In July 2014, I purchased this GE GeoSpring heat pump water heater to replace my existing all-electric water that had sprung a leak. Admittdely, it was an impulse buy because Lowes was having a sale on them – probably to get rid of unwanted inventory because these have horrible reviews!
So why did I buy it? Because it was only a few hundred dollars more than a conventional electric water heater and I’d been wanting to get an integrated HPWH after my previous add-on HPWH died after just a year. Plus, based on the negative reviews, I felt that the people having problems were using earlier versions of the heater. So I’m crossing my fingers and hoping that it has a long, happy life.
Almost everything written in this article applies to all heat-pump water heaters. I’ll put the GE specific notes at the end.
What is a heat-pump water heater?
You may not know it but your refrigerator and air conditioner are examples of heat pumps. Through a process of compression, condensation and evaporation, they move heat from one place to another. In your refrigerator, that humming you hear when it runs is the compressor. The inside of the fridge is cold because the “heat” in the fridge is moved to the outside of the insulated box and blown into your kitchen. An air conditioner works exactly the same way – it cools the air inside the house and expels the heat outside.
The HPWH does the same thing except it uses the heat to warm the water in the tank. And the cold? If you feel the output behind the heater, you’ll see that the cold gets blown into the room. Heat the water, chill the room. Keep this in mind, we’ll come back to that later.
Why does a heat-pump water heater save energy?
Why would you spend twice (or more) the cost of a regular electric water heater? Because of the energy savings! Whether you want to reduce your electric bills or do what’s right for the environment, a HPWH promises to save lots of energy. How much? 50%-75%.
To answer the “why”, let’s look at how water heaters work.
A standard electric water heater works exactly the same as those coils you plug in and stick in a cup of water. Electricity flows through a wire, the wire heats up and that heat is transferred to the water. This process is about 99% efficient (excluding other losses outside your house). Electricity comes in, heat goes out. Simple. But if it’s 99% efficient, how can you save so much? That’s the magic of science!
A HPWH heats water indirectly through a process of compression, condensation and evaporation (sound familiar?). Instead of heating a piece of wire, the HPWH runs a compressor and a small fan. Remember, it works by *moving* heat from one place to another. So this process moves heat from your room into the water. The energy required is for the compressor and fan which is able to move heat into the water two to three times more efficiently than that electric wire.
Remember what I said about your refrigerator being a heat pump? In theory, if you put the hot coils (usually located under the fridge) in water, you would be heating water with your fridge, saving even more money! In the future, I believe more household appliances could be combined to virtually eliminate waste. But I digress…
So through magic, um, I mean science, the HPWH is able to heat water much more efficiently than a simple electric coil.
Added benefit – air conditioning and dehumidification
Previously I mentioned that the HPWH blows out cool air as a side effect of using a heat pump. A HPWH therefore acts as a small air conditioner! This is great in the summer when you want to cool your house. It may not be great in the winter, when you’re trying to heat the house!
You know that air conditioners also create a trickle of condensate. This is water extracted from the air that condenses on the cold coils. In the same way, the HPWH creates water that must be disposed of. If you’re lucky, you have a drain in the utility room where you can run the condensate line. Otherwise, you’ll have to pump the water to a drain line. It’s a small thing, but something you have to think about.
If you’re like most people, you’ve got the water heater in a utility room in the basement. Basements are usually somewhat humid so that dehumidification is welcome. This gives you an added energy savings because you might not have to run that energy-hog dehumidifier as much if you have a HPWH.
As an example, this summer, while heating water for my family of three, the HPWH produces about a gallon of water every day. That’s a pretty good amount of water being extracted from the air! And it’s noticeable. My utility room is distinctly cooler and drier than it used to be.
What if you don’t want cold air blowing into the room?
All modern HPWH’s let you select modes. For the summer, I set mine to heat the water 100% using the heat pump, so it’s most efficient. That’s also when it blows out the most cold air. When it’s cold out, you can switch it so that it acts like a conventional water heater and only uses electric heating coils to heat the water. In this mode, it’s silent and there’s no cold air or dehumidification. There’s also no energy savings.
