Heat Pump Hot Water Heater in Basement

[stcm]

Hi Folks,

I noticed an old thread where people started commenting on heat pump hot water heaters in basement...I'm hoping to get input now that you've had them installed for a while...(PelletKing has a hybrid in his northern CT basement, that's very interesting to me).

I live in northern MA and my basement gets down into the mid 40's during the deep winter months. I'm looking to replace my leaking boiler SuperStore water heater with a heat pump hot water heater. I need to go with non-hybrid version since I don't have the electric panel capacity to run 220V for a hybrid. Any thoughts on if I'll be ok with hot water in the winter months? I think it should be fine and worst case I can run an electric radiant heater next to the tank down there if I get in a real pinch. (House was built in 2002 and basement is about 1,200 sqft, unfinished, wide open, if that's of help.)

Thanks for any help/insight you can provide on your experiences using heat pump-only hot water heater in basement during New England winter months.

 

[woodgeek]

Not sure what you mean by 'hybrid/non-hybrid'. All HPWHs come with a heating element installed, which kicks in if the air temp gets too low (like 45°F or so). The HP features usually uses a lot less amps than the element.

Are you asking if you can install a HPWH with the element disabled?

If your panel is full, you can get almost certainly make room by putting two 120V circuits on a 'tandem' two-circuit breaker that that takes a single slot... and be good to go. What brand panel do you have, and how big is the main breaker (100 or 200A)?

 

[EbS-P]

You are referring to the 120v HPHWHs I assume.

For how many days is it 40 degrees down there? How big is your family?

I have run my 80 gallon unit in heatpump only mode when the basement was about 55. It took a long line time to reheat. We are a big family but. But a load of dishes a careless kid in the tub and one soaker tub will run it out of hot water and it will. Take 2+ hours to get enough for a shower.

My gut says if you it’s more than a month in the 40s and your family doesn’t want a bathing schedule or use the delay on the dishwasher you will not be happy.

That said I would really consider what it would take to upgrade your electric capacity. Any EV really needs 240v (but only) 20amps for 100 miles a day). A mini split heatpump will need 240v. There will be rebates and or tax credits available to upgrade electric service starting next year. But I don’t have any details.

And let’s verify what your main service capacity is? 100A or more and what major electric appliances are on it.

To summarize. I’m not sure I would with my unit any family but yours may be different

Check these out these require 15 amp dedicated circuit. They have another one that has smaller capacity and can share the circuit with other things. https://rmc-cdn.s3.amazonaws.com/me..._Plug-in-Heat-Pump-Dedicated-Circuit_0610.pdf

If you could insulated enough to keep it 55 degrees I would feel better about it.

 

[stcm]

Both extremely helpful pieces of feedback, thank you! I was considering just the 120V HPHWH which does not have the heating element backup (because it's just my wife and me living here, but it does get that cold for a few months out of the year and I do need to consider resale value of buying a hybrid unit). HOWEVER, I didn't realize that the tandem 120V breakers existed. It's a 200A Square D panel and I'm just out of space for breakers..installing a couple of those tandem breakers becomes a game changer for the short term until I upgrade the system for expected EV/batteries within the next two years. Thank you for excellent feedback...I'll install a couple of tandems to free up space for a 220V breaker for a hybrid unit.

I do still welcome any other feedback from folks if they are finding they can run in heat pump mode only in mid 40 degree basement (with two people who aren't crazy water consumers)...was planning to get a 60 gallon unit. Thanks for the help!

 

[woodgeek]

In the end, its up to the engineering of the unit. The hybrid unit I have doesn't have a defrost capability, so it shuts off the HP when the air temp reaches 40 or 45 °F or thereabouts (in my attached, unheated garage).

Above that, it takes longer to recover, but with a couple adults, its unlikely to be a big problem.

 

[EbS-P]

Both extremely helpful pieces of feedback, thank you! I was considering just the 120V HPHWH which does not have the heating element backup (because it's just my wife and me living here, but it does get that cold for a few months out of the year and I do need to consider resale value of buying a hybrid unit). HOWEVER, I didn't realize that the tandem 120V breakers existed. It's a 200A Square D panel and I'm just out of space for breakers..installing a couple of those tandem breakers becomes a game changer for the short term until I upgrade the system for expected EV/batteries within the next two years. Thank you for excellent feedback...I'll install a couple of tandems to free up space for a 220V breaker for a hybrid unit.

I do still welcome any other feedback from folks if they are finding they can run in heat pump mode only in mid 40 degree basement (with two people who aren't crazy water consumers)...was planning to get a 60 gallon unit. Thanks for the help!

