Dual Heat Pumps on LI?

[NYR56]

I've been looking into installing a pool heater after using our pool for the first time last year. It's ~45-50K gallons and gets nearly full sun during the day on Long Island, NY. The pool is comfortable during the summer on sunny days (~78-80) but gets chilly after the sun sets. The curved L shape precludes a pool cover unfortunately. The pool company is pushing a 400k BTU natural gas heater, although I have to run a 200' gas line through the entire backyard. A few people have mentioned getting two heat pumps instead. I think that would get us up to around 280k BTU. We're not going in the pool unless it's at least 70 degrees outside, so I'm not trying to heat very cold water. Ideally we would keep the pool around 85 for the summer so we could go in after work and on weekends, which is why I'm leaning towards a heat pump. I assume I would need another electric line run to carry power for a dual heat pump situation, but that is likely much cheaper than a gas line. We don't have solar now but in ~10 years when the roof goes we'll get some panels.

Is this crazy compared to using a gas heater or will two heat pumps be able to accomplish what we're looking to do? Gas is only going to get more expensive, and heat pumps will continue to get more efficient, so I'd rather put in infrastructure for the future than regret I put in a gas line. It seems like running two heat pumps will still cost less than one gas heater. Appreciate any advice!

 

[1poolman1]

I've been looking into installing a pool heater after using our pool for the first time last year. It's ~45-50K gallons and gets nearly full sun during the day on Long Island, NY. The pool is comfortable during the summer on sunny days (~78-80) but gets chilly after the sun sets. The curved L shape precludes a pool cover unfortunately. The pool company is pushing a 400k BTU natural gas heater, although I have to run a 200' gas line through the entire backyard. A few people have mentioned getting two heat pumps instead. I think that would get us up to around 280k BTU. We're not going in the pool unless it's at least 70 degrees outside, so I'm not trying to heat very cold water. Ideally we would keep the pool around 85 for the summer so we could go in after work and on weekends, which is why I'm leaning towards a heat pump. I assume I would need another electric line run to carry power for a dual heat pump situation, but that is likely much cheaper than a gas line. We don't have solar now but in ~10 years when the roof goes we'll get some panels.

Is this crazy compared to using a gas heater or will two heat pumps be able to accomplish what we're looking to do? Gas is only going to get more expensive, and heat pumps will continue to get more efficient, so I'd rather put in infrastructure for the future than regret I put in a gas line. It seems like running two heat pumps will still cost less than one gas heater. Appreciate any advice!

This is based on you having a 50K gallon pool. That's huge for a residential pool.
How fast will you need the heat? A 400K BTU heater will add about .8 degrees an hour to that large a pool. Based on published data, that will cost about $8.00/hour for that heater.
Two heat pumps of 140K BTU, running parallelly will add about .7 degrees an hour if you can get the full rate BTUs, depending on how much heat is in the air. You would need at least a 100A service at the pool equipment just for two heat pumps. At your published electric rates and a rating of 7.2kw/hr. each that would be about $1.80 and hour.

 

[ajw22]

What is the electrical service to your main panel?

Older homes can have 100 amp service, and in many homes 200 amps is standard. Confirm you have adequate electrical capacity to add two heat pumps. HVAC systems, electric ovens, and EV charging can max out an older house's electrical system.

 

[JamesW]

Have you checked into rebates and tax credits.

Heat pumps can have rebates and tax credits and geothermal can qualify for incentives as well.

A 140,000 btu/hr heat pump is 11.7 tons and 2 is 23.3 tons.

If you can get a rebate of 1,500.00 per ton, then that is $35,000.00 credit.

• New York State Tax Credit 30% up to a maximum of $5,000.00.
• LIPA rebates up to $1,000.00 per unit.

Heat Pump Pool Heaters
$600 Rebate

Higher Rebates
The PSEG Long Island ground source heat pump rebate is $1,500 per heating ton (and $3,000 per heating ton for income eligible customer). In addition, we aligned our requirement to match ENERGY STAR®. A new qualifying three-ton ground source heat pump system rebate is $4,500 ($9,000 for income eligible).

