Electric Heat Pump Water Heater

[Hot Sauce]

I'm looking to get an electric water heater, preferably using heat pump technology. At this point I'm indifferent to tanked vs tankless.

Current electricity rates are $0.16/kWh. Current natural gas rates are $1 per therm.

1) At these rates, does it make sense economically (within 25%) to go with electric heat pump over natural gas?

2) I'd be interested in hearing from others who have done research and/or currently use a heat pump water heater. What brand/model? Pros/cons/issues?

TIA

[inverter]

Have a Rheem ProTerra purchased in Dec 2021. Has been great thus far in terms of reliability, although it would be slightly loud if it were not in our basement.

[PNWHiker]

For the cost comparison, I found this site that may be useful for you: https://www.efficiencymaine.com/at-home ... omparison/

Plugging in your basic info says HPHW is cheaper, but you need to make sure your numbers are put in to be certain.

We've had a HPWH for almost two years - one at our former place and one at the house we purchased this past May. Both were in the garage, with plenty of enclosed volume to support them (they can't be in a small unventilated closet, for example). Both garages are uninsulated, and get to ~50-55º ambient in the winter. In both places the HPHW was a Rheem ProTerra. Previous place a 40gal, current place 50gal.

My observations from that experience:
- Energy usage is really low. The "annual cost" sticker on the sides have been almost perfectly spot-on for running costs.
- Set them in Energy Saver mode and let them go, *unless* you need really rapid recovery for some reason. As soon as you get the heating elements engaged your savings go out the window, so don't use them unless you really need to.
- Hot water recovery is a little slower than a normal electric, but you don't really notice it unless your tank is undersized.
- At least for the Rheem units we've had, the noise concerns have been a non-issue. Yes, they make noise, but if they're in a garage or otherwise away from the living spaces you don't notice the sound.
- They *do* cause some vibration. Our first one noticeably vibrated the house when we first put it in due to the fact that it was on a solid base and strapped to the wall for earthquake support. We put a vibration mat under the tank, between the tank and the straps, and behind the tank where it contacts the supporting wall, and the vibration transmission into the house is barely noticeable now.
- They create condensate just like AC units do, so the water has to be able to drain somewhere. You'll need a drain line to outside and/or a condensate pump to handle it. This is a major issue in some installations and can create lots of extra cost if there's no easy place for the condensate to be drained to.
- Look at all possible options for discounts and rebates - there are federal incentives, and many municipalities and utilities have additional incentives to stack on top.

Keep in mind that since they're still kind of a new thing, plumbers will try to gouge you on installation costs. Our first estimate was $6k installed (!), of which less than $2k was the unit cost. Absurd. I ended up doing the install at our last house myself. Don't let a plumber take advantage of you on it. Get multiple quotes and push back hard on exorbitant fees (demand a detailed breakdown of the cost). If you're handy, install it yourself. It's no harder than a standard tank water heater to install aside from the condensate point I made above.

Good luck!

[mchampse]

At minimum, you’ll get $2000 back from the federal government from the IRA bill. Your locality or state may also have an incentive.

[beardsicles]

We love our heat pump water heater. It's astonishingly efficient. Also have a Rheem.

[Irene]

Tankless electric is unlikely to work for most people as a whole-house heater - the ones that are big enough draw a lot of current in big spikes. They're mostly good as smaller point-of-use heaters (e.g., under the sink).

This thread from October might be useful if you haven't seen it already: viewtopic.php?t=440633

As I said on that thread, we're assuming we'll put in an electric water heater when our current gas one dies. Our choice is strongly influenced by the fact that the water heater is our last gas appliance, so we'll get rid of the base charge of having gas to the house (which is about half of our typical gas bill - I think it's $12.50 base charge, plus around $12.50 worth of gas - I think the current rate is $1.28 per therm). We might spring for a heat pump water heater, but our usage is low enough that it might make sense to just go with a plain electric resistance heater, especially as that is the simplest and longest-lasting kind of water heater. Our overall bill may go up a little bit, but the difference in purchase/installation price and presumed longevity should make up for it. If we ever put solar panels on the house, the marginal cost of a bit more electricity will mean even less to us. That said, I really like the idea of a HPWH, and it's not that I think they're all wildly unreliable or anything. Just more complex.

[z0r]

I have a rheem "PRO H50 T2 RH310UM" (it was their standard 50 gallon model, plumber version) in my garage. previously it was in the house in a closet. I did a self install both places, basically easy except it's much bigger then older units and the hookups are on the side

it was too loud in the indoor closet. in the garage I don't notice it

it gives some nice free AC in the summer. in the winter it cools the garage too much and I run my mini split to counteract it, but it's still nice because it's a very effective dehumidifier

energy wise it appears to meet specs. this year it's ranged from 60 kWh in July to 100 kWh in December (I guess plus some small mini split offset) for pretty heavy use. that's $6-10/month at our electricity price

[desiderium]

In addition to electric rates you should consider the installation and your climate to calculate savings. It takes the same amount of energy to heat the water for your home regardless of the technology. The heat pump gets ~1/2-2/3 of that energy from the ambient air rather than electricity. If the air surrounding the water heater is in a temperate garage (as in the example above) that energy is essentially free. Here is my own example: water heater is inside the building envelope, my heating season lasts 6 months and I don't have or need air conditioning (PNW). So for half the year my heating system would be rewarming the ambient air around a heat pump water heater. My electric rates are even lower than yours. Altogether, my energy savings would be much lower than a simple calculation might suggest.

