely leaning towards your conservative approach. The air gap would remain, just in case. I’ve been trying to figure out if any of the soffits vent into this space, but I don’t think so. But there was a huge air gap there now, and no moisture issues and we definitely don’t want any in the future. The polyiso sandwiching a batt would definitely be decent insulatio not quite R50 but its a lot cheaper than spray foam. Thank you for the help.
Still haven’t decided what to do…mulling over the costs and returns
But I came across some discussions regarding double layers of polyiso foam with batting in the middle (like I was leaning towards -using roxul and at least one foil lined polyiso layer). One person mentioned using XPS instead but others said not to have the layer that I was planning to be for the venting. A concern was that over time, air would be introduced despite the sealing and moisture would be trapt between the layers. In theory I can see this happening and even probable.
Do you have any thoughts on this? or on improvements?
If I get rid of the poly next to the venting (which I’m almost 100% does not connect to the soffits in anywhich way) would there be too much air circulation to get a good R value out of the Roxul? Or can I wrap the Roxul in an air barrier like Tyvek?
Double layers can be problematic because there will always be air leakage which will carry moisture. The first critical question is whether the air will come in contact with any surfaces at or below the condensation temperature. You mentioned using a thinner inner layer and thicker outer layer. Typically, the rule in our climate is to have no more than half your R-value inside of the outermost insulating condensation plane. In your case, that would be the insulation closest to the roof.
So, for example, if you used 2″ polyiso under the roof (as the vent channel), you’d get about R-14 there. Then, you’d have R-7 for the one inch inside, next to your ceiling. And a few inches of Roxul could push you up a bit above the R-14 in your outer layer. So it’s somewhat iffy.
The second critical consideration then is, “what happens if liquid water gets into this cavity between the two layers and is essentially trapped”. This can occur from condensation or roof leaks. With a space like this, if this water built up over time, it would definitely cause problems. Now I remember why I normally just recommend spray foaming inside the vent layer!
Here’s an alternative that would eliminate both these problems – eliminate the Roxul layer and add layers of polyiso or other board foam of your choice. I didn’t recommend this at first due to the added labor. But suppose that instead of:
– Air gap (1″)
– Polyiso (2″ = R-14)
– Roxul (<3" ~ R-10)
– Polyiso (1" = R-7)
(total insulation R ~ 31)
– Air gap (1.5")
– Polyiso (2" = R-14)
– Polyiso (2" = R-14)
– Polyiso (1" = R-7)
(total insulation R ~ 34)
Because the layers of polyiso would be sandwiched, the volume of air and associated moisture in between layers would be essentially nil. The top air gap has been increased which also improves the ventilation under the roof deck.
Usually I don't recommend this method simply because, with the added labor, you may as well get it spray foamed. You might then do:
– Air gap (1.5")
– Polyiso (2" = R-14)
– closed cell spray foam (2" = R-13)
(total insulation R ~ 27)
The R-value isn't as good but the spray foam seals everything air-tight so there's almost no chance of interior air-borne moisture getting above it. Also, this eliminates the inner poly-iso, reducing labor/material costs as well as the possibility of creating a double vapor barrier and the associated issues, though this is much less of a problem now that you have R-27 on the "cold side".
Everything simple, gets complicated!
I really appreciate your help.
Considering we’re not planning on moving for a very long time, we’re invested in making sure the insulation won’t be hurting the house.
What you just suggested is actually what I had thought about two weeks ago. LOL Full circle. Well maybe it wasn’t thinking to ventilate it…probably not.
I don’t mind the extra work (although less would be a plus!). This is a small room and the only room we’re doing at the moment.
Spray foam isn’t an option (at this exact moment) because of the price and I doubt someone would bid a job this small (less than 250 sq ft of wall surface).
I started looking toward roxul because it seems mold/bug/compression resistant. And the price is great. money always talks. That’s the point I’m at now, comparing prices and r values and mulling over diminishing returns. And I’m cringing at the figid foam costs for this small space. If I could just slap up roxul 5.5″ roxul and a 1″ polyiso I’d be so happy (R value ~29 – if ideal) but the whole venting issue put a crimp into that idea.
Thanks again. This is keeping me up at night and I need to get past it. LOL
Roxul is a good product that many “green” builders have adopted for the reasons you mention, so I wouldn’t discourage you from using it, if done in a manner that will ‘do no harm’ to the house. The most important thing, beyond R-value and everything else, is that what you build should be durable and not cause problems.
