I bumped this back up to top of the list since it’s one of the most popular posts I’ve ever done. I also just had the misfortune of losing ALL THREE indoor units during a recent storm and power surge that killed appliances all around my development. Argh! However, they’re up and running again, good as new.
I love these heat pumps! There’s one in the bedroom, one in the basement “party room” and one in the large, living room that’s full of windows – a space that has been uncomfortable for years.
After installing these systems, I don’t know how we dealt without them before. The summer comfort is waaay better than ever. And in our basement room, I turned off the main heating system and used the Fujitsu exclusively all winter.
Keep in mind that this is one special little unit. There are many mini-split systems on the market that look like this, but most of them are barely half as efficient as this one. They’re just not in the same league.
Comments on performance
In the video, I make some bold comments comparing the efficiency of these units with those of a geothermal heat pump. Is this just idle speculation based upon paper specs? NO! I’ve made more measurements on actual HVAC systems than pretty much any HVAC technician out there. I have years of operational data for my own geothermal system and these Fujitsu heat pumps and I can definitively say that, on the whole, the Fujitsu units are as efficient as the geothermal. Why? a couple of reasons…
- A mini-split has no ducts and hence no duct losses
- Variable speed compressor and blower operation
- Smaller, more efficient blower
- Much less fluid to move around
Let’s look at each of these points in more detail.
A mini-split has no ducts and hence no duct losses
It takes energy to move air through ducts, much more than most people think. Depending upon the type of blower used, the blower in a typical, centrally ducted system uses 10%-20% as much as the compressor itself because it’s pushing air through hundreds of feet of ducts. The blower in the mini-split also uses energy, but much less because it isn’t having to send air all over the house – the air goes straight from the blower into your room.
This isn’t factored into the efficiency rating of a geothermal system, so right from the get-go, the geothermal loses about 10%-20% efficiency compared with the mini-split.
In addition, there are real duct losses. Every duct system I’ve seen has leaks. I spent a lot of time sealing my own system and there are still areas I can’t reach where I know there are leaks. And I’ve seen hundreds of duct systems and they all leak, some horribly. Studies have shown typical duct leaks may reach 30% on average. But let’s be generous and say that geothermal systems are much better than average and only lose 15% of their efficiency. That’s still 15% loss compared to the mini-split that has 0% duct losses.
So right off the bat, we’ve lost something like 25%-35% of the rated efficiency of the geothermal system compared with the Fujitsu mini-split.
Variable speed operation
Most modern HVAC systems have variable speed blowers, but almost none, except for mini-splits, have variable speed compressors, and that’s where you really need it. High end heat pumps/geothermals have two speed compressors, and that helps quite a bit to improve the system efficiency and evenness of heat/cooling delivery.
The inverter-drive mini-split heat pump has variable speed compressors and blowers, allowing it to carefully modulate the output. It’s not infinitely variable (based upon my measurements), but has a handful of speeds. What makes it really efficient is that when the weather is mild, it can really slow things down. So slow that you can’t even hear the system operating. Most of the time it operates in a middle zone. And only under extreme conditions does it have to ramp up to max.
Even geothermals with two stage compressors do not run very slowly/low power. The “low” stage is still about 2/3 of full output. This means in climates like mine where air conditioning is much less demanding than heating, even on the low speed, the air conditioning from a geothermal is less than optimal because the output is so cold that the system only runs for short periods and does a poor job at dehumidification. Some systems with humidity sensing thermostats and controllers do a much better job, but in general, in heating dominated climates, geothermals do a poor job at air conditioning. Trust me, I’ve lived with this for years.
The mini-split does an amazing job at air conditioning because it can turn down to such a low flow that it very effectively sucks the humidity out of the air during the summer. Even when you have those muggy, 75 degree days, the mini-split is still useful, while a regular central air conditioner is next to worthless.
Moving fluid
The geothermal people never talk about this when discussing efficiency, but it is a big deal. When you have thousands of feet of pipe in the ground, you need pumps to move fluid through those pipes. That takes a circulator pump that uses energy. So, even though the geothermal system is intrinsically more efficiently operating, the circulator is adding another 250-500 watts to the system’s power needs. So start with a compressor requiring 4,000 watts, add in 350 watts of circulator pump and 600 watts of blower and now the system is drawing about 5,000 watts. That’s 25% more energy required. To be fair, the blower in the mini split takes energy too, and you need several mini-splits to cover the area that you do with a single central air handler. But based on my measurements, the mini splits are using about half the energy to move the same air as the central system. So let’s say that overall, the geothermal is losing about 10% of it’s efficiency here compared with the mini-split.
There are other types of geothermal systems. Some use water wells and pumps instead of lots of tubing. But those well pumps are even more energy hungry. It’s very typical for those to draw anywhere from 500 watts to 1,500 watts. So, on average, those are no better.
Final thoughts on geothermals
I’m a realist. I am not condemning geothermal systems. In fact, in spite of the real issues I’ve raised here, they are still greatly preferred over furnaces and conventional heat pumps in some applications. There’s no other central heating system that works in so many climates and does it so efficiently. If I were building a large new home, I would most likely install a geothermal system.
But if I was building an addition, or supplementing the heating/air conditioning for an existing home, it’s a no brainer, I’d get the Fujitsu 12RLS. Not only in theory, but in practice, since I installed three in my own home. I definitely put my money where my mouth is.
The realities of air-source heat pumps
No matter how you slice it, the Fujitsu mini-split is an air-source heat pump. What that means is that, like other non-ground-source heat pumps, it extracts the heat from the air. So if it’s 10F outside, it’s trying to extract energy from that air. The basic physics of this is that the colder it is, the less energy there is to extract. There is also the reality of “defrost cycles” – times where the heat pump must run in reverse, actually putting out cold air in the house while it heats up the outside coils to melt ice. These two limitations are what prevent air-source heat pumps from being used in cold climates and what make ground source (geothermal) heat pumps so much more useful.
As noted, I live in eastern Pennsylvania. The climate here is moderate. Not too hot, not too cold. We get our stretches in the teens during January and February, and those times push the limits of air-source heat pumps. But for the most part, the temperatures are in the 20’s and 30’s during the winter – temperatures at which the air-source heat pumps work quite well. In fact, something like 80% of our winter temperature is above 30F.