[TomatoTomahto]

We HAD a heat pump water heater. It was installed in a too small room and was a failure. We replaced it with an electric water heater.

I’m a big fan of heat pumps and have 5 (2 ASHP (air sourced HP) and 3 GSHP (ground sourced HP). Make sure you have enough cubic feet around the water tank to make it work.

[yankees60]

I had my 80-gallon GE Heat Pump Water Heater installed December 2012.

Cost $1,000 with a $1,000 rebate. So I only paid the sales tax.

Cost $400 to be installed.

Somewhere around 2020 the fan died, meaning it was working as straight electric resistance.

It had a 10-year warranty was shipped for free a replacement fan. Paid an electrician $150 to install the fan. Going back to heat pump mode led to it using only 30% of the electricity it had been using in electric resistance mode. Over 12 years later from the outside the unit still looks brand new. Aside from that fan replacement there has been no other maintenance done to it.

It'd be difficult to use less hot water than me so just about all my usage is from standing heat loss and bringing it back to temperature. That temperature is 110 degrees which many people in this forum have told me too low.

It's located in my basement so subject to both basement temperatures and the temperature of the outside water coming into it. Since I'm in a bedroom on the farthest part of the house from where it located in the basement I've never heard it running.

About 340 kWh usage over last 11 months.

Here is how many kWh it has been using on a daily basis since December 1st:

12/01/24 0.8
12/02/24 1.3
12/03/24 1.1
12/04/24 1.1
12/05/24 1.1
12/06/24 1.4
12/07/24 1.1
12/08/24 1.2
12/09/24 1.1
12/10/24 1.4
12/11/24 0.8
12/12/24 1.2
12/13/24 1.1
12/14/24 1.4
12/15/24 1.1
12/16/24 1.3
12/17/24 1.2
12/18/24 1.6
12/19/24 1.1
12/20/24 1.4
12/21/24 1.3
12/22/24 2.9
12/23/24 2.3
12/24/24 2.5
12/25/24 2.2
12/26/24 2.4
12/27/24 2.9
12/28/24 2.6
12/29/24 1.8
12/30/24 1.0
12/31/24 1.5
01/01/25 1.2
01/02/25 1.0
01/03/25 1.2
01/04/25 2.1
01/05/25 2.9
01/06/25 2.5
01/07/25 3.4
01/08/25 2.5
01/09/25 2.2
01/10/25 2.4

Here are the daily basement temperatures for the same time period.

12/1/24 8:23 AM 50.7%
12/2/24 9:06 AM 49.5%
12/3/24 7:44 AM 49.1%
12/4/24 8:03 AM 49.1%
12/5/24 7:32 AM 49.6%
12/6/24 7:31 AM 49.6%
12/7/24 7:23 AM 48.9%
12/8/24 8:15 AM 48.9%
12/9/24 7:46 AM 49.5%
12/10/24 8:02 AM 50.9%
12/11/24 8:01 AM 49.8%
12/12/24 7:42 AM 51.1%
12/13/24 8:04 AM 48.6%
12/14/24 8:51 AM 46.8%
12/15/24 7:22 AM 46.0%
12/16/24 7:44 AM 46.6%
12/17/24 7:48 AM 47.1%
12/18/24 7:56 AM 48.2%
12/19/24 9:02 AM 48.6%
12/20/24 7:57 AM 48.4%
12/21/24 8:18 AM 48.6%
12/22/24 9:09 AM 45.9%
12/23/24 8:31 AM 43.7%
12/24/24 8:55 AM 45.0%
12/25/24 8:03 AM 46.2%
12/26/24 12:26 PM 44.6%
12/27/24 7:52 AM 43.5%
12/28/24 10:01 AM 44.8%
12/29/24 7:31 AM 45.5%
12/30/24 8:29 AM 47.3%
12/31/24 7:55 AM 49.1%
1/1/25 7:55 AM 48.4%
1/2/25 7:41 AM 47.8%
1/3/25 8:52 AM 47.3%
1/4/25 7:56 AM 46.6%
1/5/25 8:35 AM 45.9%
1/6/25 7:38 AM 45.5%
1/7/25 8:42 AM 44.6%
1/8/25 8:06 AM 44.6%
1/9/25 8:06 AM 44.6%
1/10/25 8:52 AM 44.2%


Finally ... I am in Western Massachusetts and my kWh cost is $0.37.

[just frank]

I've had an 80 gallon AOSmith HPWH for 12 years. Blew a control board after a power surge in year 4, the company fedexed me a new one and I replaced it myself. Otherwise, zero maintenance.