So let’s take a step back.
The problem with fully filling the cavity is that the batt insulation, in contact with the roof deck, provides minimal ventilation potential and traps any moisture that condenses right against the roof deck, rotting it out over time. Essentially, the batt is like a wet sponge – leave it sitting on the countertop and the top (air side) dries out but the bottom, in contact with the counter, stays sopping wet and nasty. So we want to avoid that.
In older homes where you often see fully filled cavities and insulation right up against the roof, often the roofs were constructed differently. You might have had wood or slate shingles mounted on slats nailed to the rafters. The system was “open” and vented right to the outside. This washed out any moisture that got that far. As roofing switched to plywood with tar paper then OSB and rubber membranes, we created impermeable surfaces that trapped in moisture, so we had to create a ventilation space underneath to flush out the moisture.
In your case, you mention that you don’t have soffit vents that would ventilate this space just below the roof deck. If possible, it would be really good to address this and install matched soffit/ridge venting to provide an ample air path through. The Cor-a-vent product is great for this. I used it on my own home in one roof section that is fully vented. But sometimes this isn’t possible, so you just have to make the best of it.
In “real life”, I have only seen issues with unvented roof cavities under a few conditions:
A) recessed lights in a cathedral ceiling. Almost every one of these installations leads to a rotten roof because the recessed lights are never truly air/moisture sealed nor (even if rated air tight). Even if they were, they wouldn’t be installed air tight. So they provide a direct path for water vapor to flow up into the space where it immediately condenses on the cold roof sheathing leading to mold and rot.
B) wooden slat ceilings. Often aesthetically attractive, this construction provides no air/moisture barrier. Even with plastic under it (usually filled with holes). Same problem as (A). Even worse when combined with (A)
C) The fully insulated space between ceiling and roof opens behind a kneewall that is used as attic storage. Since these spaces are open to the house and usually not ventilated, moisture gets into these spaces and follows the path up through the roof cavities, being sucked through by a ridge vent. To make matters much worse, in many of these cases, bath fans are venting into this space.
Note: the problems exist and are often made worse by ridge vents because air going out the ridge vent has to come from somewhere. That somewhere is usually the interior of the house. So often I’ll see these problems arise after a well meaning roofer installs a ridge vent on a roof that has functioned properly for decades without a ridge vent.
All of these problems are due to large amounts of INTERIOR moisture ending up in the cavity. That moisture will condense on the first cold surface it comes in contact with, which is usually the underside of the roof deck.
Your idea of internal poly-iso, running between the rafters and the sheetrock is a good one. It will greatly reduce thermal bridging through the rafters, increasing the overall R-value far more than you might think. In addition, since they’re large sheets of foil faced insulation, they will stop virtually all moisture from moving from the house into the cavities from the house. Just don’t poke holes in it (recessed lights). I would NOT eliminate this layer. It’s good insulation at the right place.
Above that, you could put your Roxul. Again, I can’t recommend fully filling the cavity so you’re best off with less R-value and an air-gap than more R-value and insulation in contact with the roof deck. Especially if you have the inner layer of polyiso.
So there’s your simplest, lowest cost, safest solution. Sheet rock => poly-iso => Roxul => Air gap => roof sheathing
If you wanted, you could use 2″ of polyiso instead of the 1″ you originally proposed. You’d lose a little more headroom but you’d add R7. You’d also have to use longer screws for the sheetrock. It’s a little more of a pain to install but your overall R-value ends up pretty good.
I have a 2 story home built in the early 1930′s in the midwest. The first level is brick and the 2nd story is stucco. It has a full basement made of stone. I have started the process of making sure it is properly insulated. The first level with the brick seems to do pretty well as is. The second story however is a freezer in the winter and an oven in the summer. The second story has a mix of knee walls cathedral ceilings and regular walls.
I’m not sure where to start with insulation. Im preparing to remove most of the walls ceiling and the floor however there is one room with the original hardwood floor in place. I know for fact there is no insulation underneath this floor and the ceiling below is original plaster and lathe. Each stud bay end of this floor opens up into a small knee wall with little to no insulation. In the summer the floor of this room is HOT. Would putting rigid foam in the ends of the stud bays be a good idea? Or would I essentially be making a terrible place for moisture to gather since its not vented and there’s the original plaster and lathe below?