But if you live in colder climates, you may find that conventional heat pumps aren’t for you. You might still use it for air conditioning and heating in mild weather, but when you have stretches of zero degree F temperatures, you’ll be hating heat pumps, so you absolutely need a ground source or fossil fuel system.
So choose wisely. I don’t want to be receiving hate mail from Minnesota or Upstate New York when you’re freezing in the dead of winter!
Follow-up: 1/6/2012
The U.S. Department of Energy, through their Building America Program, published this NREL Fujitsu12RLS report on the Fujitsu 12RLS and Mitsubishi FE12NA mini-split heat pumps. (Original source: http://www.nrel.gov/docs/fy11osti/52175.pdf)
Seeing the actual laboratory figures, I’m even more impressed than I was before. I encourage you to check out the report. In particular, the measurements show that the Fujitsu 12RLS is capable of putting out its rated 12,000 BTU/h all the way down to zero degrees F! From there, it gets better. At 30F, it puts out about 18,000 BTU/h.
You might be wondering, “what about the efficiency?” When the system is cranking away at full blast at zero degrees F, it has a COP of 2.0. This is pretty respectable because that’s still twice as much heat for your dollar as a conventional space heater. This increases to a COP of around 3 for most temperatures from around 15F to 30F. But, get this, when the system is purring away at mild temperatures from 35F up to 55F, the COP ranges from 5 to 6 (when running at low fan speed). This is absolutely phenomenal!
After reading this report, I’m much more optimistic about my recommendations for the unit in colder climates. If you can count on this type of performance down to zero degrees F, there’s little reason not to use the Fujitsu in most moderately cold climates we encounter in the U.S.
Ted's Energy Tips 
I need help! We just had a Fujitsu Halcyon mini-split heat/air pump installed in our guest house. The biggest surprise/complaint is that there is no temp gauge on the remote or wall unit?! Am I missing something? How do you know what the temp in the room is? And if I’m not missing something and that’s the way it is, what have others done to read the room temp in a way that isn’t unattractive. Second question: We live in NH and it’s the dead of winter. Last night it was 30 degrees and when I went in to start the heater I set it to max manual heat. It seemed to run for a few minutes, and then shut off for a few minutes, instead of a constant run. What’s that all about? Shouldn’t it blow hot air until I turn it off or switch it to auto? Thanks in advance for your opinions on these two comments!
You’re correct – for some reason, they only show the set point, not the current room temperature. It would make a lot of sense if they had a way to read current room temperature but….
Regarding runtime – it should run for more than a few minutes. All heat pumps have to use a “defrost cycle” to get rid of ice on the coils. During that time, the inside will actually run slowly and pump out some cold air, because they have to run in air conditioning mode. If the air is humid and cold, it has to run these cycles more often, which is probably what happened to you at 30F degrees. When it gets colder, there’s less humidity and less icing problems so it actually runs more.
So, depending on conditions, you’ll get hot cycling on and off for different amounts of time. But most of the time (90%?) it should be blowing good hot air. If not, there may be a problem.
I am estatic with the performance of my 12rls (1) mini-split. I use it, (only) for heating. It is very efficient and heats at lower temperatures, than I expected. I also bought the wired thermostat and interface connector.
I wish I could find an outdoor, anticipator and take advantage of TOU pricing. I believe, the Inverter technology, negates the value of my manual attempts (E.G raise (+2/4′) the temp, +/- 2 hours before the 7 am, price increase – shut off unit during (most) max-price time – before 7 pm, low price. I wasn’t ever uncomfortable, but it was seemingly a waste of time, using the best (external) daily, hourly, monitor, I could find. The price of my (daily) power was basically unchanged ! ( I will NOT pay $20-40), for a gismo to tell me that my ‘draw’ (?light?) is on!).
The monitor, said; using the 12rls, power consumption was 22% less for Dec, than last year – when the (electric) heat was set at the lowest setting, after Dec 10 – when I was away for a medical operation.
My TOU pricing, with electric heat is (‘b ass-ackward’) without using an outside anticpator/ manual (formula) input. I would question using any setback, (heating) settings with the Inverter motors(@constant prices. I would like to see measured results.
I also question the ‘installed price’. My installer was a family member. A very simple (knowledgeable) installation.
The updated models must be awesome!
JF: Does your wired “remote” include a thermostat that shows the rooms current temp, not what you’ve set the temp for? My wireless doesn’t, which I can understand!
Ted, I really appreciate your thoughts, I’m going to share them with my builder…I’m using a two stage unit (Am.standard platinum zm 4 ton-first floor is 2700sq ft) on the first floor, and I have a wood burning stove in the family room quad 7100….I’m told by my contractor that the insulation is flash and batt and this is supposed to be good….propane is expensive and the $4,200 tank installation doesn’t help….again, appreciate your thoughts and I enjoyed your youtube videos a great deal…Mike.
Glad to help. It sounds like you’re getting a premium system and have a place to get cozy with the wood stove.
If it’s that much for the tank install and propane is expensive where you are, there’s a good chance that a simple electric heat backup system would do the trick.
Best of luck!
ted builing a house in maryland avg lows 26 and 27 and 30 in winter months…should I go with a straigt heat pump central system or propane back up.
The answer isn’t cut-and-dried. It depends on a number of factors that include the size of the heat pump vs. the heating requirements of the house vs. the air conditioning requirements during the summer.
In your climate, you very likely have more heating demands than cooling, so the heat pump installer is going to want to size the heat pump so that it works optimally for air conditioning, maybe a little bit larger. Because of this, the heat pump will probably not satisfy all the heating demands during the winter. Therefore, they will prudently recommend the propane backup. This is for a standard single-stage heat pump.
However, if you get a two-stage or variable speed heat pump, they can often size it so that the second stage will satisfy your heating requirements on all but the coldest days and the first stage will run on the warmer days or during the summer for most of your air conditioning. This can work really well and would be my choice. However, these units are often substantially more expensive than single stage units. Most HVAC salespeople will talk you out of going with the two-stage unit, saying that the propane use will be so low that it’s not worth the premium of the two-stage unit. You have to weigh the costs based on their projections of the amount of time that the system will run on propane vs. heat pump alone.
