A.O. Smith Heat Pump Water Heater

[Dick in Wisconsin]

We are remodeling, reroofing, and adding to our house. We currently have an NG water heater with a chimney, only device that uses a chimney. I'd like to eliminate the chimney. We was thinking about going to a high efficiency water heater with the PVC pipe in and out the side of the house and eliminate the chimney. Went to Green Bay new home showcase on Sunday and saw a number of houses with A.O. Smith heat pump water heaters.

We have an open loop (pump and dump) WaterFurnace ground water heat pump with a superdeheater that pre-heats water ahead of the water heater that I'd like to continue using. Our basement is kinda cool. I'm assuming that the Smith HP water heater will give me "free" dehumidifying in the basement but in the winter the basement will be colder as the Smith HP water heater pulls heat out of the basement to heat the water with. Having lived with heat pumps for close to 70 years, I understand the process, physics, and advantages of them over the alternatives.

What has the experience of the GJF members been with the A.O. Smith Heat Pump Water Heaters? Is A.O. Smith the best? It there a better one? Does the Smith HP water heater have a quality compressor and components?

Since I pump and dump water now, is there a source of a GWHP water heater? Thanks!

 

[u3b3rg33k]

We are remodeling, reroofing, and adding to our house. We currently have an NG water heater with a chimney, only device that uses a chimney. I'd like to eliminate the chimney. We was thinking about going to a high efficiency water heater with the PVC pipe in and out the side of the house and eliminate the chimney. Went to Green Bay new home showcase on Sunday and saw a number of houses with A.O. Smith heat pump water heaters.

We have an open loop (pump and dump) WaterFurnace ground water heat pump with a superdeheater that pre-heats water ahead of the water heater that I'd like to continue using. Our basement is kinda cool. I'm assuming that the Smith HP water heater will give me "free" dehumidifying in the basement but in the winter the basement will be colder as the Smith HP water heater pulls heat out of the basement to heat the water with. Having lived with heat pumps for close to 70 years, I understand the process, physics, and advantages of them over the alternatives.

What has the experience of the GJF members been with the A.O. Smith Heat Pump Water Heaters? Is A.O. Smith the best? It there a better one? Does the Smith HP water heater have a quality compressor and components?

Since I pump and dump water now, is there a source of a GWHP water heater? Thanks!

Rheem has come out with plug-in, 120V units in both 4kBTU and 12kBTU compressor output capacities. either one should be fine with pre-heated water from your geo. I'm unaware of any standalone units sold as water-source HPWHs, but I don't see why you couldn't use another WTW geo unit as a water heater, just add an appropriately sized double-wall HX.

 

[larry4406]

No experience with the AO Smith but we do have a Rheem 80G hybrid heat pump WH.

It has been working great. It’s in our basement. We are 100 electric heat pump for AC/Heat. So the heat the WH steals from the basement the main heat pump adds back. Still net savings $30-50/month compared to the old resistance heater WH version.

I do know that Rheem frowns upon hot water recirc systems with their hybrid unit. Something to do with their control algorithm and the now higher “cold water” inlet temperature. So much so that their tech bulletin says if you want recirc, then turn the hybrid mode off!

Your geo system that preheats the water would likely give the Rheem same issues.

 

[u3b3rg33k]

No experience with the AO Smith but we do have a Rheem 80G hybrid heat pump WH.

It has been working great. It’s in our basement. We are 100 electric heat pump for AC/Heat. So the heat the WH steals from the basement the main heat pump adds back. Still net savings $30-50/month compared to the old resistance heater WH version.

I do know that Rheem frowns upon hot water recirc systems with their hybrid unit. Something to do with their control algorithm and the now higher “cold water” inlet temperature. So much so that their tech bulletin says if you want recirc, then turn the hybrid mode off!

Your geo system that preheats the water would likely give the Rheem same issues.

imho any HWPH that has pure electric modes is a joke, especially if the default operating mode prefers the resistance heaters, or the spec sheet only gives capacity data based on resistance heating. those modes throw all the ROI right out the window.

who needs a HPWH with 1500BTU of compressor and 15000BTU of backup heat? that's dumb. the 12kBTU 120V rheem makes sense. that's a 1 ton window rattler, which runs on 120V just fine.

 

[American Locomotive]

Hybrid water heaters typically have a ~4000 BTU/hr heat pump, and even in hybrid mode will do the majority of their heating using the heat pump. The pure electric modes are simply for backup.

The reason they're not all 12,000 BTU/hr units is two fold:
1) The larger condensing units tend to be less efficient. The 12k BTU unit has a noticeably lower COP than the others.
2) 12,000 BTU/hr really limits where you can put it. The standard 4,000 BTU/hr units will operate comfortably with a moderate amount of venting in even quite small areas. A 12,000 BTU unit will pull down a space's temperature very quickly if there isn't a lot of available air flow or heat.