On my knee walls there is no venting from the underside eaves . Im guessing there is no point in adding any underside baffles on the roof deck.
I plan to take my time and use fiberglass while sealing all the holes I can find. I plan on using unfaced fiberglass and putting my own vapor barrier under the sheetrock. Is there any risk to the life of the stucco by adding a vapor barrier. The house doesn’t have much if any of a moisture problem currently and I sure don’t want to make one by doing something wrong.
Your website is by the far the most informative I have found. Any guidance would be greatly appreciated.
Wow, so sorry for the long delay. Your question slipped through the cracks.
Revitalizing homes of this vintage can be very tricky. Sometimes, even great plans can result in unexpected problems. Let me try to give you an overview of what problems can happen and why they do. I’m going to start with a general discussion then move on to some of your specific questions…
First, remember – warm air carries more humidity than cold air. This is one reason why older, less insulated homes often have fewer moisture problems than better insulated homes do. In the home with less insulation, the warmth from inside helps warm the air in areas like attics and behind knee walls. This then helps dry out and carry away moisture that might otherwise accumulate. Now, suppose you add insulation and it does its job. Then these attic and other areas, that are “supposed” to be cold, are. But now, the moisture isn’t driven out, leading to moisture related issues.
Second, often these homes are very leaky. In conjunction with the first point, this leakiness can help flush out moisture. This is also why these homes can be very dry in the winter. The cold, dry winter air comes in, flushes through the house and out the leaks. This is horrible for comfort and energy efficiency but it can help to flush moisture from where it shouldn’t be.
Put these together: if you tighten the house and add insulation, you’ve made it much more important for the house to be engineered properly. From your questions, it sounds like you understand this, but it’s important to repeat this for new readers. I’ve run into a lot of problems created by well meaning contractors or DIY’ers, who insulate and air seal without considering how the house acts as a complete unit.
Since most problems of this sort are related to moisture entering cold spaces (usually attics in the winter), it’s critical to do a great job air sealing between the living space and the attic. This means any access doors or hatches need to be carefully weatherstripped along with hidden “holes” like electrical boxes, recessed lights, leaky ductwork etc. Doing this single thing can make the house significantly more comfortable and efficient even before adding insulation.
Leading to your question about blocking off the joist bays – this is usually a very good idea. You’re right to consider the possibility of moisture buildup, but if you don’t have holes poked through the plaster, then the moisture movement through painted plaster is pretty minimal. Given the age of the house, you’ve probably got about 50 layers of paint, so that’s the least of your worries. Just patch the holes because vastly more moisture is carried by air movement than moving through the ceiling itself.
Regarding the area of the roof behind the knee walls – I’m always hesitant to suggest putting insulation right up against the underside of the roof unless it’s closed cell spray foam because moisture will get in there and the insulation can trap it against the cold underside of the roof. In the “old days” this often worked because roofs were usually very “open” – they had slate or wood shingles attached to nailers so the air circulated well. But now, most of those open roofs have been replaced by plywood or OSB covered by either a rubber membrane or heavy paper. This is vastly more susceptible to trapping moisture. So I would be very conservative in how you insulate the roof.
When putting up new walls and using vapor barriers, I would consult local building codes. Position and use varies considerably by climate. I will say, many building professionals recommend avoiding vapor barriers since they often don’t work in the way they’re intended and can cause problems with inappropriately applied.
Hope this helps and sorry for the delay in getting back to you.
We are considering a Fujitsu Ductless mini-split for our primary heat source. We have gotten a few estimates and a few different opinions on what to install (mutli-zone vs. mutiple single-zone units). We live in CT and have a 2 story 1940′s brick cape with full dormer (3 bed/1 bath upstairs), full unconditioned basement. The house is about 1200 sq. ft. Our current heat source is an oil-fired boiler with steam radiators. However, the boiler has a hole in it and needs to be replaced. Money to replace (and run) our heat source is a huge consideration.With oil prices as they are, we are having a hard time time trying to justify replacement. Here are my questions:
-Is a mini-split a viable option as the only heat source? The average low in January is 18F and we get few days of near zero lows.
-multi-zone vs. multiple singe-zone units? The single zone units seem to be more efficient, but we are a little concerned about the air flow into the upper bedrooms. (The upper unit would be in the corner of the master and feed across a short hall into the other bedrooms) We like the idea of being able to have mutple wall mounts upstairs to avoid any potential cold-spots.