In my case, I’ll use it year round because it’s in a basement utility room that’s effectively sealed off from the rest of the house. I want the dehumidification and having a room that’s a bit colder is good – I’ll use it as a cool storage room for food, just like a root cellar.
But if you’ve got it installed in your living space where you don’t want a cool breeze during the winter, you can always go back to normal electric heating mode so you get the best of both worlds.
Keep in mind, it’s not going to let your house get freezing cold. GE says: “In order to protect the heat pump system and for highest efficiency the GeoSpring heat pump will operate between 45°F – 120°F. Anything below or above this temperature range will cause the water heater to automatically operate in standard electric mode to continue to provide hot water.”
For the most part, installation of a HPWH is the same as any other electric water heater. Set it in place. Connect electric wires and plumb it in. It’s an easy job. But there are a couple extra considerations:
- As noted, you need to provide a place for the condensate to drain
- It extracts heat from the room, so you must install it in a room large enough to provide that heat without sucking too much warmth from the room. That means no small closet installations.
- It’s taller than an equivalent capacity water heater. Basically, take a normal 50 gallon water heater and add a foot to the height.
GE has specific recommendations as follows:
“The GeoSpring water heater should be installed in a clean, dry area as near as practical to the area of greatest hot water demand to prevent long un-insulated hot water lines from wasting energy and water. It is designed to go into any common indoor installation area including basements, attics, closets, and utility rooms. If the room is smaller than 700 cubic feet, the room should have a louvered door or a door which has vents installed near the top and bottom of the door. Each of these vents should have an area of 240 square inches.”
Install it. Get hot water. No special thought required if you don’t want to think about it.
However, if you want to take full advantage of the HPWH, you’ll want to familiarize yourself with it’s special features.
The photo to the right shows the control panel of the GeoSpring I’m using. You can see five modes:
- Heat Pump
- High Demand
There’s also up/down arrows to set the temperature and a couple other items. As you can see, I have mine set to 130F and the little green indicator light shows that it’s in heat pump only mode.
To make things easier, GE has also provided a description of each feature. These are described below:
- Heat pump only – exactly as indicated. Uses the heat pump for all the water heating. This is the most efficient mode but also the slowest to heat water and which cools the air the most. Note – by slow, it means it takes about an hour to reheat the tank fully after it’s been depleted. I’ve never found this to be a problem for multiple people taking showers, but if you take long showers or need to fill a bath, you have to consider this.
- Hybrid – uses both the heat pump and electric coils. This senses your operation, preferring to use the heat pump but uses the electric coil as needed to increase the ability to keep up with hot water demand.
- High demand – this mode tells the water heater that you’re going to be using a lot of water and forces it to use the electric heater even more to provide a greater hot water capacity.
- Electric – switches off the compressor and uses this exactly like a conventional electric water heater.
- Vacation – according to GE FAQ: “This feature is used when the homeowner is away from home for an extended period and hot water is not needed. In this mode, the temperature will drop the water temperature down to 50°F and will use the most efficient heating mode to conserve energy while the heater is sitting idle. The unit will automatically resume heating one day before the programmed return, so that hot water will be available.”
Real-life Energy Savings
So what’s the bottom line?
Before switching exclusively to the HPWH
As you know, I’m The Energy Geek, so I monitor everything. Prior to installing the GE GeoSpring heat pump water heater, I had three water heating systems in my home:
- Boiler fired water heater (connected to my oil fired boiler)
- Conventional electric water heater located below my wife’s shower (instant hot water, yay!)
- Small electric water heater located below the kitchen for dishes, hand-washing and laundry
I had a complex method of deciding which heater to use when. The heater under the kitchen always operated so that we’d get hot water for hand and dishwashing in a couple seconds rather than running the tap for 1-2 minutes before getting hot water (due to the weird plumbing in my house).
