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Recommendation for 80-Gallon Heat-Pump Water Heater

kieran973 | Posted in Energy Efficiency and Durability on

Can anyone recommend a specific brand or model of 80 gallon heat pump water heater that should be expected to last with minimal repair issues for 10 or so years? Which heat pump water heaters are known or expected to be very durable and reliable, the kind of water heater you can install and then forget about for a decade – in other words, what is the Toyota Corolla of heat pump water heaters? This is anecdotal, but if you look through some of the online reviews from customers who have purchased heat pump water heaters from seemingly reliable brands – Rheem, AO Smith, etc – a general trend that I’m seeing is that those who purchased 1-2 months ago are excited and geeking out over the crazy efficiency gains, but those who purchased 1-2 years ago are extremely angry because their water heaters have had major repair problems and while the parts for these constantly breaking units are still under warranty, the expensive HVAC labor needed to troubleshoot/reinstall new parts is not, which then quickly wipes out most of the cost savings of switching to a HPHW in the first place.

A little bit about me and why I’m asking: my wife, son, and I just moved into a house in southern Connecticut and our 50 gallon A.O. Smith natural gas water heater is on the way out. I really don’t want to get another natural gas water heater – I want to get something electric. We’re about to put a 6.7 kW SunPower array on our roof which is expected to produce ~7400 kWh per year. If I go with a regular electric resistance water heater, yes it would be cheaper and less prone to repair issues, but my understanding is that this would consume 4,500-5,000 kWh a year, which would then leave very little kWh for other things (our lights and appliances are on track to consume 300 kWh/month or 3,600 kWh per year; we own a Nissan Leaf which consumes another 3,600 kWh per year; we’re also thinking about putting in heat pump mini-splits next year). So this lead me to consider, for example, the Rheem Prestige and Proterra HPHW’s which claim to consume only ~1,000 kWh per year. But if I buy a hot water heater that is going to break all the time, and/or I have to buy a new $1-2K HPHW every two years, A.) my family will kill me, and B.) it will negate a lot of the cost savings of getting a HPHW in the first place. I’m also not totally clear on whether a HPHW operating in southern Connecticut winters will simply make our gas boiler work harder to produce heat for the house, thereby negating the CO2 emissions reductions benefits of purchasing the HPHW. Anyway, any advice that people could offer would be much appreciated. Thanks.


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  1. BirchwoodBill | | #1

    I would look at a Artic heat pump or a Nordic heat pump. These can provide DHW, cooling and heating. The chiltrix has also been reported on GBA. For Minnesota weather I am leaning toward the Artic heat pump.

  2. BirchwoodBill | | #2

    Space Pak is also a nice HP

  3. brian_wiley | | #3

    I’m at 16 months with my AO Smith and it hasn’t had any issues; not even a hiccup.

    It is 50 gal, not 80 gal, so it’s conceivable that there’s a different compressor or something that would cause a difference in reliability with the two sizes. I couldn’t find any noticeable difference though on their website.

  4. user-2310254 | | #4


    I think this is one of those YMMV situations. Heat pump water heaters are more complicated than traditional gas or electric units. More complexity means more opportunities for things to go south. That said, my Rheem 80 gallon HPWH has been going strong for two years.

    Have you look at the Rheem Marathon line? An 85 or 105 gallon model might be worth considering.

  5. jwasilko | | #5

    Matt talked about the ones he's had in houses for 10 years in this video:

  6. Expert Member
    Michael Maines | | #6

    I know of quite a few AO Smith (and derivatives) in use for several years and have not heard of any problems yet.

  7. kieran973 | | #7

    Thanks, everyone, for your responses. I just learned that the Connecticut rebate on heat pump hot water heaters only applies to 55 gallon or smaller tanks. So I was thinking that instead of getting one 80 gallon tank like I had planned, I could get two 50 gallon tanks. The three sources of hot water draw in our house are a bathroom (sink and shower), another bathroom (another sink and shower), and the kitchen/laundry room (sink, dishwasher, washing machine). So maybe hook one tank up to the kitchen/laundry room and one tank to the two bathrooms? Has anyone tried anything like this? Would that be too complicated or an otherwise bad idea? Perhaps just one 50 gallon tank would be fine for us - after all, we have a 50 gallon gas hot water heater right now, and it's just my wife, my son, and I in the house - but my understanding was that with heat pump water heaters, you want to oversize so you don't run out of hot water all the time. Our house is 1500 sq ft of above grade living space. The hot water heater(s) would go in the unfinished basement. We average two showers a day, my toddler takes a bath once a day, we run the dishwasher once a day, and we do 3-5 loads of laundry a week (I also wash my hands a real real lot.) I guess I'm leaning toward A.O. Smith because I've heard slightly better things about their projected reliability. Any further thoughts that anyone has would be awesome.