 

[u3b3rg33k]

the problem with the 4k BTU heaters is if you have a house where you need a reheat time shorter than 10 hours, you're going to have to either enjoy cold water, or put it in a mode that uses the backup heat. I'd rather give up a little bit of efficiency and have hot water, than have something super efficient that takes all day to reheat. the 12k plug in model is functionally equivalent in recovery time to a 240V standard electric unit, but costs 1/3 as much to run. you can always duct it as well.

 

[fredws]

When you say the desuperheater preheats the water ahead of the water heater, do you have a buffer tank that is in front of your water heater?
In regards to geo water heater, WaterFurnace, as well as other brands, though I would highly recommend staying with WaterFurnace, makes a water-to-water unit that would heat your water. They also make a unit called Synergy 3-D that will heat your water as well as heat your air for your house. However, unless your geothermal unit is really old, and on its way out, I would not recommend going this route.
I will wait for a response to the original question before I go any further.

 

[Mzungu]

So to actually answer your question regarding AO Smith HPWHs. I live in central interior British Columbia. I have owned an 80 gallon unit for more than 6 years. Runs 100% on efficiency mode (no elements) . Family of four with a wife who loves the hottest showers and baths imaginable. The heater is in our basement as well, which doesn't really effect anything as we burn wood in the winter. I clean the intake filter once every two months, I cleaned the condenser fine for the first time this summer, and I replaced the anode this summer as well.

 

[Chris Brecht]

I have installed three different ones at different houses. The first two worked great the third one is a year old and has started having issues. The error code says the heat pump is the issue however if you cycle the power it works fine for a few weeks then has issues again. I think it is the circuit board. AO Smith wants me to have an HVAC person come out and test the heat pump. I have talked to a buddy that does that for a living and he said he wouldn't touch it. He agrees it sounds like the circuit board.

 

[American Locomotive]

the problem with the 4k BTU heaters is if you have a house where you need a reheat time shorter than 10 hours, you're going to have to either enjoy cold water, or put it in a mode that uses the backup heat. I'd rather give up a little bit of efficiency and have hot water, than have something super efficient that takes all day to reheat. the 12k plug in model is functionally equivalent in recovery time to a 240V standard electric unit, but costs 1/3 as much to run. you can always duct it as well.

I get that, but it also depends on how much hot water you use. We have a 50 gallon tank, with the water set to 130*F. There's enough hot water for three people to take showers in the morning without a perceptible loss of hot water. Usually 4-5 hours later it has satisfied. A larger household could get a 60 or 80 gallon unit instead.

If you completely flatten the tank, yea, it will take a while to heat back up.

 

[u3b3rg33k]

I think the COP numbers are worse at the higher temps, but a lot of the literature is what I would call deceptive advertising. I'm looking forward (or not) to seeing pricing on the 120V models.

I'm also a bit miffed (still) by the price hikes on the 4k models that seemed to appear around the time the heavier incentives came out. must be nice in a state with big incentives, but here there's basically nothing.

 

[HoosierBuddy]

If I only had power available and no natural gas, I'd be all over a heat pump water heater. But since OP has natural gas?

Just comparing numbers on AO Smith's site....

Their 80 gallon "hybrid" unit list an annual energy cost of "as low as $173"....which I assume is running only in heat pump mode.
Cost is $2700.

I compared it to a random 40 gallon natural gas power vent water heater which claims $266 annual energy costs with a price of $1300 (which seems astronomical to me...but I haven't had to buy a water heater in several years).

I know energy costs are all over the map...but for arguments sake, let's use those numbers.

Annual savings $93
Up front extra cost $1400
Straight payback 15 years

I'd go with natural gas. Course I work for a gas company, so there's that too.

 

[nadogail]

IMHO, A O Smith has a good reputation. I don't presently own any of their products and have no connection wirh th company.

 

[mike93lx]

If I only had power available and no natural gas, I'd be all over a heat pump water heater. But since OP has natural gas?

Just comparing numbers on AO Smith's site....

Their 80 gallon "hybrid" unit list an annual energy cost of "as low as $173"....which I assume is running only in heat pump mode.
Cost is $2700.

I compared it to a random 40 gallon natural gas power vent water heater which claims $266 annual energy costs with a price of $1300 (which seems astronomical to me...but I haven't had to buy a water heater in several years).

I know energy costs are all over the map...but for arguments sake, let's use those numbers.

Annual savings $93
Up front extra cost $1400
Straight payback 15 years

I'd go with natural gas. Course I work for a gas company, so there's that too.

I have natural gas but am installing heat pumps for my hvac and just put in a heat pump for my pool, with a goal of reducing natural gas usage. If it costs a little more, so be it.