I used the electric water heater below my wife’s bathroom enabled all the time, but during the winter, I fed it how water from the main heating system boiler. This let me use heating oil (about half the cost of electric heating in my area) and a little electric as needed to maintain water temperature. Located where it was, it gave my wife instant hot water when washing hands and taking showers.
The boiler supplied the rest of the house, which really meant my bathroom and another bathroom.
It’s something of a crazy configuration but it optimized energy use and water savings. All told, during the summer, we used about 4 kilo-Watt hours (kWh) of electricity and 1/3 to 1/2 gallon of oil every day for a total cost of about $2/day for hot water at my utility costs.
After switching exclusively to the HPWH
Part of my switch-over to the HPWH was changing the plumbing so that I could more effectively use the HPWH as my single hot water source.
First, I ran a direct, 1/2″ water line to the kitchen from the utility room. Previously, the water had to travel a tortured path and used 3/4″ pipe. The larger pipe has more water capacity (2.3 gallons per 100ft) than the 1/2″ pipe (1.0 gallons per 100ft). This means I waste less water and get hot water faster to the kitchen. Plus, with the shorter run, it was even more efficient.
Next, since I’m in the process of switching my boiler, I’m not using any oil to heat water. In the future, I’ll have a new, high efficiency propane boiler that I can use for hot water during the winter, but I’ll cover that in a future article.
So how much energy am I using now? My daily electric use for water heating ranges from 2 to 5 kWh per day, averaging 3.19kWh. That equals $0.32 to $0.80 per day, with an average of $0.51/day – a savings of $1.49. Put another way, my water heating bill is now just about 25% of what it was before!
Is a heat-pump water heater worth it?
Assuming that I’m able to maintain it and it lasts just as long as a conventional electric water heater, how much am I saving?
For the moment, assume that the savings for the entire year equal what they are now – $1.49 per day. That about $540/year. Even if I don’t save as much during winter operation, I’ll be saving at least $350/year. That’s a payback on my investment in 1-3 years. For me, that’s a complete no-brainer! What other investments can I make that will yield 33%-100% return on my investment per year?
A quick comment on this – I’m assuming that the additional cost of the HPWH is $500-$700 compared with a simple electric heater. The numbers are back of the envelope and depend on your energy costs. I live near Philadelphia where electricity costs about $0.16/kWh and heating oil is $3-$4/gallon.
Summary of the pros and cons of a heat-pump water
- It saves money – water heating electric bills will be 1/2 to 1/3 compared to a conventional electric water heater
- It blows out cold air – effectively acts as a small air conditioner in the room where it’s installed
- It dehumidifies the air (more on this later)
- It costs more – You’re going to spend $1,000-$2,500 (USD) instead of $300-$700. Note, this is before installation costs
- It’s more complex – compressor, electronics and fan are more to break than a simple electric coil
- It blows out cold air (this can also be a benefit)
- Slightly more complex installation – it needs a place for the condensate to go
- Needs to be installed in an appropriate location
- It heats water more slowly than a pure electric water heater
- It makes noise like your refrigerator
All in all, after a month of operation, I’m very happy with this investment. The water heater has worked like a champ and is saving real money every day. What the long-term will bring, I don’t know. Hopefully, it won’t die in a year or two like some people have reported. But I’ll update if anything changes. Until then, I highly recommend heat pump water heaters for anyone currently using a conventional electric water heater and the time has come to replace it.