Where I am, propane can be very expensive, so I’m more of a proponent of using a two stage or variable speed heat pump, sized to satisfy my heating needs, then supplementing that with cheap (to install) electric backup heat. If sized properly, the electric backup will almost never run. However, if sized too small, it can cost a fortune to run because the electric backup will run too much. I’ve seen this more times than not, and wouldn’t trust most HVAC installers to do the job properly.
Another factor that comes into play is how tight and well insulated your house is. If you’re doing it really well, like using spray foam, then you’ll have much better luck with a heat pump, which doesn’t work well if the house is leaky or not insulated very well. I’ve seen plenty of “code built” homes that fail with heat pumps because they really aren’t very tight.
I know this can be confusing, but this is one of those things that often works on paper but requires the builder and HVAC contractor to do their jobs well. I wouldn’t want you to be disappointed with the results.
The safest solution is to install the propane backup system. That provides plenty of excess capacity for heating so you’ll be cozy and warm on the coldest nights.
The least expensive solution (to install and operate) is an electric backup system combined with a properly sized two-stage (or multi-speed) heat pump. In a new construction, it’s possible to make this work really well. But like I said, your builder and contractors have to do things right or you’ll end up with shockingly high electric bills.
Ted , thanks for all your post. I enjoy reading everyone’s input on the Fujitsu Systems. My wife and I have decided to go with a Fujitsu system for our ranch home. We will be having 2 – 9 RLF’s for the bedrooms and 1 12 RLF for the living room and dinning room. We live in central Indiana and currently use baseboard heating. I would like to know if a portable generator would work with a Fujitsu system. I have never used a portable generator here at the house but we do seem to have a few power outages every winter and some in the summer. I’m not wanting to power the whole house just the heating and cooling and essentials lights, well, frig.I also plan on using a transfer box with the generator.
Thanks Ted for all your expert advice.
Byron
You’re welcome – it’s my pleasure to be able to share what I’ve learned with others.
Regarding using the Fujitsu units with generators – keep in mind that you need a good 240v source. I’m not sure about how good the waveform of the generator needs to be in order to drive the Fujitsu. Some of these generators have very poor voltage stabilization that can damage some electrical devices. I’d strongly recommend talking with both somebody from Fujitsu as well as the generator manufacturer (which may be challenging) to determine the requirements – you wouldn’t want to fry any electronics or the Fujitsu units!
Note that you’re not likely to get useful or accurate information from the sales reps. You really need to talk to the technical support people at the manufacturers.
A couple tips – some generators are listed as “computer safe” or “true sine wave” – if they say that, they’re much more likely to be safe for use with the Fujitsu. Then you just need to have enough juice. Fortunately the Fujitsu units gently start the compressor and fan units, so they don’t “slam” the generator with a sudden full load. You just want to size the generator with enough capacity for your worst case usage plus a bit of extra so you don’t overload it.
That should get you started. Feel free to drop another question if you need any clarification.
Hello ,Ted
I took your advice and contacted Fujitsu General and thought I would leave their response for all that might be or are already using a portable generator.
We don’t recommend unit to be connected to a generator. While a generator does put out voltage , it seems like the hertz cycles are not suitable for our control boards and this can cause problems with the operation of your fujitsu unit.
Eric Sarrow
Senior HVAC Technician
Fujitsu General America Inc.
353 Rt 46 West
Fairfield, NJ
973-575-0381 *2
866-952-8324 *2 (outside of NJ)
FAX-973-836-0449
EMAIL-esarrow@fujitsugeneral.com
Thanks so much for sharing. This could save others a lot of problems and potential expensive repairs!
Ted, thanks for taking the time to reply to my questions. Now as Peter Falk used to say just a couple of things more. Can you direct me to a good site with a calculator as you suggested where I can try to get a comparison between oil heating and heating with a heat pump. As you know there are so many variables it will be quite a task, heater efficency, COP of heat pump, time of use electricity rates and of course outside temps just to mention a few.
Also have you seen the specs for the new RLS2 line from Fujitsu? There was an earlier post on this. According to my distributer’s site here in Canada the HSPF is the same @12 but I am wondering how much more efficent they are at low temps? Just my luck that they would come out with a better unit a few months after I installed mine. Well I guess depending on the price of oil I may be in the market for another one? Please have a look at the chart on the bottom of this page for comparison between the RLS and RLS2 and please tell me what it means.
best regards
Jack Leonard
Click to access 0Fujitsu_9_12_15_RLS2_eng_02_12.pdf
I’ll have to dig around. I’ve found some cost calculators, but they’re primitive, without the options, like time of use. But it’s a start. You need to go to dedicated software that uses average hourly temperature data and runs full simulations to get the details you want for better accuracy.
http://nepacrossroads.com/fuel-comparison-calculator.php
This is a nice comparison calculator:
http://www.energyexperts.org/CalculatorsTools/HeatingCostCalculator.aspx
And here’s a spreadsheet for doing the calculations that also has a table for derating HSPF based on climate zones
http://www.eia.gov/neic/experts/heatcalc.xls
As for the RLS2, I checked out the specs and it’s marginally better but not enough to give me buyer’s remorse. The charts on that PDF you linked to does look like they’ve really optimized for cold temperatures, so maybe I have to rethink that! For colder temperatures, the new units look substantially better. For example, at 5 degrees F (=-15C) the new “12” unit can put out about 13,000 BTUs/hr while the old one was good for about 10,000. That’s significant.
Ted, thanks for reposting your video on the mini split heat pumps, as you know from my earlier posts I installed a 12RLS in mid Dec/11 and have been quite happy with it here in eastern Ontario, Canada. But I haven’t seen the big dollar savings that I had anticipated. I think the unit is going to be most effective in the so called shoulder season, March and April and Oct, Nov and December and probably a full year of use will tell a better story. One thing that complicates the picture is my house layout. I installed the heat pump in my kitchen and the dining room is directly adjacent. My wife says the dining room has never been warmer. Also on the same level (lowest) is the laundry and bathroom. The problem is this, a wide hallway from this level opens to a family room which is 5 steps higher and I think a lot of heat is migrating to this room and then up a second stair to the three bedrooms directly above the lowest level. I have a Toyotomi oil heater in the family room. Another piece of incredible Japanese technology by the way. This oil heater is fully 90% efficent and puts out about 23K btu’s on high and is direct vented. But you know what is happening to oil prices these days.