    1. Expert Member
      NICK KEENAN | | #8

      Hook up the two tanks in parallel.

    2. verygood | | #17

      I can't believe nobody here has mentioned the Sanden unit. This unit can get around a COP of 5 which is almost double some of the other combo units. They are also low maintenance since the interior tank is just a stainless tank with no moving parts. If the exterior unit has an issue, the company is great about repairs and if its a large issue the exterior unit can be swapped out. They offer a 40 gal option that would qualify for the rebates for the smaller tanks and since the water is held at a hotter temp (cold water is added to the outgoing hot with a mixer valve) it behaves much bigger than 40 gallons.

      The downsides are the cost and potential need for an electrical upgrade. Other issue may be finding space on the exterior, keeping the water pipes on the exterior warm in the Connecticut winters (heat tape with a timer?), efficiency reductions in cold weather (although, still pretty impressive) and keeping the exterior unit up off the ground for snow, etc.

      I've had one in my home for 2 years and installed one of the first in NA back in 2014/15 and haven't had any issues with the dozen or so we've installed since then with the exception of a blown fuse on one last summer. It was an easy fix.

      Anyways, I just felt like it needed to be part of the discussion.

      1. user-2310254 | | #18


        I think many people would like to use it but are held back by the price. It is more than twice the cost of an 80 gallon hpwh, for example.

  8. _jt | | #9

    You will be fine with a 65 gallon Rheem. The only day I ran out of capacity was when I had a 2nd family of 6 over, and ran dishwashers, washing machines, showered, etc. at the same time!

    That was in heat pump only mode. In hybrid mode I'm sure it would be fine. Uses about a kw a day, and keeps the basement dry and cool.

    But - make sure to air seal your basement before you put it in. With an air sealed basement you will likely be warm enough to run in heat pump mode all year. If you have significant infiltration it will get cool enough to switch to electric only mode.

  9. rileyg | | #10

    We have had our 80 gallon AO Smith now for close to 4 years with no issues at all. It has been in efficiency mode since day one. Family of four with a wife who has a shower and a deep hot bath every day.

    1. bfw577 | | #12

      My 2nd generation GE Geospring has been running for 7 years in Heat Pump only mode. I believe Bradford White took over production and is still building them as the Aero Therm.

      I'm in CT as well and got it for free when the state rebate was like $1250 back when I bought it.

      I logged its electrical consumption a few years back and for my wife and I it was using around 1-2 kwh's a day. I have solar but that number would crush any fossil fuel based hot water heater. Monthly natural gas charges just to be connected are like $25 a month here before you use any actual gas.

  10. AP1210 | | #11

    We have had a Rheem 80 gallon Hybrid Electric water heater for about 18 months. Got it from Home Depot with an 18 month interest free deal.
    We have it installed in our basement to replace a 18 year old propane water heater for all typical domestic hot water usage. With a household of 4 (2 adults and 2 teenagers) I have been able to track daily usage via the app. In 2019, we averaged 3.02 kWh per day. In 2020, we have averaged a bit higher (closer to 5 kWh/day). I attribute this to COVID and the fact that my 1 teenager was home from college in early March, and my other daughter has been home from High School since March. And myself as well.
    We run the unit exclusively on the most efficient Energy Saving mode (completely on the heat pump) and haven't had any issues with respect to hot water supply. Even with up to 6 showers in a morning, supply seems fine.
    And, it comes with a 10 year warranty, which, according to my math, would completely pay back our investment and then some (as compared to propane at $3.00/gallon).
    And, we have a large solar array as well, so it just makes sense.
    In the winter, we have a wood stove in the basement, so the unit is very efficient pulling in hot air and discharging cool air. In the summer, its like free AC.
    If i had to do it again, I would have designed a cold air exhaust that would go to the outside in winter, and then switch to the room above (free AC) in the summer.