-Any concerns about the units operating in wet or blizazrd conditions? Would we be able to negate some of these effects by having a roof overhang above the unit?
Mike, those are all great questions.
First, with heat pumps, you always want your home as well insulated as possible to ensure the best comfort. In the old days, heating systems were vastly oversized for the home, so they were able to comfortably combat poor insulation, and drafty construction. With heat pumps, you’re designing much closer to the capacity of the units, so comfort will suffer, especially during cold, windy weather, if the home isn’t tight and insulated.
The Fujitsu and similar heat pumps have a fully variable speed compressor, which is great – they adjust output to the need and can squeeze more heat out than the older units. However, they can’t work miracles – you really want one unit in each space/bedroom to really do the job. That can get pricey with lots of single units, so sometimes it’s worth getting the multi-headed units and give up some efficiency.
I always recommend a backup heat source to help the heat pumps on those bitterly cold days. In conventional central heat pumps you use electric heat strips. For mini-splits, you install electric baseboard heaters. Yes, it’s way less efficient (4-5x less than these heat pumps!) so you only use them when needed. But when you do need them, you’ll be glad you have them! An alternative is to use those little, inexpensive plug in oil-filled electric radiators. Those are only about $50/each, so you can get a few for winter backup and use them as needed. Then, after you have a winter’s worth of use and you see where you needed to use the radiators, you have real electric baseboards installed in those rooms.
Note – in some jurisdictions, the building officers *require* installed backup heat for heat pumps. This is actually a good thing. Think about the next owner of the home. If they don’t know about the portable heaters, they’ll suffer in the cold thinking that the mini-splits aren’t doing their job. Then some contractor will sell them a whole new heating system and maybe rip out the mini-splits. So I really prefer a long-term solution that survives along with the home.
Thank Ted. As usual great information. We do have space heaters (1 oil-filled as you described and an infrared tower, probably another as well to avoid having to move them often) to use as back-up for the time being. We do plan on installing a permanent back-up.
Sounds like you’ve got the bases covered. I hope to hear from you after your project. Sharing your experiences would be great for others. A lot of people have wanted to do exactly what you’re discussing so learning from your real-world experience would help many others.
Hi Ted, I came across your video on heat pumps while I was researching the Fujitsu RLS 2 system and found it interesting. I live in southern Maine and have since installled two RLS 2 systems and have a third on the way. So far they have performed better than expected although it has only been down to 22 F. I have a propane fired hot water system and I know that when it gets really cold (this is Maine after all) it will have to take over but the mean temperature here from November through March is around 30 F and I believe that the heat pumps will provide at least 80% of my heat requirement. The expected savings should be $1500 per year which amounts to a pay back in 6.6 years at last years propane price. It should also extend the life of the boiler! The best part is that I can sit in my living room and it’s 70 F and I don’t even think about turning the thermostat down and a fire in the woodstove will be for ambience, not survival. Thanks for your informative website and videos and I hope this blurb will be of interest to your readers.
That’s great “real-world” feedback Gerry. There’s nothing like hearing about how these systems actually work for people. Thanks too for mentioning your potential cost savings. That does help to put things in perspective for people. I’m doing the same thing, displacing my oil fired boiler for most of the winter. Nothing like telling the oil man “nope, I don’t need a delivery, call me next year!”
I will let you know after the heating season how it all works out. The third heat pump should be installed soon and that will cover the three somewhat seperate sections of the house. I think that these heat pumps are the wave of the future but it will take time to get folks in Maine to realize that you don’t necessarily have to burn something to produce heat. Geothermal exists here but it is very expensive, way beyond what I could afford. There was a company that made cold climate air source heat pumps in Bangor ME but they were unrelialble and the company went out of business. Fujitsu seemed to be the way to go but Mitsubishi makes very efficient units and I’ve noticed LG units on a building here also. We’ll see what the future has in store!
Hello Ted, I just read your post on cleaning the Fujitsu filters, which I did about a month ago but I did not see the pleated filter you describe? How do I find and clean it?
Here Jack – I couldn’t insert the images in my reply so I added a new post.
Ted: about 80% of my business is installing Mitsubishi heat pumps for heating/cooling in a cold climate. I liked your video on heat pumps but I can probably educate you a bit on their application.
Call me at your convenience.
John Onstad, CEO
Santa Fe, NM
You could do even better and submit an article for me to review. Your knowledge and experience would be appreciated by my readers.