Allowed me to scrap an old boiler, saving me thousands in standby fuel costs.

It can make some noise, mine is in an attached semi-conditioned garage. I can just barely hear its rumble when its running, from my living room over the garage, if I listen for it.

My home energy monitor says it used 900 kWh in the last 12 mos, or about $160/year. Two people taking daily showers.

The newer ones are about 40% more efficient.

[PassivePanda]

I'm looking to get an electric water heater, preferably using heat pump technology. At this point I'm indifferent to tanked vs tankless.

Current electricity rates are $0.16/kWh. Current natural gas rates are $1 per therm.

1) At these rates, does it make sense economically (within 25%) to go with electric heat pump over natural gas?

2) I'd be interested in hearing from others who have done research and/or currently use a heat pump water heater. What brand/model? Pros/cons/issues?

TIA

Someone else referred you to the efficiency Maine calculator. You would save maybe $20 a year with the HPWH over NG tank. That's only if it's kept in HP-only mode. Hot water recovery is slower than gas WH. The HP cost is obviously higher, and may require installing 240v service. You can get the 120v model, but recovery is really slow, so might need to get a larger tank. If you have a large family, better to get tankless gas. Tax credit and rebate will bring down HP cost/installation. I don't like green rebates in principle because I think they are bad for society, but that's me. HP can be noisy. Plumbers are much more comfortable fixing a gas tank WH than HP. Gas WH are less susceptible to Legionella than electric if set at 140F.

[mkc]

I've described our issues with State/AO Smith 50 gallon heat pump water heaters in prior topics on them. 2 failed (same failure - heat pump died) in roughly 3 years, new construction (and properly installed) 2019; first failure 18 months later, unit replaced under warranty. Second unit failed about a year after that. Heat pump portion of unit is not serviceable, so you have to replace the entire unit (we had to pay for installation even under warranty). Unit cannot officially be forced to stay in resistive mode; it reverts back every 48 hours unless you know service codes.

Maybe when the units are more robust or maybe a different brand (sounds like those with Rheem are happy), but I would never recommend State/AO Smith units.

[just frank]

I've described our issues with State/AO Smith 50 gallon heat pump water heaters in prior topics on them. 2 failed (same failure - heat pump died) in roughly 3 years, new construction (and properly installed) 2019; first failure 18 months later, unit replaced under warranty. Second unit failed about a year after that. Heat pump portion of unit is not serviceable, so you have to replace the entire unit (we had to pay for installation even under warranty). Unit cannot officially be forced to stay in resistive mode; it reverts back every 48 hours unless you know service codes.

Maybe when the units are more robust or maybe a different brand (sounds like those with Rheem are happy), but I would never recommend State/AO Smith units.

Yikes. Clearly a design/manufacturing problem. Mine (earlier model in 2012) has been a champ.

The fundamental tech here is VERY similar to a refrigerator or window AC unit... can certainly be built to last for many years. Even if there are some lemons.

[prioritarian]

My observations from that experience:
- Energy usage is really low. The "annual cost" sticker on the sides have been almost perfectly spot-on for running costs.
- Set them in Energy Saver mode and let them go, *unless* you need really rapid recovery for some reason. As soon as you get the heating elements engaged your savings go out the window, so don't use them unless you really need to.
Good luck!

Energy savings are even lower if you set "Heatpump" mode which disables the electric element entirely.

[prioritarian]

It takes the same amount of energy to heat the water for your home regardless of the technology.

This is not correct. Heatpump water heaters are ~3.5x more efficient than electric resistance and 5-8x more efficient than gas.

[z0r]

In addition to electric rates you should consider the installation and your climate to calculate savings. It takes the same amount of energy to heat the water for your home regardless of the technology. The heat pump gets ~1/2-2/3 of that energy from the ambient air rather than electricity. If the air surrounding the water heater is in a temperate garage (as in the example above) that energy is essentially free. Here is my own example: water heater is inside the building envelope, my heating season lasts 6 months and I don't have or need air conditioning (PNW). So for half the year my heating system would be rewarming the ambient air around a heat pump water heater. My electric rates are even lower than yours. Altogether, my energy savings would be much lower than a simple calculation might suggest.