I enjoyed your article Ted. I considered the GE HPWH as well but since we have a Water Heater Closet we don’t have the required space for it. Good advice on disabling a recirculating pump, Taco has a D’Mand (push-button) system similar to the Chili system you recommended. Last year our 50-gallon Propane Water Heater sprung a leak and I rushed out to buy a standard 65-gallon Electric Tank. Propane prices ranged from as high as $2.95 per gallon, to as low as $1.80 per gallon and electric rates have stayed at or below $0.10 per kWh. A larger tank is required when switching to electric because of the recovery time – I had to rush because the government is foolishly mandated HPWH for anything over 55-gallons. We did something really unique, I installed (3) solar panels on my roof and installed the TechLuck Solar hybrid water heater solution. Last year we spent $69.72 in electricity to heat water for our home. The energy label on our propane water heater indicated that the average household used 283 gallons of propane, our annual propane use dropped over 200 gallons according to our records. 200 gallons of propane would have cost us $370 so we saved an estimated $300 this year. My only regret is that we didn’t buy a larger water heater tank, Solar powers the bottom heating element and Electricity powers the top-element. When we have guests in town we quickly exhaust the available hot water and it takes a little longer than we would like to heat the water after multiple showers – it would have been nice to have the additional capacity.
thanks for sharing your experience! Sounds like you made some smart decisions!
We built a home and installed the GE Geo Spring water heater. We have no issue with the amount of hot water and are not able to compare energy savings as we are new to this area and the new house has a totally different heating/cooling system (mini split) then we have had before. Our water heater is located in the utility room and I have it on the Heat Pump mode during the summer. It seems to run a lot (most of the day) and I was curious if that was normal. We did install a hot water circulation system which runs during the day as well so that may cause the heater to run more? For example, after a shower, it seems to run for 2-3 hours (fan blowing) before it stops. Is that normal? I assume even though the fan runs a lot, you are still saving on energy versus the traditional method of heating water? Thanks
I’m glad you mentioned the hot water circulation system – if it (the circulator) runs full-time, it is absolutely your culprit. The circulator turns your hot water pipes into radiators, so you’re basically heating your house all the time with wasted energy. It’s a double loss because then your air conditioner has to run more to cool the house.
My parents were talked into adding one of these to their solar heating system – what a catastrophe! I rendered the entire system useless because it wasted all the heat pumped into the tank by solar! I wanted to wring the neck of the plumber who charged them thousands of dollars to install this monstrosity.
There’s one system, called a chili pepper, which is the only system for hot water circulation that seems to be made right. You press a button right before you want to use hot water. It circulates water through the pipes until hot water reaches the faucet you want to use so the wasted energy is less than what you’d use to get hot water by running the faucet.
If you’ve got a hot water circulator that runs all the time, I strongly recommend turning it off and going back to the old way of running the faucet until you get water. Either that, add a remote control to the circulation pump and just turn on the pump a minute before you want hot water and turn it off when you’re done. Otherwise, it’s robbing you of your energy dollars.
Thank you for the information. We have turned off the water circulation pump and the heater is not running nearly as much. I think we will now see the real value of the heat pump water heater. Thanks again.
I bought one of these, and it is in our basement. (20×15 feet or so). The basement is cooler than I expected, so I am wondering 2 things.
-Does CCE mode override the other modes (i.e. heat pump, hybrid, etc)
-Which mode would be best for my situation? I live in Indiana, and I could also get a ducting kit, would that help?
You have a newer model than me so I had to investigate it CCE mode 🙂
For readers: CCE stands for Cold Climate Efficiency mode. Here’s their description. They also have this PDF file of the manual for this feature.
Based on that, my interpretation is that it only uses the heat pump when the temperature is in the range of 35F-120F. They don’t mention that it disables other modes of operation. My educated guess is that is an added feature – other options remain active, but the heat pump is disabled at below 35F.
How cold is your basement? Does it get down to those temperatures near freezing? Is it within the heated area of the house or is it more open to the outside? From what you said, it sounds like it’s unheated and gets pretty chilly. As such, I’d probably want to vent it outside during the colder weather and let it vent inside from spring to fall where the dehumidification could be useful.
Hope that helps!
Thanks for the response! The basement isn’t super cold, but it’s not exactly warm either. I would estimate around 50-60 degrees in the summer? It’s enclosed and has a furnace in it, but no vents.