If you have 200 amp service i would see about the tandem breakers. To free up space in my sub panel for a car charger I was able to swap the 15 amp circuit’s (2) that the bedroom were on with an AFCI 15 Amp tandem. Now all my bedrooms are afci protected. Zero nuisance trips in 8 months. Could not find a similar product in the square D line. I have a Siemens sub panel .

Back to the question about cold environments. With only two people it might be possible but definitely running on the edge of being to cold. One can install a ducting kit. And choose where it draws air from and exhaust too. I have a Thread here. Either way you consider that it will cool the space. It is notice in the winter in our basement when we don’t run the heatpump and are just heating with the upstairs wood stove. And the warmer the intake Marie the higher the efficiency is.

Heat pump water heater ducting question?

Hi am having an 80 gallon heat pump water heater installed in the basement. It will be in a mechanical space that is 15’x2’. One long and one short wall are crawl space walls while the other long wall is half bathroom wall and half back of closet. The Bedroom room then is about 15x15...

www.hearth.com

 

[sloeffle]

I live in northern MA and my basement gets down into the mid 40's during the deep winter months. I'm looking to replace my leaking boiler SuperStore water heater with a heat pump hot water heater. I need to go with non-hybrid version since I don't have the electric panel capacity to run 220V for a hybrid. Any thoughts on if I'll be ok with hot water in the winter months? I think it should be fine and worst case I can run an electric radiant heater next to the tank down there if I get in a real pinch. (House was built in 2002 and basement is about 1,200 sqft, unfinished, wide open, if that's of help.)

Have you thought about insulating the basement ? Is there any insulation around the rim joist or on the walls. I'm in Ohio and my basement stays in the 60's year round and I have a big inefficient patio door also. The walls are insulated and my rim joist is spray foamed down two blocks.

Switched to a HPHW a number of years ago. When the ex and kid were here full time it saved me about $50 over a conventional electric hot water heater. Well worth the investment at that time.

 

[stcm]

This all makes good sense, thanks for the helpful feedback, all.

 

[Rob711]

June of 2021 I installed a Rheem 80 gallon HPWH in my unfinished basement, it’s below my living room. With a empty house, no tv on, you can notice it running but It’s a low white noise. I’m thinking our winters are similar Last year when it was really cold I saw 46 in the basement, it was still running in the heat pump mode. I’ve since replaced the basement windows, insulated the sil with spray foam, we plan to finish the basement sooner than later.
My wife and 3 soon to be teen daughters have yet to run out of hot water so that’s pretty good. I went wth 80 gallons due to the longer recovery I read about. I’ve always had gas or oil hot water heaters so far I’m happy with the heater.
I’ve also framed a room around the hot water heater and gas furnace, if you were normal and didn’t belong to a wood stove forum I’m sure the wasted heat off the gas furnace would lessen the time the heat pump runs in the winter, but here we are.

 

[Highbeam]

I have a family of four with two teen daughters and a 40 gallon electric resistance tank water heater and unmetered well water. We have never run out of hot water. I think modern fixtures have really helped reduce the amount of “tank” that homes need these days.

 

[stcm]

Excellent, the rim joists are spray foam insulated and basement ceiling insulated, but not my basement walls...I'm going to move forward with a 60-80 gallon HPHWH (hybrid using the tandem breakers to free up some panel space) and excited to move away from the oil/SuperStore setup (which is only lifetime warrantied to the original purchaser).

 

[EbS-P]

Excellent, the rim joists are spray foam insulated and basement ceiling insulated, but not my basement walls...I'm going to move forward with a 60-80 gallon HPHWH (hybrid using the tandem breakers to free up some panel space) and excited to move away from the oil/SuperStore setup (which is only lifetime warrantied to the original purchaser).

Have you researched a 2022 vs 2023 purchase? Fed tax credits may be different but I don’t know.

 

[stcm]

Have you researched a 2022 vs 2023 purchase? Fed tax credits may be different but I don’t know.

Thanks for asking, it does not appear we'll qualify in 2023 with income-bracket limitations on tax credits.

 

[Ashful]

A few comments about what's already been said:

1. You cannot just (legally) put tandem breakers in any panel. While they'll fit (and it's done all the time), many panels are not labeled for them, or the circuit count that can be achieved with tandems. Check your panel literature, Google is your friend. It's sometimes better/easier to just install a second panel tagged off the main with a 100A breaker pair. I have five panels in this house, with a sixth in my shop across the driveway.