I'm in the pnw (I5 pnw, not desert/mountain/coastal - as we have at least these four major climate types) - I would flip your thinking from "I don't value the free AC" to "I have six months a year where I don't need to heat the house - and the heat removed by the hpwh is free - and only neutral otherwise"

the winter dehumidifier aspect has a twist also - when it sends the water down the pipe, it leaves behind the heat of vaporization. this can give an effective COP of 2-3 (until the water is gone, I don't think there's enough to make this effect that big). I don't have data but my estimate is that my garage mini split does not need to make-up the entirety of what the hpwh consumes. maybe only half or less, depending on my goal for the garage's temp (example, I've had it in freeze protection mode for a month now, it hasn't used any energy, while I've been between garage projects). dehumidification is exactly what you don't want in a pnw house inside the living space, though. it's instructive that my local utility gives their hpwh rebate for indoor or garage installs, ducted or not ducted (they specifically mention these cases) - the units have enough positive payoff, according to someone's modeling

my install cost around $500 after rebates, I estimated payoff (garage case) at 3-4 years at 10 cents/kWh and heavy family use, maybe 4-5 years indoors. I've had it 2.5 years now. I figured any payoff sooner than the warranty time (10 years) was a win, I was due for a new water heater anyway. you're right that at full retail the payoff time would probably be too long on these, for low energy cost areas

another trick - a friend in coastal pnw, where it basically never freezes, has a garage unit and installed an exhaust pipe (but not an intake). the intake air is from leakage of outside air back in. the garage is more comfortable than without the pipe (he tried it both ways) and it gets the heat drain closer to "free" in the winter. I looked at ducting mine but the dehumidification is valuable enough that I don't think I'll bother. most of these units have available duct adapter kits so you can connect exhaust only, or both, to the outside

[desiderium]

It takes the same amount of energy to heat the water for your home regardless of the technology.

This is not correct. Heatpump water heaters are ~3.5x more efficient than electric resistance and 5-8x more efficient than gas.

Misunderstanding. The thermodynamic properties of water (energy absorbed in raising x mass by y degrees) is independent of the source. In my post I indicated that a HPWH gets 1/2-2/3 of that energy from the ambient air (i.e., not from the grid). If it is a little more efficient than that, great.

[desiderium]

In addition to electric rates you should consider the installation and your climate to calculate savings. It takes the same amount of energy to heat the water for your home regardless of the technology. The heat pump gets ~1/2-2/3 of that energy from the ambient air rather than electricity. If the air surrounding the water heater is in a temperate garage (as in the example above) that energy is essentially free. Here is my own example: water heater is inside the building envelope, my heating season lasts 6 months and I don't have or need air conditioning (PNW). So for half the year my heating system would be rewarming the ambient air around a heat pump water heater. My electric rates are even lower than yours. Altogether, my energy savings would be much lower than a simple calculation might suggest.

I'm in the pnw (I5 pnw, not desert/mountain/coastal - as we have at least these four major climate types) - I would flip your thinking from "I don't value the free AC" to "I have six months a year where I don't need to heat the house - and the heat removed by the hpwh is free - and only neutral otherwise"

the winter dehumidifier aspect has a twist also - when it sends the water down the pipe, it leaves behind the heat of vaporization. this can give an effective COP of 2-3 (until the water is gone, I don't think there's enough to make this effect that big). I don't have data but my estimate is that my garage mini split does not need to make-up the entirety of what the hpwh consumes. maybe only half or less, depending on my goal for the garage's temp (example, I've had it in freeze protection mode for a month now, it hasn't used any energy, while I've been between garage projects). dehumidification is exactly what you don't want in a pnw house inside the living space, though. it's instructive that my local utility gives their hpwh rebate for indoor or garage installs, ducted or not ducted (they specifically mention these cases) - the units have enough positive payoff, according to someone's modeling

my install cost around $500 after rebates, I estimated payoff (garage case) at 3-4 years at 10 cents/kWh and heavy family use, maybe 4-5 years indoors. I've had it 2.5 years now. I figured any payoff sooner than the warranty time (10 years) was a win, I was due for a new water heater anyway. you're right that at full retail the payoff time would probably be too long on these, for low energy cost areas

another trick - a friend in coastal pnw, where it basically never freezes, has a garage unit and installed an exhaust pipe (but not an intake). the intake air is from leakage of outside air back in. the garage is more comfortable than without the pipe (he tried it both ways) and it gets the heat drain closer to "free" in the winter. I looked at ducting mine but the dehumidification is valuable enough that I don't think I'll bother. most of these units have available duct adapter kits so you can connect exhaust only, or both, to the outside

You have obviously done a deep dive, which was really my main point: that you need to make adjustments to the claimed efficiency based on your installation and climate circumstances in order to accurately estimate savings.

[ScubaHogg]

Have a Rheem ProTerra purchased in Dec 2021. Has been great thus far in terms of reliability, although it would be slightly loud if it were not in our basement.

I’ve had two at this point. We are a family of four and it just absolutely cannot keep up with even modest usage. So now I run it in “high demand” all day and heat pump all night. I doubt I’ll ever recover the premium price through electricity savings. I definitely wouldn’t purchase again

We do keep ours in the garage, but even when the garage is above 70F the HPWH fills very slowly and has basically no real time heating ability.

[Cyrah]

Heat pump water heaters are awesome for the environment, but the economics depend heavily on your climate and usage. At those rates, it might be close, but I'd run some serious numbers using a calculator that factors in your local climate and family size. I've heard good things about the AO Smith heat pump models, but honestly, research is key here.

[just frank]

Have a Rheem ProTerra purchased in Dec 2021. Has been great thus far in terms of reliability, although it would be slightly loud if it were not in our basement.