We have been considering a HPWH for some time and finally made the plunge after doing lots of homework. Our home is near Vancouver so the idea of parasitically taking heat from our furnace to put into the water and get cold air as the byproduct does not work in the North. We have a SunPump now that uses roof mounted solar evaporator panels and a much larger capacity DC Inverter compressor with an 80 gal Thermal Battery that is working well. Our Solar Heat Pump Water Heater is big enough (36,000 BTU), to replace a ductless split heat pump, using a pair of hydronic fan coils to heat the main floor. Check out SunPump if you want a much better HPWH or live in a colder climate than the deep south. It is the best performance in this class. http://www.sunpump.solar
The SunPump looks like interesting technology – glad to see companies continue to innovate in this field.
To clarify, the GeoSpring and other heat pump water heaters are simple water heater replacements that are essentially plug-and-play in an existing home – for their cost (typically under $2000US) they offer a great bang for the buck and work in a wide variety of climates. While you typically don’t want to suck heat out of your home in the cold of winter, for the rest of the year, they work very efficiently and the cool, dry air they produce helps slightly reduce the air conditioning requirements of the home.
I am currently using the GE Connect to communicate with my Geospring 50 gal HPWH. Is there a way that I can just connect direct from my router to the Ethernet port on the water heater instead of using the Connect?
I wish I knew. I haven’t looked into that. Sorry.
I just purchased this water heater and I only had it installed for a couple days. What’s the most efficient setting I can have it on to save the most money?
Depends on your hot water usage, but I keep mine on heat-pump only mode. This is the most efficient way to run. If that works for you, then keep it there.
If you find that you run out of hot water, you can can set it to hybrid mode where the normal electric mode comes on if the heat pump can’t keep up.
I’m scrapping my Air Tap ATI66 HPWH after about 2 1/2 years (It was an unreliable disaster and AirTap has been a punk by not honoring their warranty). As a replacement I’m looking at the GE Geospring 80 gal unit. After discounts, tax credits, and rebates, the cost should be about free plus installation costs. I like the bigger 80 gal capacity because I figure I’ll be able to get almost all of my hot water using the heat pump instead of using the more expensive electric heating elements. Anyone have any feedback about the 80 gal GE unit?
I installed a GE hybrid water heater during my kitchen remodel. My PGE bill has gone down $15-$25 since I installed it in August. Our PGE bill was about $80-90 per month, our bills have $65-70, and we have our own well which I have a variable speed pump controller for. I also burn wood for heating, I run the furnace heat pump only on balmy days like today. I run in on the hybrid setting which mostly runs the heat pump. When the temp drops too low then the electric element kicks in. I installed it in my laundry room in the house so it it taking in air 65 plus all the time. When I heat the house with wood I’m in turn heating the water too. The air is cool but my laundry room isn’t cold. The noise is like a washer running. Wife didn’t care for it until PGE bills started coming. We got it last black friday, list $1100, on sale 799.00, Oregon Energy Trust kicked in $600.00, Federal kicked in $200.00. We got the unit for free. If your looking for a new water heater check it out.
Just curious, what was the add on HPWH you had that died after a year?
I have an American HPWH for two years. Been very happy with it. Only problem is it is loud when running. Much louder than a refrigerator. I have an Air Tap A-7 at my beach house that works great.
It was the AirTap AirGenerate unit.
They were really good about support, they sent me a new thermostat unit. Unfortunately, I couldn’t get the replacement working fine and was tired of diddling with it and ended up “retiring” the unit.
I’m building a house soon and your blogs have been quite educational. Stupid question: My electricity rate is only .08/kwh here in Florence, AL. That is great news but the problem I’ve been finding with all these more-costly energy efficient things makes it so that the “payback” period is measured in decades. For example, PV solar will take 20 years to recoup–the expected lifetime of the panels themselves. Same goes for extra insulation, and other advanced (costlier) construction techniques.