We have a humidifier connected to our heating system. For the last couple of years now, when we turn it on early in the season, and then a subsequent few more times, we get a smell that reminds me a pencil shavings. We’ve had the H&A/C people in to check it out, but they don’t ever smell it and have nothing to offer in the way of an explanation. It does eventually go away, but my husband is concerned it might be unhealthy for us and our five-year old. Any ideas? I appreciate your pondering this!
Karen – central humidifiers can be a breeding ground for all sorts of nasties because they provide a perfect breeding ground for them.
These central systems have a removable cover that gives you access to the humidification element. Often, they’ll have something like a sponge that gets soaked with water in a chamber that the air runs through. This chamber and element should be dry during the off-season otherwise it will likely be quite disgusting – full of slime and mold. It’s beneficial to inspect this before activating the humidifier at the start of the season. You can then clean it out and replace the element as necessary.
Here’s a link to the manuals for one of the most popular brands of humidifiers. It’s worth reading through the maintenance section of the manual.
First off let me be the first to wish you a happy new year. Thank you for the great information provided on this site and a way to post questions and your replies.
A little back story before my question… I have recently purchased a two story home in California and I have an unconditioned attic with gable (I think that is what they are called) vents, no soffit or roof line vents, pretty standard here. It gets hot here in the summer up to 118 deg. and I’m sure it’s much toastier in the attic. I have a central AC outside and a large heat pump in the attic with all the duct work. I’ve been doing my own energy auditing because the whole house is electric, there is no natural gas in my city and I don’t want to retrofit to propane appliances. Up in the attic I’ve been locating air leaks and deficiencies with the blown in cellulose insulation easy fixes, but after going through your site (and others) I understand now that the ducting in an unconditioned space is a lot less efficient due to the differences between inside and outside temps.
My question is this, would it be a good idea to use closed cell spray foam the underside sheathing of the roof in the attic to act as an insulator, vapor and radiant heat barrier? If it’s okay to do are there any pitfalls to this like leaving a space near the eves and roof line for air to vent around? Would you recommend something else like just installing a radiant heat barrier on the rafters under the sheathing?
I have read in a conditioned space this is good, but not a lot of info if this is acceptable or even good practice in an unconditioned attic. I wasn’t looking to retrofit my attic to a conditioned one either. The roof isn’t high enough to stand in. I’m just thinking of this from an energy savings point of view.
My main goal is to reduce the temperature inside the unconditioned attic and do it so that I don’t cause any future issues like rotting the sheathing.
I appreciate your feedback and insight.
Best regards and good fortune,
Hi Arthur – what a great note! Thank you.
It sounds like you’ve been doing your homework and you’ve got a really valid question/concern.
The short answer:
If you insulate under the roof sheathing, you’re turning the attic into part of your living space so the insulation job should be complete – no more venting of any sort in the attic and you must insulate/seal every surface that is in contact with the outdoors. That means under the roof and along the gable ends.
If you use a sufficient amount of closed cell foam, you really shouldn’t worry about other insulation like radiant barriers. Just use sufficient foam – typically about 6″ thick, on all surfaces exposed to the outside. The actual amount you use is a point of some controversy. Building code in most areas calls for about R-40, which would be about 6″. However, this can get pricey since you pay by the thickness sprayed. A lot of contractors argue for using less than code, asserting that you’re reaching a point of diminishing returns. For example, 4″ gives about R-25 (which equals 4% heat energy transmission). 6″ gives about R-38 (= ~2.6% heat transmission). So you’re paying considerably more to reduce the energy loss by about 1.4% – not a heck of a lot.
On the other hand, the underside of the roof gets really hot, so the amount of energy savings are amplified compared to, for example, the walls of the house. So that 1.4% could be meaningful.
Sometime the building inspectors allow this, sometimes not. If I were you, I’d check the options and pricing and decide based on your overall goals.
Note too that once you’ve insulated in this way, the cellulose on the attic floor is extraneous and could even be harmful. Typically, it is recommended that you remove that insulation so that you don’t have a pocket of air (the attic space) between the roof and the ceiling of the living space. You really only want insulation in one location.
As for roof rot etc., the roof sheathing is less prone to moisture damage doing this because most roof damage is due to interior moisture moving up from the living space and condensing on the cold roof sheathing. When you spray foam the roof, you’re making it impossible for this moisture to get to the wood.