  11. kieran973 | | #13

    Revisiting this as well just had solar put on. Been considering the 50 gallon units for cost reasons — $700 less expensive than 80 gallon units, plus they qualify for a $750 rebate that the 80 gallon units don’t qualify for; plus skilled labor is expensive in my area and I’ve been getting really high total estimates to have these installed by local plumbers ($4.5k from one plumber; $6.7k from another). With the 50 gallon unit, I’d be concerned about the lower first hour rating, but I’ve read that thermostatic valve controls can increase the amount of available hot water. Is this true? If so, by how much? I read somewhere that when set to 140 F at the tank but then diluted down to 120 F delivery by the TVC, this increases available hot water by 30%. So to estimate the first hour rating of a 50 gallon HPWH with a TVC, could I just multiply the first hour rating by 1.3?

    1. charlie_sullivan | | #15

      In Southern CT, your incoming water temperature is probably about 55 F. You could measure it to check. If you mix one part 140F water with 0.3 parts 55 F water, you get 120.4 degree water, so that 1.3 rule sounds like it's correct for your region.

    2. bfw577 | | #16

      I am in Southern CT as well and those prices seems insane. The cheapest way to install would probably be to have an electrician run the 220 line to where the tank is going to be. I would then buy the tank and have it ready to go in the location its going to be installed. Call some plumbers and get a quote to have the water lines connected. A plumber should charge around $500 to connect it.

      Your replacing a regular gas tank with the water connections on top correct? Home Depot and Lowes sells flexible push on water heater lines so maybe diy is possible as well if your handy.

      Also, you can buy the tanks yourself and self installed them and still get the rebate in CT. The rebate is given as an instant discount when you check out at Lowes or Home Depot. 7 years ago when the rebate was better I walked out of Lowes with my tank and only paid like $150 for it. The rebate was $1k at the time. I installed it myself in less than an hour. 7 years later the unit has been running in heat pump only mode with zero issues.

  12. user-2310254 | | #14

    Do those install prices include the tank? Even so, the quotes are steep. Honestly, putting in a tank usually is not that complicated. You may need a new circuit. If so, get a quote from an electrician and consider DIYing the hookups. Also note that Rheem makes a 15 amp/220 volt version for services with less extra capacity.

    One advantage of 140 F is that your tank is less likely to harbor Legionnaires.

    If you have solar, I would be less concerned about the smaller tank. The array should make it more affordable to run the tank with electrical backup if necessary.

    1. bfw577 | | #20

      The default operating mode on these units is hybrid set to 120 and the yellow energy guide sticker is based off that mode. You would use way less than the energy guide sticker when operating in heat pump only mode. The AO Smith says right in the manual that the default setting is hybrid with a 120 temperature setting.

      I posted earlier my GE Geospring uses 1-2 kwhs a day and thats with it set to 130 with no mixing valve. Anthony posted earlier his 80 gallon averaged 3 kwhs a day. I would guess you would probably be looking at a 1-3 kwh/day consumption set to 140 in heat pump only mode. 1-2 kwhs/day seems to be a widely reported usage for 50 gallon tanks in heat pump only mode.

      I'm on solar as well but If I bought the electricity even at CT's high rates it would only cost around around $10 a month in electricity to run. These things are crazy efficient.

  13. kieran973 | | #19

    Thanks everyone. Yes, those are total prices - tank purchase plus installation, though this doesn't include paying an electrician to run the 220 line to the spot where the tank will go (this I'll have to arrange for separately).

    The tech specs on several of the AO Smith models and their derivatives are confusing and often contradict one another. But according to one spec sheet I found on the AO Smith Voltex 50 gallon HPWH, the first hour rating (gallons) is:

    Efficiency: 44.4
    Hybrid: 70
    Electric: 57.3

    So if turning the tank up to 140 F and then using a thermostatic mixing valve to dilute the delivered water down to 120 F by mixing it with 55 F water, then the unit would perform with a times 1.3 first hour rating of:

    Efficiency: 57.7
    Hybrid: 91
    Electric: 74.5

    Is this right?