I’ve had two at this point. We are a family of four and it just absolutely cannot keep up with even modest usage. So now I run it in “high demand” all day and heat pump all night. I doubt I’ll ever recover the premium price through electricity savings. I definitely wouldn’t purchase again

We do keep ours in the garage, but even when the garage is above 70F the HPWH fills very slowly and has basically no real time heating ability.

I went for an 80 gallon unit for my family of 4 to get more capacity, also in a garage. Never had a problem in heat pump mode. I installed (very nice) low flow shoer heads at the same time.

One daughter who liked to stand in the shower would run out of water after about 90 minutes. That was a feature and not a bug. She would do that at 9PM, and the water would be back for Mom and Dad's shower in the morning.

[mkc]

I've described our issues with State/AO Smith 50 gallon heat pump water heaters in prior topics on them. 2 failed (same failure - heat pump died) in roughly 3 years

Yikes. Clearly a design/manufacturing problem. Mine (earlier model in 2012) has been a champ.

The fundamental tech here is VERY similar to a refrigerator or window AC unit... can certainly be built to last for many years. Even if there are some lemons.

I agree - there's no reason these shouldn't be as reliable or serviceable as other appliances. Our experience with State/AO Smith units has shown that not to be the case (at least for that manufacturer) and having to scrap the entire unit each time negates any intended benefits.

[ScubaHogg]

I went for an 80 gallon unit for my family of 4 to get more capacity, also in a garage. Never had a problem in heat pump mode. I installed (very nice) low flow shoer heads at the same time.

One daughter who liked to stand in the shower would run out of water after about 90 minutes. That was a feature and not a bug. She would do that at 9PM, and the water would be back for Mom and Dad's shower in the morning.

Well i have no idea what i could be doing wrong. Theres zero chance i would get anywhere near that.

If you have tips I’m all ears. The owners manual is useless.

[yankees60]

This topic provoked me to look at the manual again for my now 12-year-old unit.

I had thought I'd read on the internet that below a certain temperature one should switch the mode from heat pump to hybrid. But the manual makes no reference to the temperature surrounding the heat pump.

The temperature in my basement has been in the 40s, with this morning being at 44.

[z0r]

I went for an 80 gallon unit for my family of 4 to get more capacity, also in a garage. Never had a problem in heat pump mode. I installed (very nice) low flow shoer heads at the same time.

One daughter who liked to stand in the shower would run out of water after about 90 minutes. That was a feature and not a bug. She would do that at 9PM, and the water would be back for Mom and Dad's shower in the morning.

Well i have no idea what i could be doing wrong. Theres zero chance i would get anywhere near that.

If you have tips I’m all ears. The owners manual is useless.

consider installing a thermostatic mixing valve at the water heater and then turn its temp up. at higher water temps the heat pump doesn't work as well but you'll be able to keep it in heat pump mode more since you'll have more effective capacity, this is still almost certainly a win even if you crank the temp to the max (160?)

[just frank]

I went for an 80 gallon unit for my family of 4 to get more capacity, also in a garage. Never had a problem in heat pump mode. I installed (very nice) low flow shoer heads at the same time.

One daughter who liked to stand in the shower would run out of water after about 90 minutes. That was a feature and not a bug. She would do that at 9PM, and the water would be back for Mom and Dad's shower in the morning.

Well i have no idea what i could be doing wrong. Theres zero chance i would get anywhere near that.

If you have tips I’m all ears. The owners manual is useless.

Well, if the tank is already hot, then the 'first hour' rating FHR in gallons of hot water is the tank volume plus what little more hw it can make.

I measured the gallons per minute of the shower heads I was using, with a bucket and a stopwatch, and figured out how many minutes I would get. My FHR was like 90 gallons (on an 80 gallon unit) and the shower head in my showers was rated 1.3 gpm, but ran a little lower bc of low pressure, like 1.2 gpm. 90/1.2 = 72 minutes of (undiluted) HW. Mixing in a little cold to keep it from scalding (we run ours at 120°F), we expected to get about 90 minutes of shower time.

My showers were about 10 minutes, my wife's about 15. Math suggests we could easily get 4-6 such showers on a tank. And indeed, we and houseguests could all shower in the morning and never once run out of water. Only my teen daughter standing under it for close to 90 minutes got there. She was not allowed to do that in the AM when others needed to shower.

So, maybe you have a jacuzzi tub, or 4 gpm shower heads, or showers with multiple heads. Then THAT would be a problem.

[just frank]

This topic provoked me to look at the manual again for my now 12-year-old unit.

I had thought I'd read on the internet that below a certain temperature one should switch the mode from heat pump to hybrid. But the manual makes no reference to the temperature surrounding the heat pump.

The temperature in my basement has been in the 40s, with this morning being at 44.

It almost certainly does that switch automatically. Mine does it in the lower 40s (maybe a couple weeks per year). The issue to defrosting the coils... if the coils get to 32°F in operation, they can frost up, and the HPWH makers just switch to the element rather than dealing with a complex defrosting circuit.