Finally my questions. Should I try to block the heat which I believe is moving up to the family room. I say that because the oil heater has used only half a tank of oil and by this time would normally be down to less that a quarter tank (900 litres) Yes that’s right the Toyotomi never uses a full tank of oil in a season. I could easily block air flow with a simple curtain.
Second, is there any way to do a comparison between heating with oil and heating with a heat pump? this is complicated in my area because my utility uses TOU pricing.
Thanks Ted for any advice or insight you can give me
best regards
Jack Leonard
Hi Jack, good to hear from you again! This is timely given the other discussion with Ken who’s planning on doing an installation.
The issues you’re having probably does have to do with convection loops as you noted – hot air rising up and the colder air falling down, forcing the system to work extra hard and effectively heat a much larger area.
I had a client who was heating his home with a wood stove in the living room but was losing too much heat to the upstairs which was largely vacant. All he did was set up a “dam” at the ceiling to keep the warm air from going up stairs and it worked very effectively. Cold air still dropped down the stairs, but much less.
If you’re having problems imagining that, think of hot air like water and turn the house upside down. If the heater is pumping out water, it would flow down, along the floor, and you could stop it from flowing further down by putting up relatively small dam. With air, you need a relatively larger dam, maybe 1 foot, but you probably don’t have to block out the entire opening. Your idea of a heavy curtain works very well also and allows you to come up with a more aesthetically pleasing solution.
You can do a comparison but it is particularly difficult with an inverter system like the Fujitsu so you have to go by published figures for the COP of the unit. There are a variety of on-line calculators where you can plug in your utility rates, COP, etc. and it will show you the comparative costs. That should get you ballpark figures. In colder temperatures, the heat pump COP is dropping down around 2, so, as you say, the units will be vastly better in shoulder months where the system isn’t running all-out and the COP can be upwards of 4.
Hope it helps!
Hi Ted, a couple of questions about your experience.
You mentioned you have a unit in the basement, a large living space and in the bedroom. Do you have other bedrooms in the home and if so, are the units able to maintain comfortable temps, even without having their own unit in the room? I have two bedrooms that seem to have higher heat loss/gain compared to the rest of the home and based on a room-by-room Manual J, one unit (even the 9RLS) would be oversized for both rooms (total BTU/H loss at design conditions is ~5600 BTU/H for both rooms). However, I think airflow between the rooms would be a challenge with only one unit. I’m considering placing a single 12RLS2 in the Great room (adjacent to the hallway that connects the two bedrooms) but am still concerned the temperature will not move into those rooms adequately. They are tight (measured by blower-door) and insulated (R-13 walls, R-60 attic), but walls are not super-insulated.
Secondly, you mentioned in your original post that optimal efficiency is with the blower speed on low. Would you mind elaborating? Are you referring to comfort, efficiency, or another issue? If optimal efficiency is on the “low” blower setting, I would consider putting a 9RLS in each bedroom but obviously, that would require a significantly higher initial cost and still be 6x oversized, even at design conditions. I plan on doing the install myself (I’ve already installed one in our bonus room and am now taking HVAC courses at the local college to get a better handle on such things) so installation costs for needing to add the second unit would be minimal.
If I install myself, even one unit in each of those two rooms (and 2 other units) would be lower than the quote I received on the Carrier GreenSpeed, even after including the price of classes at the local college so I am really considering this option.
I am just south of St. Louis, MO. If you need additional info, I would be happy to provide and appreciate the help. Thanks
Hi Ken,
My home has several heating systems: Three mini-split heat pumps, a central forced air ground source heat pump, and baseboard convectors heated by an oil fired boiler. Depending upon the weather, I’ll use one or more of these.
Your concerns are real – mini-splits in conventional homes (i.e. not tight, super-insulated homes) are going to really fall short for rooms that aren’t openly connected to the space in which they’re located. What I do during moderately cool weather is just run the system in my LR and let it passively heat the rest of my home. Sometimes I’ll turn on the blower on the central system to help distribute heated air throughout the house. In your situation, you might be able to get by if you add “jumper” ducts between the rooms and circulator fans. That could do the trick but the room with the mini-split will still certainly be warmer than the other. I haven’t tried this myself, but I think it’s a valid, albeit atypical, approach. The trick with these custom approaches is that, while they may be fine for you, if you sell the house, either the inspector will flag it or the new owner won’t know how to use it optimally. So I always recommend that people trying things like this still have a conventional central heating system for their home. At the very least, I’d install electric baseboards in each room (as horrible as that is for efficiency), to take up the slack and in very cold weather where you’re pushing the limits of the system. That’s no different than the back-up heating coils in central systems, so it’s not that bad 🙂
As for efficiency, the idea is that at lower speeds, the size of the coils is larger relative to the capacity. This provides increasingly higher transfer efficiency. In addition, it requires relatively less energy to move the air since energy to move air increases non-linearly the more CFM’s you’re trying to move.
My strong recommendation would be to bite the bullet and “do it right” with one unit in each heavily used room and not try anything too creative. My master BR is probably like your room, in that the walls and ceilings are well insulated and tight so the actual loads are quite low compared to the system’s capacity. Since the system can purr along silently and keep the room comfortable while we sleep, that’s ok. Sometimes, I’ll let it run during the day even though it’s not occupied, so that the conditioned air can help keep the overall house conditioned. This is especially true in the summer when it’s muggy out.
Your climate is very similar to mine, so I’d expect your results to be similar.
Thanks Ted, I had considered the “jumper ducts” but didn’t want to get overly creative and I still wasn’t sure how effective it would be. I am willing to put a unit in each bedroom, keep it on low blower speed and play with the settings. At least then I should never have to worry about our little ones being uncomfortable in there as there should be plenty of heating/cooling. Currently, we have a Carrier (base model) heat pump, which was (in my opinion) incompetently installed and lead to major comfort issues (including high humidity in the summer). As we continue to take energy-efficiency measures in our home, the unit becomes more oversized. Couple that with undersized supply and return trunks and we have a noisy, uncomfortable system. On the other hand, once we finish our air-sealing, additional insulating and other measures, I’ll install the Fujitsu’s and uninstall our current heat pump. The plan is to replace it with smaller AHU with electric heat strips (instead of, but along the same lines of the baseboard that you mentioned) for the extremely cold weather. Although we rarely see temps down to 0, and even then I think these units will be oversized enough to handle the loads.