    The 50 gallon AO Smith natural gas unit I currently have (9 years old), has a first hour rating of 88, so I guess the most comparable capacity would be the hybrid setting on the 50 gallon AO Smith Voltex HPWH.

    Is there a way to estimate the annual kWh usage of these units when setting the tank to 140 F and then using a thermostatic mixing valve? When the spec sheets only give one first hour rating, I believe they usually mean in hybrid mode, but the estimated annual kWh usage seems to be in heat pump/efficiency mode.

  14. norm_farwell | | #21

    We generally install Rheem hp water heaters and have not had problems. They are quite sophisticated--multiple operation modes, duct options, diagnostic menu, and an onboard leak sensor. My guess is most brands, sanden excepted, will have similar efficiency and your kwh will depend mostly on usage.

    Stiebel eltron is the top end--German engineering, highest efficiency, great warranty and product support--they replaced one of my client's tank for free when the issue was potentially not theirs. Also a powered anode so in theory the tanks should never corrode. But you get what you pay for.

    I'd figure $800 plus to install depending on local market.

    1. user-2310254 | | #22

      I hadn't looked at Stiebel recently and decided to check it out on one of the big box websites. Surprised to see it listed for only $500 more than the Rheem HPWH.

  15. kieran973 | | #23

    I found a local plumber who will install either the AO Smith Voltex 66 gallon or the Rheem Professional Prestige 65 gallon for about $3,400. These are not the box store models but the professional/contractor ones. That price includes capping off the gas pipe for my 9 year old gas hot water heater, hauling this water heater away, installing a thermostatic mixing valve, and doing all the necessary electrical work (running a 30 amp circuit about 15 ft from the service panel to the water heater and installing the automatic shut-off). The fact that the electrical work is included in the price is kind of winning me over because I was getting quotes for anywhere from $450 to $1200 to have a separate electrician do that.

    This plumber is advising me to go with the Rheem model. His main reason is that he thinks the Rheem model is more reliable than the AO Smith (the professional models - not the box store ones). I was a little surprised to hear this because I thought the AO Smith models were slightly more reliable. The Rheem is more gimmicky and techy with the auto leak detection, the wifi, the app where you can monitor your water heater from your phone, etc. So I would have thought there would be more opportunities for things to go wrong with the Rheem. The other issue is that, as I’ve been getting quotes from different plumbers in my area, every one but this one has quoted me for an AO Smith owned model (AO Smith, State, American, etc). So the AO Smith models seem more common in my area (southern CT) which makes me wonder if I could find plumbers willing to work on and/or find parts for the Rheem years down the line. According to this one plumber, if he needs to order replacement parts for a Rheem unit, he can only get them from Rheem directly, while he can get parts for AO Smith models at all kinds of local distributors. On the other hand, Rheem apparently makes their own compressors while AO Smith does not — I don’t quite follow how this would make the Rheem units more reliable, but that’s what this plumber said.

    Anyway, does anyone have any thoughts on the reliability of these two models? The reliability of Rheem vs AO Smith in general? The wisdom of getting a Rheem without knowing multiple plumbers who could theoretically work on it? I know the Rheem is slightly more efficient, and I like that its heat pump works down to 37 F (AO Smith’s only works down to 45 F), but I would be willing to take a slight efficiency hit for the sake of reliability and hassle-free future maintenance and repairs.....

  16. KevinChan02169 | | #24

    Hi, I'm also planning to use the same 50 gallon Rheem HP water heater for my renovation and I'm in Massachusetts, we have the same rebate structure from the utility. My problem is we are family of 6, so 50 gallon would not be sufficient for us. My plan is to install the HP water heater in the basement, and install a regular Electric 50 gallon in the 2nd floor laundry room, which is between the 2 bathrooms upstair. I would pipe the second water heater in series, and set the temperature of the HP water heater to be 140 and the upstair one to be 120, that way the upstair water will not comes on until the temp has drop below the set point. This will give me double the water capacity and also the hot water piping to the bathroom will be very short resulting a must faster hot water to the upstair bathrooms and laundry.

    1. user-2310254 | | #25


      I think your plan would work if your electrical service has sufficient capacity for two water heaters. But I would consider installing an 80 gallon HPWH to serve the entire house. It might be enough if the hot water demand is spread out enough. I also might see if I could split the demand so two smaller tanks could service each zone. If I needed a second tank, I would look at one of the smaller Rheem Marathons.