However, many people worry about roof leaks and rotting from the top. This is far less likely but still possible. If I were you, I’d periodically inspect my roof for missing singles or other things that could cause water intrusion. The most common place is around flashing, like roof vents and chimneys.
Hope that helps,
Good luck with your project!
Yeah I’ve been doing my homework and you gave me the answer I suspected. I guess have to think about this and see if I want to make it a conditioned living space or just leave it as is and seal around the canned lights and then add some more blown in insulation.
I’ll look at overall cost of each, pros and cons, and then go from there.
Any idea on the potential energy savings in an unconditioned vs. conditioned space??? I’ll google it and see if I get any results that seem valid. I know that there are probably too many variables with that question that make it hard to answer.
I appreciate the prompt reply and wish you a great week.
Even if you’re not going to use it as living space, your AC in the attic will be much more efficient if it doesn’t have to deal with 140F temperatures. Plus it will last longer because motors and electronics really don’t like hot conditions.
Regarding how much is “much” more efficient, it depends on too many variables as you note. For example, I’ve seen duct systems that leak on the air intake side (sucking in hot attic air) that lose about 50% efficiency. Unfortunately, this is more common than you’d think. Any little leak in the attic ductwork is amplified by the extremely high temperature air. Worse, if you have high humidity, that humidity gets sucked in and distributed into the house, making the AC work harder and contributing to uncomfortable summer conditions. Things like this greatly outweigh the basic thermodynamic analysis that you’d get if you looked at simple duct thermal losses due to being in the attic.
Even if it only made sense to add a couple inches of foam, you’d be amazed at how much cooler the attic is and thus how much less the losses would be for the air distribution system.
Hi again Ted, first thanks for all of the helpful information regarding making it a conditioned space. The pros seem to outweigh the cons for this at the moment.
One of your responses brought up another question, you said:
“Note too that once you’ve insulated in this way, the cellulose on the attic floor is extraneous and could even be harmful. Typically, it is recommended that you remove that insulation so that you don’t have a pocket of air (the attic space) between the roof and the ceiling of the living space. You really only want insulation in one location.”
and my question is this, don’t they typically insulate between the ceiling of the first floor and flooring of the second floor in a home or am I mistaken? I’m just thinking that logic would follow for second floor ceiling to attic floor.
If/when I do condition the space I will put some type of sub-flooring down to make it safe to walk on, at least where I can. That heat exchange unit in the attic is a beast and I don’t think I would be able to pick it up to put flooring under it. Plus the areas around the conduit, most of it is flex conduit so I should be able to work around that myself.
Typically, there’s only insulation in the spaces adjacent to the “outdoor conditions” – sometimes they may use insulation as sound deadening material between floors or in walls. That doesn’t cause a problem because the spaces on either side are heated/cooled the same. It’s a problem because moisture rises and if the attic is sealed AND cold, the moisture can lead to condensation/mold problems. This is one of the most important reasons why attics are usually ventilated.
If you remove the floor insulation, then the attic will get some of the warmth from the house. It still won’t be warm (I’m talking about winter), but it will at least get some warmth. With the insulation on the floor, very little heat will get up there so the attic will get quite cold, even if you insulate under the roof. Now, the moisture will be much more likely to condense. Sometimes, they will put a small heating vent into the attic space to keep the air moving and minimize the chance of condensation. People often object to this asking “why would I heat this space, isn’t that a big waste?” Basically, the anser is no – if you do a good job insulating under the roof, you’ll save so much more energy overall that the small amount of energy used to ensure the durability of your home is worth it.
Don’t worry about the subfloor areas around ducts and the blower. Small amounts of insulation left over will cause no problems because the heat moving through the uninsulated areas is vastly larger than the loss prevented by the insulation.
I recently painted my son’s bedroom and took the time to re-caulk around the windows and foam the outlets on the outside walls, both of which made a difference in that drafty room. The room has hydronic baseboard heat. Do you have any recommendations regarding caulking/spray foam around baseboard units? I was planning to caulk the bottoom of the baseboards when we get around to replacing the carpet in the room, but I was wondering if I’d get any advantage (or if there’s a problem) from putting a bead of low-expanding foam or caulk behind it.