[ScubaHogg]

So, maybe you have a jacuzzi tub, or 4 gpm shower heads, or showers with multiple heads. Then THAT would be a problem.

I’ve literally run the heat pump for 9 uninterrupted hours without it completely filling the tank (garage probably in the mid 50s)

I can’t conceive how little hot water my family would need to use a day to make that viable. There’s showers, baths, laundry, dishes…

[ScubaHogg]

consider installing a thermostatic mixing valve at the water heater and then turn its temp up. at higher water temps the heat pump doesn't work as well but you'll be able to keep it in heat pump mode more since you'll have more effective capacity, this is still almost certainly a win even if you crank the temp to the max (160?)

I’ll look into it. But if the heat pump can basically just never get a hot tank idk it matters

[inverter]

Have a Rheem ProTerra purchased in Dec 2021. Has been great thus far in terms of reliability, although it would be slightly loud if it were not in our basement.

I’ve had two at this point. We are a family of four and it just absolutely cannot keep up with even modest usage. So now I run it in “high demand” all day and heat pump all night. I doubt I’ll ever recover the premium price through electricity savings. I definitely wouldn’t purchase again

We do keep ours in the garage, but even when the garage is above 70F the HPWH fills very slowly and has basically no real time heating ability.

How big is your tank? Sounds like it is undersized for your demand.

[cmr79]

consider installing a thermostatic mixing valve at the water heater and then turn its temp up. at higher water temps the heat pump doesn't work as well but you'll be able to keep it in heat pump mode more since you'll have more effective capacity, this is still almost certainly a win even if you crank the temp to the max (160?)

I’ll look into it. But if the heat pump can basically just never get a hot tank idk it matters

How long does recovery take when your garage is at or above 70F? Mine is in my basement which is unfinished and isn't directly heated (it stays close to 60 from heat loss from the floor above, HVAC, etc), and we don't have any issues with a family of 4 with an 80 gallon AO Smith unit. We did run out of hot water once while in heat pump only mode while my extended family was visiting shortly after it was installed, but that was 7 adults and several kids bathing in a short span along with dishwasher and laundry running...something it ultimately handled without issue this past Christmas when the same family members visited and I switched it into hybrid mode.

[ScubaHogg]

I’ve had two at this point. We are a family of four and it just absolutely cannot keep up with even modest usage. So now I run it in “high demand” all day and heat pump all night. I doubt I’ll ever recover the premium price through electricity savings. I definitely wouldn’t purchase again

We do keep ours in the garage, but even when the garage is above 70F the HPWH fills very slowly and has basically no real time heating ability.

How big is your tank? Sounds like it is undersized for your demand.

65 gallons

But regardless of size, should it not be able to create a full tank of hot water after 9+ hours?

[ScubaHogg]

I’ll look into it. But if the heat pump can basically just never get a hot tank idk it matters

How long does recovery take when your garage is at or above 70F? Mine is in my basement which is unfinished and isn't directly heated (it stays close to 60 from heat loss from the floor above, HVAC, etc), and we don't have any issues with a family of 4 with an 80 gallon AO Smith unit. We did run out of hot water once while in heat pump only mode while my extended family was visiting shortly after it was installed, but that was 7 adults and several kids bathing in a short span along with dishwasher and laundry running...something it ultimately handled without issue this past Christmas when the same family members visited and I switched it into hybrid mode.

Stories like yours is why I think I’m doing something wrong. But since it’s been the same thing for two back to back heaters I can’t imagine what it is

[z0r]

How big is your tank? Sounds like it is undersized for your demand.

65 gallons

But regardless of size, should it not be able to create a full tank of hot water after 9+ hours?

I looked at my energy monitor logs, my 50 gallon set to 145 F in a 50 F garage takes about 7-8 hours to fully recover if we drain it completely, 9 hours seems long if yours is set to 120 F but could be about right if it's turned up. on most days mine runs for 3-4 hours because we don't drain it. the nice thing about turning it up is you'll get extra effective capacity, hot water will last longer and now maybe it'll run for 12, 15, 18 hours a day but could stay in heat pump mode

[ScubaHogg]

65 gallons

But regardless of size, should it not be able to create a full tank of hot water after 9+ hours?

I looked at my energy monitor logs, my 50 gallon set to 145 F in a 50 F garage takes about 7-8 hours to fully recover if we drain it completely, 9 hours seems long if yours is set to 120 F but could be about right if it's turned up. on most days mine runs for 3-4 hours because we don't drain it. the nice thing about turning it up is you'll get extra effective capacity, hot water will last longer and now maybe it'll run for 12, 15, 18 hours a day but could stay in heat pump mode

Maybe we just use a lot of hot water? Maybe they are for folks who use very minimal hot water. In researching I certainly never conceived that it would take a full work day to reheat a single tank

[just frank]

Yeah, I think mine takes about 6 hours to fully recover after being drained (only happens rarely now that the teen is grown), at 50°F garage temp. There is useable hot water after 3-4 hours (at the top of the tank). So I don't know what is going on.