I have a gas water heater that is only a year old, so it's in no danger of needing replacement but when it does, I bet it will be a heat pump.

 

[American Locomotive]

If I only had power available and no natural gas, I'd be all over a heat pump water heater. But since OP has natural gas?

Just comparing numbers on AO Smith's site....

Their 80 gallon "hybrid" unit list an annual energy cost of "as low as $173"....which I assume is running only in heat pump mode.
Cost is $2700.

I compared it to a random 40 gallon natural gas power vent water heater which claims $266 annual energy costs with a price of $1300 (which seems astronomical to me...but I haven't had to buy a water heater in several years).

I know energy costs are all over the map...but for arguments sake, let's use those numbers.

Annual savings $93
Up front extra cost $1400
Straight payback 15 years

I'd go with natural gas. Course I work for a gas company, so there's that too.

You could also go much cheaper - for example, the Rheem 50 gallon is about $1700, and we haven't had a problem with hot water for 4 people. It also depends on your electric rates too. For example, in New England, my electricity rates are about double most of the U.S., so pay back is much faster. Mine actually paid for itself compared to a pure electric heater in less than a year.

 

[HoosierBuddy]

I have natural gas but am installing heat pumps for my hvac and just put in a heat pump for my pool, with a goal of reducing natural gas usage. If it costs a little more, so be it.

I have a gas water heater that is only a year old, so it's in no danger of needing replacement but when it does, I bet it will be a heat pump.

That's a good way to increase natural gas usage and coal usage as coal and natural gas make up over 50% of the fuel for power generation and generation/grid is about 33% efficient when comparing energy in at the power plant to energy out at your meter.

 

[u3b3rg33k]

That's a good way to increase natural gas usage and coal usage as coal and natural gas make up over 50% of the fuel for power generation and generation/grid is about 33% efficient when comparing energy in at the power plant to energy out at your meter.

that's been proven to be incorrect. heat pump run on a combined cycle NG grid = more efficient than a burning NG locally in a condensing boiler/furnace.

Even the lazy math, assuming your 33% is correct shows your error. COP 3 * 33% = 99%. condensing furnace =94-96%.

 

[mike93lx]

That's a good way to increase natural gas usage and coal usage as coal and natural gas make up over 50% of the fuel for power generation and generation/grid is about 33% efficient when comparing energy in at the power plant to energy out at your meter.

Awesome thanks.

Still moving forward with it

 

[mike93lx]

that's been proven to be incorrect. heat pump run on a combined cycle NG grid = more efficient than a burning NG locally in a condensing boiler/furnace.

Even the lazy math, assuming your 33% is correct shows your error. COP 3 * 33% = 99%. condensing furnace =94-96%.

I'm using the HP's to supplement 80% furnaces, so even better.

There is too much heat naturally available in my region to not take advantage of

 

[u3b3rg33k]

I'm using the HP's to supplement 80% furnaces, so even better.

There is too much heat naturally available in my region to not take advantage of

if the 80% is a backup to a heatpump in a warm climate, there's probably no ROI on replacing a good 80% with a condensing unit that'll never run. kinda like replacing a prius with a newer prius that gets better MPG. the ROI on 50MPG vs 45MPG is... long.

 

[mike93lx]

if the 80% is a backup to a heatpump in a warm climate, there's probably no ROI on replacing a good 80% with a condensing unit that'll never run. kinda like replacing a prius with a newer prius that gets better MPG. the ROI on 50MPG vs 45MPG is... long.

That's where I landed. The major issue for me was the change in drainage/venting. It was going to be a real pain and cause a ton of work

 

[jcarapet]

Adding my 2 cents as a recently former heat pump water heater owner. AO Smith is fine from what I've read, but Rheem are the real winners. No issues in 9 months before i sold previous house, and noticed a $20-$30 drop on average for electric bill. (Rheem proterra 65 gallon vs. 2002 40 gallon GE)

Like all electric HW heaters require maintenance but relatively easy. i checked the air filter ever couple months in a dusty garage but never had to clean out anything.

I would imagine AO smith is just fine if less reliable than Rheem. The overall mechanics are sound and just make sure you have enough ventilation. whenever my current AO Smith dies in new house I will be replacing with heat pump.

 

[justler]

I have a Rheem Pro Terra 80gal HPWH.

With a three person household (Two adults and one toddler) we use about 5-6kwh/day on heat-pump only mode.
Showers are morning and evening and are long (20 minutes or longer).
We cycle the entire tank probably 1-2 times each day.
Takes probably 35-40 mins to run out of water completely when at 130F.

I run it at 120F, then bump to 130F about 2 hours before shower time evening and morning (It's on a schedule in the app).

Someone else mentioned running a recirc pump with HPWH being an issue. I have a Grundfos recirc pump that I run however it is tied to some home automation and a motion sensor (When I enter the bathroom first thing in the morning, the motion sensor is triggered, turns on the pump for 1.5 mins then turns off. Same for shower hours in the evening).