There’s very often a big gap between the wall board (plaster or sheetrock) and the floor. Typically, this is included to allow expansion/contraction throughout the year though I’ve seen huge gaps and lots of drafty situations, so I personally sprayed foam in there in my house. The foam will compress with the expansion cycles. As you note – low-expansion foam is best to avoid putting too much pressure on the various components and risking cracking wall board.
As far as caulking the baseboard itself, I typically wouldn’t bother. Just fill in any obvious holes leading into the walls such as might have been drilled for wiring or pipes.
It doesn’t sound like Josh is headed this way, but just a word of warning when foaming around baseboards. I have hot water baseboard heat that was installed in an house with hybrid post&beam and stud-framed construction. There were huge holes bored through beams and plates to install the pipes and I thought, “Heck, why not foam these holes?” Well, the foam locked the pipes in place and the next time the heat came on and the 15′ long baseboards expanded, they accordioned in several places, as much as an inch. Two ended up springing leaks, one leak was inside a corner and went undetected for long enough for carpenter ants to find the wet old beam and set up a nest. All in all quite a repair challenge. So…don’t ever foam around hotwater baseboard pipes.
Yikes! That’s a lot of thermal expansion. I definitely hear the expansion noises in my baseboards when they come on and have observed the free-hanging supports, so that sounds like good advice – don’t do anything that would lock the parts in place without knowing how they’ll behave throughout the year and heating cycles.
Thanks for the insights!
We just read your article on heat pumps, and we have a question about the Carrier Greenspeed Infinity 20 Heat Pump. We live outside of Boston in a 3000 square foot old home. It has newer blown-in cellulose insulation and good storm windows. The current heating system is oil powered steam heat. It is a one-zone system and very expensive.
We are in need of air conditioning, and have come to the conclusion that if we install central air conditioning, it would be worth it to replace our heating system as well. That has led us to the Greenspeed Infinity 20 Heat Pump as an efficient and environmentally sound solution to heat and cool the house. We have found a good HVAC guy, I think, but he has never installed this system before and was unaware of it until just recently. He works a lot with Mitsubishi mini-split systems, which we have have also considered.
We went online and found a lot of very bad reviews for the Carrier Greenspeed system. We’re wondering what your thoughts are on this, and what you would recommend as the best solution for both our a/c and heating needs.
Thanks a lot!
Annie and Kevin
Unfortunately, I haven’t had any personal experience with the unit so I’ll have to look up the reviews and see what people have to say. One thing I can say is heat pumps, in general, often get bad raps due to improper installation and/or use. Unlike an oil or gas system, which keeps a relatively constant efficiency regardless of use, heat pumps revert to backup heat if you push them too hard, which can drive up operational cost 3-4x! Over the years, I’ve heard a lot of people griping about how expensive heat pumps are or how poorly they function due to these types of issues.
Regardless of what new system you install, you may want to keep the oil system in operation for backup heat. I did this in my own home and am very happy I kept the baseboard heat. I don’t use it often, but when the temperature drops into the teens or lower and the heat pumps are at the limit of their ability to satisfy my home’s heating needs, I turn on the baseboards and the house is comfortable again. If not for that, I’m sure I’d be griping about poor heat pump performance!
At the cost of the Greenspeed, you might very well install quite a few mini-splits around the house. Typical installed cost for a high quality mini-split is about $3,000-$4,000 per unit so you could get 4-6 for the price of the Greenspeed (at prices I’ve seen quoted). Since mini-splits allow room-to-room zoning, something you’re not likely to get with the Greenspeed, you can completely customize the heating/cooling as best suits your needs.
Another consideration of the mini-splits vs. a fresh central air system is running of ductwork. Retrofitting an older home that doesn’t have ductwork can open a Pandora’s box. It’s hard work and often, it’s nearly impossible to run ducts everywhere you want them due to space considerations. Try crawling around a dirty attic on your stomach while trying to do a neat job of installation… so what happens is that you get “out of sight, out of mind” syndrome. I.e., a really crappy installation job because the installer knows their work will never be inspected.
With mini-splits, you have none of these problems. You mount it on the wall, drilling a couple holes through the wall to run the refrigerant lines down to the outdoor unit. It’s in plain sight, so if installation is sloppy, you’ll probably see it immediately.
To summarize, if it were my home, I’d seriously consider installing a few mini-splits to augment the existing oil system, which I’d use as little as possible. In fact, this is exactly what I did do in my own home, even though I have central air and a geothermal system attached to it.
This is so helpful! Thanks a million.
