I currently have a 17-year-old, gas water heater. It's not giving me a problem yet, but I'm getting nervous about it and investigating replacing it. I am trying to be both economic and reduce my reliance on fossil fuels, and HPWHs look like they might be a good option.

For some reason, the current WH is about as far away from the faucets as possible in my 1940's house, but by eliminating fume exhaust needs with a HPWH, I can relocated it to directly below the lines to the bathrooms and next to the kitchen. Luckily, that is also where the drain (for condensate) is too.

I have the skill/knowledge to install one from a big-box store myself, but I'm not sure I trust the quality. Although more expensive, I'd prefer to have a professional installation with warranty assurance and some authority with the manufacturer.

However, the plumbers I've reached out to for quotes have been discouraging of HPWHs in favor of just replacing with gas. I live in upstate NY, so I realize that the efficiency in my 60-degree basement won't be as good as a 85-degree garage in the south, but I thought it was still an economical choice over the lifetime of the unit -- especially if I run it in heat-pump mode only without the direct heater element.

Am I incorrect and a HPWH as a replacement for gas (rather than part of a high-efficiency new-home build) doesn't make sense in upstate NY? Are the plumbers just not familiar with HPWHs? (I saw somewhere that they are still only a couple percent of all new installs.)


  • AIUI, a heat pump water heater simply makes your home HVAC system work harder since it's going to be pulling heat for the water from the air in the house. You could draw in outside air, but in upstate, you get some pretty cold winters and your HPWH may not be able to get enough heat in those temps. It's handy in the summer, though, as it helps cool the house by drawing heat from the air to put into the water.
    – FreeMan
    Commented Mar 22, 2023 at 15:18
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    Additionally, "Any experience..." is a simply yes/no question, and "is it worth it" is entirely opinion based. There's a chance your question may get closed for that. You may want to remove the last sentence.
    – FreeMan
    Commented Mar 22, 2023 at 15:19
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    I'm posting this as a comment, not an answer since it's just my opinion. Depending upon how much HW you use, at Heat Pump water heater will def suck heat out of where ever it's located, esp. if in conditioned space. I gotta agree with @FreeMan, it will make your HVAC work harder during the winter esp. So lets think this thru: You get a HP WH which is expensive, unproven and complicated that is going to suck heat out of your house, then your HVAC will run more, if installed in a garage, it may turn it into a giant fridge. .....continued below. Commented Mar 22, 2023 at 16:26
  • I don't have AC, but I do run a dehumidifier in the basement where the WH is/will be. The basement is damp (not wet) and will never be a finished space. Some portion of the heat a HPWH draws from the basement air comes would from the earth since the basement isn't directly heated by the furnace and the heat in the rest of the house rises. Commented Mar 22, 2023 at 16:28
  • ...continued from above: Plain electric water heaters area dead simple stupid, but reliable. They have a tank, heating elements and thermostats. You could install the new WH closer to the point of delivery. That or leave it in it's current location and do a retrofit re-circ to make hot water more readily available. Commented Mar 22, 2023 at 16:30

2 Answers 2


The plumbers don't like complications.

The complication with a heat pump water heater at least, the single-unit ones, is that they are an air conditioner for the room. They are stealing heat from the room they're in. So the problem isn't that your basement is 60 degrees. The problem is that it will be much colder when the HPWH is going to town! You say "it'll come from the earth" but you might want to fact-check that belief. You're talking about a fair number of BTUs. Putting a 100 degree rise on a 30 gallon tank (250 pounds) is 25,000 BTUs.

Now you're thinking "I won't need that dehumidifier anymore". But let's think about latent heat, or the heat contained in the water vapor by virtue of it being vapor which is 1000 BTU per pound. When the dehumidifier condenses a pound (pint) of water, it adds 1000 BTU of heat into the room, because that is the latent heat of vaporization of water. That had to go somewhere, and it's not in the water vapor anymore - it's in the room now. Assuming it's working at 4 COP, it also adds 250 BTU of heat from its own mechanical function.

One reason the basement is 60 degrees (and not colder) is that 1250 BTU added to the room per pound of water condensed. You're going to lose that. Those BTU will now go into the hot water tank. In a 30 gallon (250 pound) tank, that 1250 BTU will raise the water in the tank 5 degrees F.

So yes, I am concerned about basement temperature, and I think your assumptions of "it's 60F because it's in contact with the earth" may be incorrect.

Now, a much more difficult thing to find, but certainly solves this problem, is a "mini-split" heat pump which has (as one of its heads) a water tank. Now, the heat pump lives outside and is taking heat from ambient outside air. If you think heat pumps don't work that cold, you're thinking of decrepit old American tech. Others have lapped us with new technologies using new refrigerants, that work just fine and sustain 2.5+ COP down to Chicago cold. That's why so many buildings in Ukraine have mini-splits on them.

If you're wondering how heat pumps can work that cold, think in Kelvin. It is numbered from absolute zero, which is what REAL cold is. -10°F is actually 250K and we enjoy home temperatures of 295K. Water tanks are best kept at 333K.

  • I looked a bit at the eco2 system, but the price is a LOT more than the single-unit HPWH, and will require a professional install. Commented Mar 23, 2023 at 16:56
  • @Teknowledgist Yeah, this stuff isn't commodity yet You could get it done on-the-cheap as a 2-stage system by adding any random mini-split to move heat from outdoors into the basement. Some are quite cheap and DIYable. And perfectly good modern Asian tech. Commented Mar 23, 2023 at 20:20
  • @Teknowledgist -- yeah, the eco2 stuff is expensive albeit very good specs-wise. there are other options in that space, but getting high enough temps to reliably zap legionella out of most R410 reverse cycle chillers is challenging. Commented Mar 23, 2023 at 23:51
  • Kelvin doesn't have degrees. It's just 295 K. Now, 1 K is the same as 1 degree C, but it doesn't get the degree symbol.
    – mdfst13
    Commented Jun 4 at 9:17

If you heat the house with gas or wood (seems likely in upstate NY if you have gas for the water heater now) it can make sense - just be sure to provide enough heat to the room where the HPWH (or its remote intake duct, which is a way to improve that) lives, since in winter you're heating water with gas via the heat pump - while in summer you get the benefit of free air conditioning/dehumidification and don't use gas for heating water. And, in your case, you get to put the heater where you need it for most efficient hot water distribution, which is a big win.

My personal experience with getting a professional installation quote (required for my local "rebate" program, making it a bad joke) was that professional installation and overly-marked-up-via-the-professional exactly-the-same-water-heater-as-a-big-box more than exceeded the price of buying two from a big box, even after the alleged rebate.

So, I'd go with the self-install option in your shoes.

However, since I heat with heat pumps, and will eventually add a wood boiler to that, I went with a plain old electric at 1/3 the price and less to go wrong with it, since it would be loading my heating heat pumps during their difficult season, and I really don't need AC 99% of the time. When I get the wood boiler rigged, that can heat the electric tank mostly. I'll revisit that in a decade or so when that one is due for replacement. My only gas option is propane which has been crazy expensive for years now in my area.

You might also look at your relative gas and electric rates, factoring in the coefficient of performance of the heat pump on the electric rates.

The math can also change if you are planning to add solar PV panels.

  • Power source pricing and unit efficiency are vital factors in calculating "is it worth it"! Don't forget to factor in the pricing/usage on the HVAC side since the HPWH will be drawing its heat from that.
    – FreeMan
    Commented Mar 22, 2023 at 17:42
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    @FreeMan yes exactly. Except speculating on future prices is inherent to the process. Also, electricity can be made at home - gas can't. Commented Mar 22, 2023 at 20:15

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