Since our summers are far more brutal than our winters, this little “air conditioner” interests me. But it will cost about $1000 more for this over a standard electric unit. I’m new at this so how do I calculate the payback period for this thing?
Like they say – there’s no stupid questions. If you’re wondering something, chances are good that thousands of others are as well.
You’re absolutely right, with “cheap” energy, the payback for efficiency is long, often “forever” in that you’ll replace the system before you get the payback.
Getting to your question – the air conditioning provided by the heat pump water heater is really minimal. I just see it as a bonus but it’s not going to replace the need for a “real” AC system.
Philosophically, I often think of lower energy consumption as a way of simply reducing our load on the overall “system” in which we live. Some would say that system is planet Earth, others might see it as the electrical grid or even your own local environment. There’s a lot of reasons people conserve.
Personally, I try to balance the practical and philosophical reasons. I look for some sort of reduced operational costs but I also look for other benefits. For example, the high-end heating and cooling systems can be more effective and comfortable because of the way they deliver heating/cooling. It’s like a car. I bought a VW Jetta diesel because I could run biodiesel and get 45mpg from it. But equally important was that it was a really practical car with great cargo space. How do I quantify that?
As a side note those solar panels actually have a much longer life span. Most these days are rated not to diminish by more than so many percent after 20-25 years. Here’s a nice little presentation with some graphs that show typical output of about 80% after 25 years. Not bad!
I always presented my energy consulting services as helping people be more comfortable, efficient and safe. As it turned out, most of my clients called me in to advise on comfort issues. Better windows, insulation, etc. greatly reduce drafts, cold spots and so on, so ultimately their families were happier. How’d that old advertisement go? “New windows…$2500. Better insulation…$1500. A smiling family…Priceless!”
“Philosophically, I often think of lower energy consumption as a way of simply reducing our load on the overall “system” in which we live. Some would say that system is planet Earth, others might see it as the electrical grid or even your own local environment. There’s a lot of reasons people conserve.”
Oh, I’m all about that. I’ve heavily researched building my house out of SIPs. I’ve looked at various basement structures. The lot I purchased has a perfectly situated southern exposure where lots and lots of passive solar will be used.
But, dad gummit, energy is too cheap here. With 100% passive solar (assuming I mortgage a system instead of buying it) will save me about 2% yearly. Buying a PV array will save me (on average) 4%. If I lived in San Diego, I’d save 40% so it’s a no brainer. But this is Alabama. Clean hydro and nuclear power is everywhere.
I’m definitely going with all LED. Those have finally come down to a digestible price.
So I guess I’m just ranting at how unfair it is to have all this cool new energy saving stuff out there that seems to save everyone awesome amounts of money AND help take care of our planet. Except for me. 😉
With an anticipated budget of $350k for a house, I just don’t have another 50 to 100k to “invest” in my future and hope it pays off in the long run. That stinks.
Wow, that’s really minimal saving! I can totally empathize with you.
Jim, you should pick up on Ted’s comments about comfort and safety. Don’t worry about PV and passive solar and all the other energy usage but instead concentrate on making the house tight and spend some money on low-e windows. My house was built long before I knew any of this stuff (I am a retired home and multi-family energy rater) but luckily it was built very tight. We don’t get winds blowing through here and we are snug. We put in low-e casement windows (Andersen) and that was about all the energy stuff we considered.
Now 20 years later I am tweaking the place but mostly for comfort. I added an ERV – energy recovery ventilator to replace two bath fans for two reasons. First, it brings in fresh air. I cook a lot and in the morning when I got up I could tell you what we had for dinner the night before. Now it just smells fresh. The other reason was that with standard bath fans you are taking in outside air (cold air for us, hot for you in summer) and you don’t know where that air is coming from. This way the air comes in, as one of my customers said, “on our terms”. Much more comfortable, the house smells better and I am in control.
I don’t have an attached garage but if I did I would definitely stop the air movement between the garage and the house. Carbon monoxide can get in that way. So can toxic things like paint and garden chemicals. Maybe put a 24/7 fan in the outside garage wall if you are really into venting the smells and dangers.