Laundry, dishwasher, etc only use low volumes of water... so aren't really issue. Only bathtubs and showers use enough to drain a tank.

And then, measurement is key. Your 'normal' showerhead could use 4 gpm or 1.5 gpm. Only way is to know is measure.

Up to the 80s 4 gpm was the standard. Now most are <2.

If its not your shower heads or bathtub usage, then you have a hot water leak somewhere.

[Valuethinker]

Yeah, I think mine takes about 6 hours to fully recover after being drained (only happens rarely now that the teen is grown), at 50°F garage temp. There is useable hot water after 3-4 hours (at the top of the tank). So I don't know what is going on.

Laundry, dishwasher, etc only use low volumes of water... so aren't really issue. Only bathtubs and showers use enough to drain a tank.

And then, measurement is key. Your 'normal' showerhead could use 4 gpm or 1.5 gpm. Only way is to know is measure.

Up to the 80s 4 gpm was the standard. Now most are <2.

If its not your shower heads or bathtub usage, then you have a hot water leak somewhere.

Laundry, dishwasher, etc only use low volumes of water... so aren't really issue.

Do American appliances connect to a hot tap? In the UK, pretty much 100% connect to a cold water line. It's why dropping the wash temperature from 40 degrees C to the now-recommended by clothing manufacturers, 30 degrees C, makes such a difference to the energy used in a washing machine (ie the input water is about 10-12C say).

[cmr79]

Yeah, I think mine takes about 6 hours to fully recover after being drained (only happens rarely now that the teen is grown), at 50°F garage temp. There is useable hot water after 3-4 hours (at the top of the tank). So I don't know what is going on.

Laundry, dishwasher, etc only use low volumes of water... so aren't really issue. Only bathtubs and showers use enough to drain a tank.

And then, measurement is key. Your 'normal' showerhead could use 4 gpm or 1.5 gpm. Only way is to know is measure.

Up to the 80s 4 gpm was the standard. Now most are <2.

If its not your shower heads or bathtub usage, then you have a hot water leak somewhere.

Laundry, dishwasher, etc only use low volumes of water... so aren't really issue.

Do American appliances connect to a hot tap? In the UK, pretty much 100% connect to a cold water line. It's why dropping the wash temperature from 40 degrees C to the now-recommended by clothing manufacturers, 30 degrees C, makes such a difference to the energy used in a washing machine (ie the input water is about 10-12C say).

Yes, dishwashers and washing machines both typically have both hot and cold water inlets here. Dishwashers usually still have a heating element and boost the hot water temp further to be able to sanitize, but I'm not sure if washing machines do.

[PNWHiker]

My observations from that experience:
- Energy usage is really low. The "annual cost" sticker on the sides have been almost perfectly spot-on for running costs.
- Set them in Energy Saver mode and let them go, *unless* you need really rapid recovery for some reason. As soon as you get the heating elements engaged your savings go out the window, so don't use them unless you really need to.
Good luck!

Energy savings are even lower if you set "Heatpump" mode which disables the electric element entirely.

It may be a bug in Rheem's programming (either the app or the unit), but when I've had my Rheem set to Heat Pump mode I have seen the elements come on after heavy use like from a shower. I have never seen the elements activate when in Energy Saver mode. YMMV.

[yankees60]

Yeah, I think mine takes about 6 hours to fully recover after being drained (only happens rarely now that the teen is grown), at 50°F garage temp. There is useable hot water after 3-4 hours (at the top of the tank). So I don't know what is going on.

Laundry, dishwasher, etc only use low volumes of water... so aren't really issue. Only bathtubs and showers use enough to drain a tank.

And then, measurement is key. Your 'normal' showerhead could use 4 gpm or 1.5 gpm. Only way is to know is measure.

Up to the 80s 4 gpm was the standard. Now most are <2.

If its not your shower heads or bathtub usage, then you have a hot water leak somewhere.

Laundry, dishwasher, etc only use low volumes of water... so aren't really issue.

Do American appliances connect to a hot tap? In the UK, pretty much 100% connect to a cold water line. It's why dropping the wash temperature from 40 degrees C to the now-recommended by clothing manufacturers, 30 degrees C, makes such a difference to the energy used in a washing machine (ie the input water is about 10-12C say).

Obviously, for the heat pump water heater ... it is getting fed by cold ground water. As I write this ... probably at its coldest all year.

In the nearly 43 years I've owned my house I've never used anything but cold water in the washing machine. I do have the option of putting hot water into it.

[prioritarian]

Energy savings are even lower if you set "Heatpump" mode which disables the electric element entirely.

It may be a bug in Rheem's programming (either the app or the unit), but when I've had my Rheem set to Heat Pump mode I have seen the elements come on after heavy use like from a shower. I have never seen the elements activate when in Energy Saver mode. YMMV.