2. I'm surprised your basement gets as cold as 40F with a boiler running! My little 350 sq.ft. boiler room must hold damn near 85F all winter, even if the rest of the basement is 20-30F cooler. If removing the boiler, your utility room will get substantially colder than it already is, and then a HPWH will extract even more heat from that new low over the course of the season. Put otherwise, if you're at 40F now, you'd almost certainly be into frozen pipe territory with these two changes.

(Note: Yes I know that the HP won't be running below ~45F, but it will when warmer, which will lower average temperature in the basement, resulting in lower interior "lows" when it gets truly cold out.)

3. With only two users, I'm rather doubtful of any true advantage of installing a HPWH over just repairing or replacing the boilermate, especially in a cold basement, where efficiency of the HPWH will be minimized. Have you priced install and operating costs of both options?

 

[woodgeek]

@Ashful makes good points, and the OP mentioning that the basement ceiling is insulated... ugh.

People often do that bc they complain that the first floor floor is cold. And it creates a large unconditioned space that is less useful and requires dehumidification in the summer. Odd that the rim joists are sealed, but the side walls not insulated, but I guess that helps with the aforementioned humidity. Yeah... we could worry about frozen pipes, but I assume that none are near the side-walls, or in drafty places, or OP would already have frozen pipes.

I disagree about the boilermate. The parasitic/cycling losses on even a cold start boiler are large, and provide useless heat in the summer season. As usage goes down, these losses could easily exceed the actual BTUs being delivered out a tap. For example, my neighbors next door in an identical house run their central AC whenever the outdoor temp gets much above 65°F, while mine doesn't work that way. They still have an oil boiler heating their house all summer long (for HW). My house used to have the same problem.

In reality, a conventional HPWH will switch to elements at around 40-45°F, so it will not directly cause a pipe freeze by pulling down the temp. But the loss of the boiler heat to the basement is a concern. One could put a space heater down there with a stat set to 40 degrees or something as cheap insurance... but at MA electric rates, that will eat into the savings.

I would insulate the basement walls as part of this project. That should suffice to keep it above freezing, even with the ceiling insulation IMO. That would also keep the temps there more moderate, which might be considered a side benefit, unless the OP is already hanging sides of beef down there. If the warmer basement is seen as a positive, some ceiling insulation could be easily torn down, where a cold floor or other surface would not be problematic.

I will note that I had a boiler room that got 'too cold' when I removed the boiler (in 2012). It was an interior room, but the exterior wall was intentionally left uninsulated (in 1960) and no heating zones were placed there ofc. Not a big deal, but I ended up insulating the wall and adding a branch duct of my central HVAC, bc it was used as a laundry room, and was adjacent to a bathroom that was getting chilly too. Note: the HPWH was not put in the boiler room, but an adjacent unheated garage.

 

[stcm]

@Ashful makes good points, and the OP mentioning that the basement ceiling is insulated... ugh.

People often do that bc they complain that the first floor floor is cold. And it creates a large unconditioned space that is less useful and requires dehumidification in the summer. Odd that the rim joists are sealed, but the side walls not insulated, but I guess that helps with the aforementioned humidity. Yeah... we could worry about frozen pipes, but I assume that none are near the side-walls, or in drafty places, or OP would already have frozen pipes.

I disagree about the boilermate. The parasitic/cycling losses on even a cold start boiler are large, and provide useless heat in the summer season. As usage goes down, these losses could easily exceed the actual BTUs being delivered out a tap. For example, my neighbors next door in an identical house run their central AC whenever the outdoor temp gets much above 65°F, while mine doesn't work that way. They still have an oil boiler heating their house all summer long (for HW). My house used to have the same problem.

In reality, a conventional HPWH will switch to elements at around 40-45°F, so it will not directly cause a pipe freeze by pulling down the temp. But the loss of the boiler heat to the basement is a concern. One could put a space heater down there with a stat set to 40 degrees or something as cheap insurance... but at MA electric rates, that will eat into the savings.

I would insulate the basement walls as part of this project. That should suffice to keep it above freezing, even with the ceiling insulation IMO. That would also keep the temps there more moderate, which might be considered a side benefit, unless the OP is already hanging sides of beef down there. If the warmer basement is seen as a positive, some ceiling insulation could be easily torn down, where a cold floor or other surface would not be problematic.