Back to the point though, I needed to hear a credible source (especially one with user experience) say it is OK to oversize the units for small rooms, just let them purr along and not be afraid to turn them off when they’re not needed. Thanks for that.
And thanks for the description on the blower speed, it helps make sense of the results I was seeing in the NREL report you linked to.
Glad to be of assistance. It really looks like you’re doing your homework. If you combine the mini-splits with a replaced central air distribution with heat strips, you’ll probably be in good shape. Those Fujitsu’s have been a godsend during the summer for humidity removal! My geothermal is only 4-tons, but it air conditions so much that humidity removal was abysmal. Now I use the Fujitsu’s all summer and only run the geothermal system when it’s unbearably hot out.
To your point on oversizing – that inverter drive is miraculous, so you’re never really oversized in the conventional sense. I just see it as giving you headroom for all conditions up to the most extreme. Plus, you’ll appreciate having the extra capacity during the winter when the heat pump side of things puts out less and less heat. To me, the fact that these little units can ramp up and down to handle a range of loads puts them miles ahead of conventional central systems – air source or geothermal. The geo guys will be annoyed at this statement, but I stand by it. If I were designing a home from scratch and had the choice of a single big ground source heat pump, (even with two speed compressor), versus a bunch of these Fujitsu’s, I’d go with the Fujitsu. You simply can’t beat the room-by-room zoning capability combined with the inverter drive.
Please let us know how it all works out for you. Everybody learns from discussions and “experiments” like this and there’s no more convincing argument than when you’re actually living with the system.
There is a new model called the [9/12/15]RLS2. You can find them on Fujitsu’s website. Specs for the 12 and 15 have not changed too much but they have improved slightly. The 9RLS2 now has a SEER rating of 27.2. They are advertised to operate to bellow -5F and considering the reports on how well the [9/12]RLS have performed in below freezing temps these should be even better.
Thanks for the update. They’ve also upped the warranty.
Also, here’s an entire research report on the Fujitsu 12RLS.
http://www.nrel.gov/docs/fy11osti/52175.pdf
I’ve recently learned about Marc Rosenbaum’s excellent blog. He’s reported on his experience with the Fujitsu as well
http://blog.energysmiths.com/2011/12/a-year-with-a-minisplit-heat-pump.html
Be sure to check out the comments as well. Good stuff in there.
Thanks Ted,
We live in Weed California – close to Yreka. When we moved in we got Pacific Power to come for an energy audit and have fixed most of the problems i.e., new windows, insulation and heavy duty caulking.
I appreciate your help, especially about the wiring issue, and you may be right about settling on a high end central heat pump. But this is another minefield because they all seem to get mixed reviews and I hate to depend on the choice of my contractor. Have you heard a good word about any particular brand? A reliable unit plus an improved, enlarged duct system will at least decrease my electric bill and maybe next year we’ll have enough money for solar power.
Keep up the good work! I’ll continue to read you cause I enjoy your site tremendously
Tricia
Looks like a really beautiful location! I checked the climate data and the overall heating requirements are very similar to mine out here in Eastern Pennsylvania. So my cautions stand – I would definitely want some backup heat source. If you wanted to do it “on the cheap”, you could always use some of those inexpensive oil-filled 120v electric radiators to take the edge off on those cold nights. I’m not sure what the code officials are like out there. In some areas they would insist on having hard-wired backup heat for the heat pumps, so you’ll have determine that for yourself. One of these can put out about 5000 BTUs. In combination with the heat pump, you should make it through most nights. At under $100 per room and no wiring needed (as long as your house wiring is up to snuff), you’d be in good shape.
Sounds like you’ve been doing your homework and done the important work to your home, so you’re in much better shape than most.
As for brands, I’ve heard good and bad things about all the major brands – Carrier, Bryant, Trane, etc. I actually had some work done recently because a huge power surge knocked out all three of my Fujitsu units. I got to talking about heat pumps with my repair guy who was raving about his Carrier Infinity. And indeed, if you look at the specs, they’re outstanding. The trick is usually the installer – they make all the difference. If you’re lucky, you’ll have someone you can trust.
Good luck with everything!
-Ted
Dear Ted-san,
It’s wonderful to have you as a resource. My husband and I retired and bought an older home in rural northern California with a 20 yr old Coleman heat pump that is slowly dying. Other than space heaters it is our only source of heat in an all-electric home.
Our home is 3200 sqft with three levels – top level is master bedroom/bath about 240 sq ft so the 9 RLS is a no brainer. The middle, most used area, is open concept with vaulted ceilings (kitchen, dining, living room) about 480 sqft along with (2) 12×10 bedrooms. Finally, the lower level has a 350 sqft open room and (2) 10×10 bedrooms.
As retirees, we use all three levels but only the master bedroom, however, I need to be able to heat the other 4 bedrooms for short periods when the kids and grandkids visit. Plus we may need to utilize these bedrooms if children return long-term or for any future in-home caretakers.
My husband wants to change over to the Fujitsu and keep the Coleman for backup in the rooms not fitted with mini-splits. But then what do we do for those bedrooms when it finally dies? I wonder if the Fujitsu 2-4 room Halcyon inverters on the two lower levels are the way to go or do what you have with individual 9-12 RLS?
I am concerned about the wiring issue and if the 220 necessary for these systems will mean having to re-wire much of the house. The box is on the other side of the house from the main living areas. Other issues – I cannot sleep with the noise of our current heat pump (yes it is old) and do not like to have air blowing on me all the time. And what if we lose the remotes?
But a new HVAC central heat pump system with potential duct leaks, rodent problems, reliability issues and the costs (both installation and monthly bills) make me wary. We plan to spend about 12-15K for either option but because we are on a pension we really need to make the smart choice.
I want to be warm and have peace of mind that our decision will be a wise one, and I trust your valuable insight …please help.
Tricia Sova
I’m so glad to help.