      That's just my nonprofessional, owner perspective. The experts might advise something else.

      1. KevinChan02169 | | #26

        What's the benefit of Rheem Marathons compare to conventional premium electric water heater?

        1. user-2310254 | | #27


          Plastic tank and thick insulation. I had an 85 gallon in a previous home and liked it very much.

  17. creativedestruction | | #28

    If you're looking for hot water efficiency gains with a long lifespan make sure you look into a heat recovery system. I've never heard of one failing, and if your existing plumbing setup is compatible the ROI can be quite short.

  18. KevinChan02169 | | #29

    I looked into that but I was only able to find them at the Home Depot website. Looks like a lot of manufacture stop making them, don't know if there are any issue with these.

  19. kieran973 | | #30

    I decided to go with the 65 gallon Rheem Professional Prestige model. Total cost to me after the $300 federal tax credit (which was just reinstated today I believe) is $3150. Thanks everyone for your input.

  20. kieran973 | | #31

    Just had this installed today. I’m confused though: which is the more efficient setting, Heat Pump or Energy Saver? One manual I found online says Energy Saver is more efficient, but I thought this was a “hybrid” setting which uses both the heat pump and the resistance elements, so wouldn’t Heat Pump as a purely heat pump only setting be more efficient?

    1. Jon_Lawrence | | #33


      My experience with the Rheem unit is that Heat Pump mode is exactly that, only heat pump regardless of how long your recovery time will be. Energy Saver Mode will run just the heat pump unless the recovery time is taking too long or the temp gets too low (not sure of how it determines that), in which case the electric heating element will kick in. I also think Energy Saver lets the temp fall more compared to Heat Pump mode before turning on the heat pump presumably so the heat pump will run longer and more efficient cycles. Of course not so far that the electric element kicks in. Ironically the app tells me I should be set the unit to Energy Saver mode and every time I do my energy use jumps. In Heat Pump mode the unit will draw 600 watts when operating. I have seen that jump to 1800 watts in Energy Saver mode.

      1. kieran973 | | #34

        OK, good to know. The app tells me the same thing - switch to Energy Saver for “maximum efficiency.” I guess I’ll have to experiment with both settings and monitor the usage. Does anyone know the recovery rate in heat pump mode?

        1. Jon_Lawrence | | #35

          Here is a picture of my 80-gallon Rheem energy consumption yesterday in Heat Pump mode. A few things to note:

          1) It is located in a conditioned basement in the same room as the wall mount Fujitsu indoor unit which is set to 66 degrees. The Rheem vents to a separate area of the basement.
          2) The first energy draw in the morning is from one person showering in a bathroom that is 2 stories directly above the unit. This shower is connected to a drain water heat recovery pipe so the water going into the heater from this shower is pre-warmed.
          3) The evening draws are from 3 other people showering and washing pots and pans. One of those showers was from the same bathroom mentioned above and the other 2 are from a bathroom located on the other side of the house that is not connected to the DWHR pipe but does have 0n-demand hot water so the water used to get the hot water to that shower was room temp water as opposed to cold municipal water.
          4) The set temp is 140 degrees and we have never run out of hot water despite the fact that one of the occupants likes to take long showers. I have seen the lower tank reach as low as 68 degrees, but the lowest I have seen the upper tank is 132 degrees.
          5) Month do date through the 29th, we have used just over 90 kWh's and the highest daily and hourly draw was on the day I had the unit set to Energy Saver mode.

  21. Mark_Nagel | | #32

    It's advisable for people to understand their water chemistry as that can have a big impact on the longevity of a given vessel/tank. Stainless or plastic might be a requirement in some cases.

    Also, and I don't know how many people do it, you're supposed to flush your tank(s) on a regular basis. I've been trying to flush mine once a year, but have come up a bit short of late (note to self: get with it!). I'm fortunate in that the my well's water chemistry is pretty decent- next to no calcium issues.

    As with any unit, be sure you've got the pieces in place to deal with a leaking or ruptured tank. I don't believe that warranties would cover damage to flooring and such. (I've read horror stories on damage to kitchen floors by refrigerator failures [from failing defrost components]: entropy lurks everywhere- all appliances can become unruly, so plan accordingly!).

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