I will note that I had a boiler room that got 'too cold' when I removed the boiler (in 2012). It was an interior room, but the exterior wall was intentionally left uninsulated (in 1960) and no heating zones were placed there ofc. Not a big deal, but I ended up insulating the wall and adding a branch duct of my central HVAC, bc it was used as a laundry room, and was adjacent to a bathroom that was getting chilly too. Note: the HPWH was not put in the boiler room, but an adjacent unheated garage.

Yeah, the boiler definitely has to cycle for fairly long duration on occasion just to heat the hot water tank. Pricing of a hybrid hphwh seems within ~$100 of a new SuperStore of same capacity plus I have excess solar capacity right now to use for the hphwh. The basement is warmer most months as well, just a handful of winter months that are colder. Interesting angle with insulating the walls...I was thinking it was better to not have insulated since it will effectively act as geothermal...hphwh might pull the temp down when running, but it will restore to mid-40's (during coldest winter months) by regulating back to the below-ground temp through the basement walls/floor.

Either way I'm looking forward to moving to electric hphwh given solar capacity, noisy Tjerlund side shot exhaust (all it takes is a little soot on the fan blades to get it slightly out of balance and make noise...awful design) and volatile oil prices. Thanks for all of the great help/insight.

 

[Ashful]

Of course woodgeek is probably right, I'll defer to him on almost any point regarding energy and home utilities, but I would put my thumb on the scale of two points:

1. My boilermate does not cause the boiler to cycle when we are not using hot water. The tank is very well insulated, and is still holding hot water as much as 2 days after shutting the boiler off. So any argument about storage losses needs to be taken with a very serious grain of salt. Of course there is storage loss, but only in theory, the actual numbers must be so low as to really not factor into any useful debate.

2. I agree that running a boiler for hot water puts useless heat into the house, and this may make your AC run more. But our cooling costs even in PA are just a small fraction of our heating costs, and the OP is 1000 miles north of us! So, yes... a boilermate will cause an added cooling expense in summer, but I'd bet that this very small added cost is still much smaller than the differential spent on a HPWH, when all install and operating costs are properly accounted.

 

[EbS-P]

With solar oil to electric water heater is a no brainer. I doubt the exhaust gets any below 40-45 degrees. I’ve had similar thoughts about insulation on walls. Down here but with a finished basement with unfinished walls it’s the summer where I get the benefit.

Remember you can duct it intake and or exhaust. With wood heat it’s effectively heating with wood.

 

[begreen]

Note: the HPWH was not put in the boiler room, but an adjacent unheated garage.

Did you add an insulation wrap to the tank to reduce heat loss in cold winter weather?

 

[woodgeek]

Did you add an insulation wrap to the tank to reduce heat loss in cold winter weather?

Its a tuck under garage, only getting down to 40°F in very cold weather. And modern tanks have very thick insulation.

 

[DBoon]

If you don't have room for a 240V breaker in your 200A panel, why not install a 50A subpanel fed from your 200A panel and put the 240V breaker in the subpanel?

 

[stcm]

If you don't have room for a 240V breaker in your 200A panel, why not install a 50A subpanel fed from your 200A panel and put the 240V breaker in the subpanel?

Yeah, it's just more $$ than I wanted to spend short term (in our town you're not allowed to do your own electrical), but I recognize that's an option, thanks.

 

[Ashful]

Yeah, it's just more $$ than I wanted to spend short term (in our town you're not allowed to do your own electrical), but I recognize that's an option, thanks.

Not allowed to work on your own house? This town is in America?

 

[Where2]

Not allowed to work on electrical in your own house? This town is in America?

When I DIY installed my PV array, on the day of my final inspections for structural and electrical, the AHJ inspectors both asked me if I could teach the local licensed installers how to do work as good as my setup. The told me some horror stories about things they've been called to inspect that were nowhere near meeting NEC.

Fast forward 6 years, I needed to swap out the main disconnect breaker and main electrical panel at my parents house down the street. I was told: because that house is not my primary residence, I'd have to hire a licensed electrician to do the electrical work for me. I'm still sorting out what breaker controls what in that house...

I look forward to working on my other house where literally all the AHJ cares about is plumbing being up to code...

 

[Ashful]

I needed to swap out the main disconnect breaker and main electrical panel at my parents house down the street. I was told: because that house is not my primary residence, I'd have to hire a licensed electrician to do the electrical work for me. I'm still sorting out what breaker controls what in that house...

How does any authority know that you plan to, or even if you did, swap a breaker panel on your own? Does your local Lowes Depot require proof of license at point of purchase?

If I need to replace a breaker panel, I buy one and do it. Never even thought to call any inspector to ask for permission or inspection, any more than I’d think to ask them to come evaluate my wood splitting skills.