First, I should say that it’s impossible for me to give definitive answers without seeing and evaluating your home. Standard disclaimer 🙂 but I’ll do my best to give you information so you can come to your own conclusions.
A question – what city are you in? I can look up the climate data to get an idea of what you’re dealing with. In particular, I’ll be looking to see how much time you get that’s below freezing. Even these heat pumps can struggle when you have very cold weather. Because of that, and since the 9RLS and 12RLS units are basically the same price, I recommend going with the larger systems. With heat pumps, you usually don’t want to do that, but these units are variable speed, so the larger unit gives you exceptional performance and more capacity for those cold spells.
If you do get extended periods of sub-freezing temperatures, you’re going to want some supplemental heat. With a central heat pump, usually that means heat strips in the main unit. For units like the mini-splits, the most cost effective is baseboard electric heaters. While inefficient in comparison with the heat pump, they’re very inexpensive to install and they give you peace of mind that you won’t freeze if you have a problem with one of the units or if it gets so cold that they’re unable to keep up with the heating needs. You could also install those in the extra rooms if they’ll only be used intermittently. I wouldn’t want to heat with straight electric baseboards for months at a time, but for short visits, it’ll do the trick.
Wiring is definitely a concern. I had to play some games in my house in order to get 240v where needed. Depending on the construction of your home, this could be easy or it could be a nightmare. Best to consult an electrician before you dive too deeply into this. It may turn out that you just have to get an efficient new central heat pump. Realistically, for a home of your size with a number of different spaces to heat/cool, you’d probably be best off getting a high end central heat pump. These mini-splits are great if you’re installing just a couple, but the installation costs really add up if you start needing too many more.
Since you’re in California, you may want to get a local energy consultant to walk you through this and check out your home for other things that could be improved, like insulation and air leaks. Especially with heat pumps, spending about $500 for a quality evaluation is well worth it. I’m not sure if CA give rebates for energy audits, but it’s worth looking into. A word of warning – just like most professionals, you have to do your research. In the last few years, a lot of people are calling themselves “energy auditors” that really don’t have the knowledge to do the job. You want someone who has been doing this since before it became the “in thing” to be green. I’d look for someone who has been working for at least 5-6 years and has a lot of evaluations under their belt.
Hope this helps.
-Ted
Hi Ted, I live in Southern Maine. We are building a new “retirement” home. I have looked at geothermal systems and the cost is very high with a very long payback period-way beyond my life expectancy. My friend and very reputable HVAC contractor today showed me a brochure on the new Carrier Infinity 20 high efficiency heat pump system with a propane furnace as a backup fully ducted. As another choice we could install any combination of Fujitsu mini split units. In any case we are installing a 25,000 BTU propane fireplace on one end of the open concept home that can amply serve as backup for the home when things get really cold if we go with the Fujitsu system and we could always pop in some electric baseboard heat in the closed off bedrooms. (We will have a standby generator that will be able to serve either of these systems). We only go below 10 degrees about 10-15 nights/year and not often during the day. Only a handful of sub zero nights/yr. We plan on foam insulation in the walls (R-35, average R-25 once studs/windows are included) and foam/blown in cellulose in the attic for R-60+). What are your comments regarding which way I should go? Like the idea of separate controlled zones and low cost of the Fujitsu but also like the comfort and built in backup of the Carrier. A/C is a no-brainer with either system in our climate. A bit torn. Will use instantaneous propane Hot H2O (probably Bosch condensing unit). Will have electric radiant bath floor in master bath. Also have looked at the lowering cost of PV panels (Maine is an electric grid buy back state) to lessen the electric bill-but currently makes no real sense.
Hi Bob,
It sounds like you’re building a wonderful home in Maine, congratulations! It’s not often that people really think about these issues.
Since you’re super-insulating your home, you’ve made the job of the HVAC system much easier. With good foam insulation and high R-value, the heat loss from each room will be way less, so the home will naturally be much more comfortable than a conventionally built one, regardless of the HVAC.
From a cost perspective, the installed cost of the Fujitsu is going to be $2500-$3000 per unit, so it adds up quickly. But, as you note, having one unit in each area allows zoning that you’ll never get with a central system.
If I were in your shoes, I would probably go with the Carrier central HVAC with propane backup for a few reasons.
– Even though it’s not a super cold climate, it’s cold enough that any heat pump will struggle. Especially when you’re in the 25-35F temperature range, there will be a lot of defrost cycles. When they hit, you end up with very cold air coming off the indoor unit for a few minutes. With the central system/propane, it will typically shut down the heat pump below 35F and just run off propane, so the comfort level will be better. My wife is sensitive to those cold drafts, so I typically run some other heat when it gets cold to avoid annoying her.
– The convenience of a single thermostat shouldn’t be underestimated.
On the other hand, the efficiency of the Fujitsu is still about 25% higher than the Carrier for heating. If you go with the backup systems (some electric baseboard and the propane fireplace), you’re in good shape regardless of what you do. But again, that’s even more manual setting that you need to do. Think about having to manually go around the house, setting maybe 6-8 different thermostats in order to keep things comfortable with that setup. My guess is that at first, it would seem pretty handy but after a while, you’d be wondering why you didn’t go with the central system.
Good luck with the house. I hope you’ll post an update when you’re done and have lived in it for a while.
Hello Ted, thanks for posting the info on the 12RLS. Why did you decide to use a single indoor unit system which I believe the 12RLS is as opposed to a system with I believe up to for indoor units? I see you have two or more 12’s what is your reason for that?
regards and thanks
Jack
Jack,
I looked at the specs of all the multi-head units and none came close for efficiency. The 9 and 12RLS have SEER ratings of 26 and 25 respectively, which is about the same or better than geothermal heat pumps. In other words – spectacular!
The multi-headed units are good, but most are in the 14-16 SEER range so I was willing to go to the super-efficient individual units.