There are lots of other things you can do for comfort and IAQ, indoor air quality as well. Google those terms and you will see a lot. Try to ignore the energy saving aspects of what you read and go for comfort and safety because clearly energy is not your big consideration. Check out the rest of Ted’s blog and do some forum searching and learn what works and what does not. It is not rocket science but it does require some changes in thinking.
“Jim, you should pick up on Ted’s comments about comfort and safety. Don’t worry about PV and passive solar and all the other energy usage but instead concentrate on making the house tight and spend some money on low-e windows.”
Yeah. I just spent 20k on windows and doors (Pella) with the recommended e-values for my area.
But, dad gummit, I’m building this house with south-facing awesomeness and a “shed” type south-facing roof that would be awesome for all sorts of sun gathering stuff. Alas, every single measure I’ve looked at is way too expensive.
Seriously, a passive solar hot water heater is TWO THOUSAND DOLLARS? Why? This marvelous heater that Ted talks about is at least affordable but, again, with my electricity rate, payback is well over a decade. So it back to a very nice but standard gas heater.
2×6 (instead of 2×4) cannot be justified here, either.
So maybe I can justify some foamboard sheathing under the brick. That will not cost too much and will make me feel better about not being able to afford all this fancy “green” stuff.
And LED lights! Yessss.
I run a conventional oil boiler with a boiler mate water heater and use way too much oil in the summer just to make hot water. Nyle systems in Bangor ME makes a heat pump water heater that fits the boiler mate. I have been thinking to get one for summer use and then switch back to oil in the winter. But the Nyle has no back up system like an electric heat pump water heater with electric coils so I suspect its capacity is limited. Do you or any readers have experience with the Nyle on a boiler mate system?
P.S. Ted, I am the guy from your ESTAR class in Williamsport who, like you passed the ESTAR test. I have since retired and moved to Maine but still dabbling by experimenting with my own energy systems.
Hey Kent, I remember you well. Glad to hear from you. I’ve never been to Maine but hear it’s got some of the most beautiful scenery in the country.
Your experience with the indirect boiler heated water is the same as I experienced and is why I added the HPWH to my system. It was amazing, about 75% wasted oil when I measured it. I ended up wiring a timer into my boiler so it would only heat the water tank twice a day. That reduced oil consumption from about one gallon down to about 0.25 gallons. That worked great and was inexpensive but required taking showers at the right time or going to flip it back on manually. Not optimal for most people.
I haven’t had experience with the Nyle HP attachment for the boiler mate but I had something just like that. I’m assuming you’re referring to this unit: http://water.nyle.com/residential/
I like that it has a simple hookup to the water heater. Based on the ratings of the Nyle unit, the recovery might be slow. Its stated BTU output is only 6,275 – that’s about half of the newer integrated units. While I’ve had no issues running my new GE Geospring in heat-pump only mode this summer, it does seem that you’d have to be careful with your hot water consumption or you’d run out of hot water. I don’t know how many are in your household, so it’s difficult to say how effective it would be. For one person, no problem. For two, you’d probably want to space your showers by a few hours. It’s practicality is more of a lifestyle issue.
It’ll be interesting to hear if anybody else out there has experience with the Nyle unit and can comment.
https://polldaddy.com/js/rating/rating.jsThanks for the info Ted! Even now in 2017 it’s hard to find people’s actual savings when switching to a heat pump water heater.
My water heating efficiency from my oil boiler’s tankless coil seems to match up to your 25%. We use 0.6 gallons of oil per day in the summer. Our previous house had an older natural gas water heater which used about 11 therms/month. My internet research indicates that water heater was about 60% efficient.
So the energy making it to our water was: oil .6.251.41730=6.3765 therms/month at the new house and gas: 11.6= 6.6 therms/month at the old house. That’s close enough for a back of the envelope calculation.