Initially the HVAC guy was suggesting just this. And it sounds really good for just the reasons you say– that you can heat or cool just the kitchen if you’re in the kitchen, etc. The only down side I see is that to make it work for our whole house, we would need 3 compressors (I think that’s the name) outside the house– which seems like a lot of things coming out of the house. But this is the solution I was leaning towards, so it’s very reassuring to hear that you agree.
I’m glad that there seems to be a general agreement about this. I’m always a bit hesitant to give advice sight-unseen.
My brother also took this advice with his home and he’s been overjoyed with the results.
Talk to your HVAC contractor about “multi-headed” mini splits. Mitsubishi has a variety of units that use a single outdoor unit to drive several indoor blowers. They are less efficient than the best one to one mini splits but sometimes the tradeoff is worth it.
Good luck with the project! I hope that you’ll come back and let Mr know how it works out.
i have a crawlspace in my house, which i bought 3 years ago. am just wondering why the flooring is made of concrete in 2/3 of the area, and the rest is just a dirt floor covered with plastic. in the crawlspace, i have a furnace and water heater in addition to pipes hanging upon the joists. may i know the reason why there is a dirt floor?
Hmm, good question!
I’ve seen things like this before but don’t know why. Perhaps the house had undergone some renovations at some point, increasing the foundation’s footprint and they didn’t take the time to pour a slab in the rest.
If radon is an issue in your area, you’ll probably want to have it tested because dirt floors are notoriously porous to radon, and plastic laying on the dirt that isn’t very carefully sealed does little to stop the radon from entering the house.
Maybe someone else reading this can provide an explanation for the partial dirt floor.
Hi Ted. I was reading your article on rotten wood (http://tedsenergytips.com/rot/) and i may have a minor issue with some rotting wood on the bottom-left of my glass doors, behind the door mold. If i wanted to have somebody come in to inspect, who do i call? A general contractor? A window specialist? There must be a name for those who specialize in such detective work. Thanks. – Mason
Mason, a good general contractor should be able to help fix it. The trick is finding a good person to determine why it rotted in the first place.
Is that rot on the inside or outside? Outside is usually caused by wood in contact with the dirt or landscape mulch. if this is the case, then you should take out the mulch or dirt to give 3 to 6 inches of clearance between the wood and the ground. I would also recommend inspecting it during the rain to ensure that water isn’t piddling up. Draining properly around the house is really important.
Ted, it’s on the inside, the trim on the bottom-left of the double door. Last year i had an issue with the palladium window right above this door. The palladium window was leaking for about 8 months if the rain hit it just right. I suspect this window above the door was probably leaking down inside the wall.
Yesterday i was getting ready to paint when I found this soft spot on the molding on the bottom-left of the door. I noticed the paint looked slightly bubbled. It felt soft and when i picked at it, the wood underneath looks dark. I stick my finger into the sift wood on the molding at it’s bone dry (and it’s been raining the last couple of days).
I was just wondering who i can call in to assess the situation. I’ll do as you say and call in a general contractor. I can deal with internal walls. I don’t want to mess with external walls.
Ah, that’s a problem. I’ve seen a fair number of these types of issues – bad flashing/bad install of windows allowing water to leak down through the walls.
Unfortunately, this often turns into a “specialty” fix because almost no contractors have the training or equipment or diagnostic skills to track down the true problems. No offense to them, but it’s out of their realm of expertise. It’s kind of like going to the dentist when you’re having kidney pains.
What you really want to do is track down a “building science” person. This can be difficult but fortunately an increasing number of people are getting into this niche. If you’re friendly with contractors in the area, especially those who advertise “green building” skills and BPI (building performance institute) training, ask them who the best troubleshooter is in the area. You need someone with moisture meters – a non-invasive and a “probe” type that has 6″ long moisture probes. With these, they can stick the probes through your inside sheetrock after drilling small (1/4″ holes) for the probes. They’ll be able to track the moisture up through the wall to the approximate source. Even then, these can be a bear to find and will likely involve cutting out strips of sheetrock to see what’s going on inside the wall. But sheetrock is cheap, much cheaper than having to replace the wall studs when they’ve rotted out Trust me, you really want to get to the bottom of this. My first job diagnosing a problem of this sort resulted in learning that ALL of the flashing around a house was bad, leading to them having to rip off all the siding. When they did, they found wall rot all over the place! Yuck!
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