The reason that a recirc pump on HPWHs is bad isn't due to the heater's algorithm, it's because you're dumping a cold load into the tank on a consistent basis depending on the recirc pump mode. In my scenario it's negligible because it's a few gallons once or twice a day. The other two common recirc methods are much worse:

1) If you are constantly running a recirc pump, it's basically radiant heat running through the water lines all the time and dumping the heat in your water into the house.
2) If you run the pump based on temperature, every time the return line hits say 110F, it pumps the the cooler water back into the tank and replaces what's in the lines with fresh hot water.
3) Grundfos also has another mode where it "learns" your habits which results in less recirc cycling.

In a recirc system some of this is mitigated by insulating the hot water lines, including the recirc line in your house.

The bottom line is that having recirc is going to increase your energy usage no matter what type of water heater you have, because depending on the mode, you could be constantly dumping cooler water into the tank than what's in it. Not really unique to HPWH, just means that in heat pump mode, you're going to run the heat pump a lot more.

Constant run recirc was doubling my kwh/day. Needless to say, I found a different solution. I at least have hot water immediately when we shower in the morning and evening, would be nice to have it for spot hand washing, but it's not worth the cost.

 

[rharman]

I'm (maybe) considering a heat pump water heater as a replacement for our 50gal AO Smith gas fired unit. It's coming up on 10 years old now.

We do have recirculating water - Grundfos pump that we turn on/off via an X-10 remote switch when we're going to shower or otherwise need hot water. All hot lines are insulated.

I have a 120v outlet adjacent to the WH location.
I see Rheem has this model - appears to be quite new:
ProTerra® Plug-in Heat Pump Water Heater with HydroBoost (120V Shared Circuit)

Anyone have any feedback on this? It would be in my unconditioned garage in the Los Angeles area of SoCal.

Thanks!

 

[rharman]

< bump >

No one?

If the shared circuit version sounds a bit cheesy, I do have a 240V/20A outlet in the garage for my old air compressor. It's on the left side of the back door and the WH is on the right side so there would be some relocation work. Might be a better solution?

Thanks!

 

[jlv03]

I don't think the shared circuit version sounds cheesy, but it does mean you are capped at how much heat you can transfer into the tank per hour.

A 50 gallon gas is going to have a pretty good recovery, which may mean you will have to upsize to an 80 gallon tank to get similar performance.

With your climate and water heater location, I think heat pump is a good solution. However I don't think I would rush into replacing a still functional water heater "just because".

 

[Firebrick43]

imho any HWPH that has pure electric modes is a joke, especially if the default operating mode prefers the resistance heaters, or the spec sheet only gives capacity data based on resistance heating. those modes throw all the ROI right out the window.

who needs a HPWH with 1500BTU of compressor and 15000BTU of backup heat? that's dumb. the 12kBTU 120V rheem makes sense. that's a 1 ton window rattler, which runs on 120V just fine.

Well I had one of the first GE HPWHs before they moved production to China. It worked great for 11 years on hp only. About 6 months ago the hp part failed. Sure was nice not to frantically run around to get it replaced. Just switched the control over to electric resistance.

Have a Rheem HPWHs in the garage I have to install

 

[rharman]

I don't think the shared circuit version sounds cheesy, but it does mean you are capped at how much heat you can transfer into the tank per hour.

A 50 gallon gas is going to have a pretty good recovery, which may mean you will have to upsize to an 80 gallon tank to get similar performance.

With your climate and water heater location, I think heat pump is a good solution. However I don't think I would rush into replacing a still functional water heater "just because".

Thanks for the feedback.

Yeah, I was concerned about the performance. Sounds like, with the shared circuit model, you don't have the auxiliary electrodes for heating or they're much smaller (I can't seem to find that reference right now).

I have seen mention of the need to upsize to offset the recovery time. I see the recovery GPH on the shared circuit is less than half of the dedicated circuit model. I recall them saying 65gal to replace a gas 50gal. They do push the benefit of the mixing valve and higher storage temp on the shared circuit model. My worry is that higher temp = higher wear.

Not rushing into it yet - it is a fairly new product after all. 10 years is maybe a bit early for replacement. I replace the anode every 2 years and regularly drain a few gallons. We did have a burner fail just after the 6 year warranty was up so I'm kind of factoring in that 6 year window again (we're 4 years into it now). Lowering our energy bill is a big plus. IRA rebates make it an enticing prospect as well.

So... not really "just because".

 

[Phuckin' Jim]

Figured you people might find this interesting:

If I lived where it was warm out, I'd consider doing this except I'd mount the outdoor unit indoors to help keep the house cool.
And I'd use one of the $425 usd mini splits.