It's my understanding that Rheem hybrid heaters will use resistance heating if the heat pump is not able to bring up the temperature to the set point in a given amount of time. It's possible that you have a dud compressor, that your water is exceptionally cold, or that the water heater is in a very cold environment. My Rheem proterra is in a basement that ranges from 55-65 F all year.

[inverter]

Yes, dishwashers and washing machines both typically have both hot and cold water inlets here. Dishwashers usually still have a heating element and boost the hot water temp further to be able to sanitize, but I'm not sure if washing machines do.

BTW - if you do have a dishwasher with only one water connection (like my family's Miele) and have a heat pump water heater, you should connect it to hot water to save some cents each time you run it.

[Auream]

Yes, dishwashers and washing machines both typically have both hot and cold water inlets here. Dishwashers usually still have a heating element and boost the hot water temp further to be able to sanitize, but I'm not sure if washing machines do.

BTW - if you do have a dishwasher with only one water connection (like my family's Miele) and have a heat pump water heater, you should connect it to hot water to save some cents each time you run it.

AFAIK the vast majority of dishwashers only have one water inlet. In the U.S. we normally plumb them to the hot water line.

[PNWHiker]

It may be a bug in Rheem's programming (either the app or the unit), but when I've had my Rheem set to Heat Pump mode I have seen the elements come on after heavy use like from a shower. I have never seen the elements activate when in Energy Saver mode. YMMV.

It's my understanding that Rheem hybrid heaters will use resistance heating if the heat pump is not able to bring up the temperature to the set point in a given amount of time. It's possible that you have a dud compressor, that your water is exceptionally cold, or that the water heater is in a very cold environment. My Rheem proterra is in a basement that ranges from 55-65 F all year.

When it's in Energy Saver mode I have no complaints and it works just fine. I've never seen the element get used in that mode, only the compressor. I've tried Heat Pump mode to see if I could drive more overall efficiency, but the times I've tried it I have noticed it turning on the element, which was completely unexpected (I expect "Heat Pump" mode to *only* use the heat pump). The terminology in the app is certainly not overly clear as to what will actually happen in each mode.

[cmr79]

BTW - if you do have a dishwasher with only one water connection (like my family's Miele) and have a heat pump water heater, you should connect it to hot water to save some cents each time you run it.

AFAIK the vast majority of dishwashers only have one water inlet. In the U.S. we normally plumb them to the hot water line.

I realized after the fact that this was probably the case, as I can't imagine a reason to have a cold water intake on a dishwasher in the first place. Apparently they do exist, so there must be a reason...

[prioritarian]

It's my understanding that Rheem hybrid heaters will use resistance heating if the heat pump is not able to bring up the temperature to the set point in a given amount of time. It's possible that you have a dud compressor, that your water is exceptionally cold, or that the water heater is in a very cold environment. My Rheem proterra is in a basement that ranges from 55-65 F all year.

When it's in Energy Saver mode I have no complaints and it works just fine. I've never seen the element get used in that mode, only the compressor. I've tried Heat Pump mode to see if I could drive more overall efficiency, but the times I've tried it I have noticed it turning on the element, which was completely unexpected (I expect "Heat Pump" mode to *only* use the heat pump). The terminology in the app is certainly not overly clear as to what will actually happen in each mode.

I use mine in heatpump only mode and the resistive element never activates.

[qlogicnewb]

AFAIK the vast majority of dishwashers only have one water inlet. In the U.S. we normally plumb them to the hot water line.

I realized after the fact that this was probably the case, as I can't imagine a reason to have a cold water intake on a dishwasher in the first place. Apparently they do exist, so there must be a reason...

My US Bosch manual says to connect the dishwasher to cold water line. That makes sense if the dishwater uses little water and hot water line is long.

[yankees60]

When it's in Energy Saver mode I have no complaints and it works just fine. I've never seen the element get used in that mode, only the compressor. I've tried Heat Pump mode to see if I could drive more overall efficiency, but the times I've tried it I have noticed it turning on the element, which was completely unexpected (I expect "Heat Pump" mode to *only* use the heat pump). The terminology in the app is certainly not overly clear as to what will actually happen in each mode.

I use mine in heatpump only mode and the resistive element never activates.

How would one know if the resistive element activates during heat pump mode?

[Valuethinker]

Do American appliances connect to a hot tap? In the UK, pretty much 100% connect to a cold water line. It's why dropping the wash temperature from 40 degrees C to the now-recommended by clothing manufacturers, 30 degrees C, makes such a difference to the energy used in a washing machine (ie the input water is about 10-12C say).

Obviously, for the heat pump water heater ... it is getting fed by cold ground water. As I write this ... probably at its coldest all year.

In the nearly 43 years I've owned my house I've never used anything but cold water in the washing machine. I do have the option of putting hot water into it.

My understanding is our ground water (from the London municipal supply system) is a pretty constant 10-12 degrees C (ie 50-55 F) all year around. Pipe is about 18 inches below the ground. So summer/ winter should not have that much impact (the water already in the pipes in the house will be hotter or colder depending on season).