Thanks Ted, I should explain, I live in Canada about 40 miles north of Ogdensburg NY and I know it gets a lot colder here than what you experience. My son once attended the Little League camp at Williamsport PA. and I could tell on my visit there that the summer temps were quite a bit higher than we get although with the changing climate you never know anymore and we do get periods of four or five days of plus 90’s F temps and sometimes higher. My main concern is heating and I notice that the 12RLS has the highest HSPF of 12 that I can find in any brand. Again winter temps can be severe here but seem to be moderating over the last several years. I don’t have temp statistics handy but I do know of a couple of people using the 12RLS and having good heating success. I guess my plan now is to install one 12RLS in the main part of my house. I will evaluate it and decide what to do later on. I would have been ideal to install a unit with two indoor units but the HSPF seems a lot lower on those. I have looked at Mitsubishi and their ratings are no better and probably not as good.
Your comments please
Jack Leonard
Colder weather definitely challenges heat pumps. I took the same approach as you – try one and see how it works and expand. As you say, the HSPF is also super on these units.
I use my house as a test case for different systems, so I’ve got oil fired baseboard hot water and a geothermal. The oil fired system gets used in cold weather to supplement the heat pump. Once I got the Fujitsus, I barely use the geothermals for cooling, but still use them for heating.
I hope they work out for you. You’ll definitely need extra capacity in the cold climate because heating output drops considerably in the cold. I hope you’ve got good insulation!
Ted,
I thoroughly enjoyed your article & video. I recently installed 3 single fujistsu units and a double (single compressor and 2 air handlers). I went this route for many reasons. 1) I live in central Pa (North of York), which has a reasonable climate. 2) I have an older home and installing duct work would really destroy the look of the space.3) I’ve really grown to hate those noisy window air conditioners, 4) I’m dislilking the cost and poor efficiency of steam heat. and 5) When I priced a new steam boiler and air conditioning units against the efficiencies, I was totally not impressed. But once I found out that the fujitsu units are also heating units and saw the SEERs(24-26) and heating efficiencies, I was sold. The units went in in July of this year (2011). My electric bill to keep the house quite cool increased only $20/month. When I had the window units, my electric bill increased $35-40 /month and that was to cool only 3 rooms. Now I cool the whole house for almost half the cost!! I’ve had the opportunity to test the heating side of these units and they were great. But I do have two complaints about these units: 1) they are so quiet that I periodically need to check if they are actually running!, and 2) it would be great if I could control all the units from my computer instead of having to go and manually set each one (albeit via a remote). Other than that, this was the best money I ever spent. Although my steam boiler is old, it still works and I;m keeping it as is for back up heat – just in case. These Fujitsu’s are rated to operate down at high efficiency down to 17 degrees and keeping working down to 4 degrees (although at lower efficiency).
I really enjoy the constant temperature – no ramping up at max to cool / heat and then shutting down, then ramping up, etc. These just keeping on keeping the temp constant with their vaiiable speed!!!
Thanks for your feedback and comments! It’s great that others are having good luck with these units. I think they’re perfect for air conditioning in our moderate climates with lots of humidity.
During the cold winter days, you’ll certainly have to run your steam heat, but you can still use the mini-splits to pump some high-efficiency heat into your home, so that should reduce your heating bill as well.
I’d love to have a wireless connection to the units. Using a standard IR remote seems so 1990’s!
Cheers!
-Ted
Ted-san –
Today is 15th May 2011. Please prepare for extensive message –
Hello. My name is Randy. Watched with very great interest the EnergyGeek episode showing the Fujitsu 12rls Mini-Split unit.
Summary and Thumbnail :
I have an opportunity to obtain assistance in upgrading my home A/C, but that assistance must demonstrate a ‘real’ energy efficiency improvement .
Overall, wondered if a replacement rooftop central A/C – and its SEER – to supplant my current worn HVAC system could compete favorably against the Fujitsu unit you reviewed; and would that (the Rooftop A/C) Rate as a ‘real’ energy efficiency improvement? Or should I simply go with a high SEER Mini-Split? I’d also like to combine an Evaporative Cooler with either of the A/C replacements owing to the climate I live in.
Background Details :
In your summary comments you mention the best use of Ductless Mini-Splits would be in homes with new additions and/or areas without ducting. I’m hoping to cool and heat our entire home – breaking the home into perhaps four or five zones – by means of this brand/model or an installation quite like this; something which boasts a notably high SEER rating – perhaps even by means of my own mix of Mini-Split brands and styles. (I’ll break down structural details with location profile as an End Note). This is all due to our prohibitively high electric bills which we experience six to eight months each year (here in the Phoenix, AZ metro area). We also discovered that our electric bills are slightly higher than some other homes in our immediate neighborhood. I worry, however, if the electrical load of two or more ‘Outdoor Units’ would surpass the power drain caused by my current old, inefficient rooftop HVAC unit, and “fix” the situation in a way that’s as bad or worse than the standing problem.
As the second owner, we’re finding that the structure was built with ‘Slap Together’ construction by a builder who used low-grade parts, and employed the most typical low-rent solutions to barely threshold the energy demands of an earlier era. Because it’s already ducted for an old-school type of HVAC system, what do you think are the upsides and the downsides of the conversion I’m considering? (All but the most mild home mods, and definitely nearly all the invasive structural modifications are out of the question).
Here’s the one major approach I’m weighing: If we chose to go with a Mini-Split Ductless would it be “doable” – and would it be wise – to route the Line-sets up to and snake them through the existing AC ducting to minimize impact on interior structure? Having absorbed some of the information on your website, I’m becoming keenly aware of energy losses because of ducting inefficiencies. And how would a Mini-Split work for heating, then, since with the current HVAC we now merely adjust the thermostat. This bit of co-opting the in-place ducting would also locate the Air Handlers close to or directly at the sites of the existing vents. Of course, there would be more existing Vents by count than I can envision there being Air Handlers – it wouldn’t be a 1:1, point-for-point replacement.
I usually reject what appears to be marketing-emphasized ‘Helpers’ on a manufacturer’s website – But I did go to Fujitsu’s online presence and used their generalized energy load calculator where its results suggested our HVAC SEER is likely approximately 10. I’m guessing, knowing more about our precise location in the Phoenix-area (the so-called Valley of the Sun), that the SEER is closer to 8. We had A/C professionals out to the house just a couple weeks ago who said they thought certain that if a Load Audit was conducted, it would NOT register a SEER above 9. They recommend system replacement ( moreover, in the six years we’ve owned this property, we’ve repaired the system twice previously with two different A/C companies each of whom suggesting the same thing, citing wear and age. These started out being just standard springtime maintenance/”tune-up” visits ). We’ve not yet had a formal thermal load audit.
I also wanted to augment all of this with an in-window, single-point whole-house Evaporative Cooler (this one here – http://bonaire-usa.com/en/products/bwc.aspx ) . The Ductless Mini-Split heat pump coupled with the Evaporative Cooler would form our new HVAC system – as I foresee things. And I say so being completely unschooled where such things are concerned; yet I haven’t been idle. I’ve spent a fair amount of time online attempting to educate myself with the background realities and impacts, which includes combing through your website and your YouTube Channel. I’m not arrogant; I’m obviously not qualified to evaluate this myself. I don’t mind being corrected if I’m wrong – I’m fundamentally suspicious and reject sales-related crap, and desire balance and truth relayed to me accurately.
Would like your thoughts on whether to spend the roughly $7500.00 on holding steady with the in-place ducting and simply purchasing a respectable drop-in replacement Roof-mounted Central Air Conditioner – or obtain the best available Mini-Split Ductless system … each of which I would combine with an Evaporative Cooler, hopefully the whole thing coming at a persuasive cost.
It would be greatly appreciated if you could address this.
I’m at : scobeaux1@gmail.com
End Note (Specifications) :
Locale and Climate –
We live in the suburban desert : Peoria AZ area with demonstrated temperature extremes of 21 F to 120 F degrees. Late Spring to early Fall: typical daytime temperature is between 90 to 115 degrees. Overnights range between 40-ish and the high 70’s. Phoenix area Summers: the temperatures drop only very slightly overnight. During triple-digit heat it is common to have overnights at a lower triple-digit temp or high 90’s. We have what we call a ‘Monsoon’ for about a six week period occurring, roughly, between last week of June and the beginning of September at the latest – start and end times vary. Therefore, we have two seasons of rain; second of which is Fall/Winter. Monsoon humidity elevates and peaks at 55 to 60 percent; it is higher than normal, but discontinuous. Typical Phoenix humidity at all other times is 9 to 18 percent.
Structure and Property –
Home is 1950 sq ft two-story, three bedroom. Rectangle footprint on the property. It was built in 1995 (we purchased in September 2004) and the Central A/C unit is roof mounted – to date, still all original equipment. One of three repairs made since we’ve owned this dwelling has been a rebuild, but no new A/C installed in that period. We have natural gas heating and cooking. Ground and upper floors are nearly identical square footage.
Ground floor is relatively open ( few walls and no doors – not fully enclosed. Powder Room adjacent to kitchen has the only door). Backing up to the Powder Room is a vaulted great room (16 feet high at peak) and its cubic space is connected to a staircase leading to an open second floor aisle (making one enormous continuous, yet odd-shaped area comprised of a huge amount of cubic feet).
Second floor has three bedrooms and a separate bath, all enclosed by doors, of course, with that open atrium mentioned before as access to the second-story rooms. From the face of the closed upstairs doors to the ground floor great room – together form one profound, meandering openness.
Have a front attached two-car garage {which we want to convert to a home office down the road}.
The short side of the rectangle of the home footprint faces East. Have three 57×35” windows and one 57×70” window having southern exposure; and two 57×70” windows along with a small two-pane slider (74×78”) having western exposure – One north-facing 57×35” window (100% in shade). Three smallish windows facing east – two upstairs, one downstairs. One 57×35” window upstairs facing west. All windows are double-pane, metal framed. The windows noted are fully exposed to light without awning or tree shade. The Slider is under a small patio cover built from the west-facing exterior wall out eight feet by thirteen wide.
I know this is quite detailed, but thought this level of detail would paint the correct picture for you.
What a great question!
First, the most basic – the efficiency of the Fujitsu mini-split will greatly surpass the efficiency of any central heat pump for your home except for a geothermal heat pump. There are several reasons for this.
1) No ductwork – central systems use ducts for air delivery. Those ducts all leak so you lose energy that way. They also usually run through unconditioned spaces like attics and wall spaces, so even when insulated, they lose energy. The air handler must also push all that air through those little ducts, which takes a lot of energy – this isn’t factored into any efficiency calculation, but it plays an important role. All told, you could buy a top of the line central system and it would be anywhere from 50%-75% as efficient as the mini-splits. Even a geothermal system will lose energy in all these ways, so the mini-splits often compare favorably to them.
2) The mini-splits have true variable speed compressors allowing them to modulate the heating/cooling output much more closely to your home’s needs. Even the best regular central systems have only a two-speed compressor, so it’s hard for them to match the heating/cooling needs anywhere as closely as the mini-splits.
Since you’re in a dry climate, the evaporative cooler can’t be beat for efficiency. My inclination would be to use that as your central cooling system and supplement it with the mini-splits as needed. The evaporative cooler will also add much needed humidity to your super-dry air.
Your existing air conditioning system uses probably at least three to four times as much as the mini-splits would. The Evaporative cooler should be even more efficient.
You’ve got natural gas, which is typically the cheapest method for heating (at least currently). However, if you were to outfit your home with several of these mini-splits, you would likely never have to turn on your central system.
The linesets for the mini-splits usually run outside the house and poke through right where the wall units are mounted. They encase the linesets in something that looks like a downspout. This gives easy access for maintenance and simplifies installation.
I’m a big believer in passive cooling for the southern and western exposures. Especially where you are, that sunlight can really heat things up. But if not possible, you may want to look into heat reflective window films.
As for dollars and cents, anything you do with a decent new system, central or not, is likely to cut your air conditioning bills in half compared with your existing unit. If you add the evaporative unit to the mix, you’ll do even better. The trick with the mini-splits is that they’re point source, so really you’d probably end up needing at least four of them to adequately cover your home. That’s going to add up to probably around $12,000. So you could get a top of the line central system and the evaporative cooler for less than that.
If I were in your shoes, I would probably stick with a central system upgrade, but augment it with the evaporative system to give you some super-efficient cooling. The central system would give you air distribution which will help to spread that cooling from the window evaporative unit around the house.
I would also get my ducts tested for leaks. It’s appalling how bad some duct systems can be and if you’re going to be spending close to $10,000 on upgrades, spending another few hundred on a professional duct test and some sealing would be worth it.
Hope that helps!