Geothermal Energy - PSEG Long Island

Find out if geothermal is right for you – and learn about available rebates through the Cool Homes program.

www.psegliny.com

Residential Energy Efficiency Property Credit
Your energy efficient geothermal systems may also qualify for a federal tax credit.

The Bipartisan Budget Act of 2018 reinstated the residential renewable energy tax credit for renewable technology including ground source heat pumps.

You may claim a tax credit of 30% for qualifying systems, by using IRS Form 5695 .

Please consult with your tax accountant and your ground source heat pump installer for more details.

There is also a New York State income tax credit for 25% of the geothermal project cost, capped at a maximum credit of $5,000.

The details are in Section 606 (Credits against tax), Subsection (g-4) Geothermal energy systems credit.

 

[JamesW]

Geothermal Energy
Up to $2,000/ton in Rebates
Tap into the earth for your heating, cooling and hot water needs with a geothermal/ground source heat pump. In heating mode, these systems are four times as efficient as the most efficient fuel furnace or boiler. These pumps don't make new heat - they just extract the heat from the ground and amplify it. In cooling mode, these same units are twice as efficient as conventional air conditioning units.

Geothermal Energy - PSEG Long Island

Find out if geothermal is right for you – and learn about available rebates through the Cool Homes program.

www.psegliny.com

ENERGY STAR Rebates for Home Appliances - PSEG Long Island

Shopping for a washers, dryers, refrigerator or AC? Find rebates for ENERGY STAR certified products like central air, humidifiers, air purifiers & more.

www.psegliny.com

https://www.psegliny.com/saveenergyandmoney/greenenergy/-/media/46F86364A8844E5E9A5C267760F201F5.ashx

Rebates are capped at $25,000 (Market Rate) and $35,000 (Income Eligible Rate).

How much can I claim for new solar panels on my tax return?
You can receive a tax credit for a percentage of the cost (not including installation costs), which varies depending on when the system was/is placed in service.

30% for systems placed in service after December 31, 2016, and before January 1, 2020
26% for systems placed in service after December 31, 2019, and before January 1, 2022
30% for systems placed in service after December 31, 2021, and before January 1, 2033
26% for systems placed in service after December 31, 2032, and before January 1, 2034
22% for systems placed in service after December 31, 2033, and before January 1, 2035

Note that geothermal used exclusively for the pool might not qualify for rebates or tax incentives.

If you add solar, you can use that to power the heat pumps and save money.

You can add home geothermal and use the geothermal for pool heating as well.

You need to do a thorough investigation into all rebates and incentives to see what qualifies.

 

[JamesW]

Qualified geothermal heat pump property costs.

Qualified geothermal heat pump property costs are costs for qualified geothermal heat pump property installed on or in connection with your home located in the United States.

Qualified geothermal heat pump property is any equipment that uses the ground or ground water as a thermal energy source to heat your home or as a thermal
energy sink to cool your home.

To qualify for the credit, the geothermal heat pump property must meet the requirements of the Energy Star program that are in effect at the time of purchase.

The home doesn't have to be your main home.

https://www.irs.gov/pub/irs-pdf/i5695.pdf

Costs allocable to a swimming pool, hot tub, or any other energy storage medium that has a function other than the function of such storage don't qualify for the residential clean energy credit.

Instructions for Form 5695 (2024) | Internal Revenue Service

www.irs.gov

 

[NYR56]

Thanks for the replies. I'll have to look into all those credits James, had no idea about most of those. Not sure if they will apply or not to a swimming pool but worth a look.

We have 200amp service but I'm sure I'll need to run a 2nd line to the pool equipment if we are really doing 2 heaters. We are installing a few electric ovens in our kitchen (I think 3x18 amps), plus a couple AC units (18 amp x2 plus fan, and an inverter unit ~8amps), not sure if that would be a concern for hitting the overall limit although it seems we have plenty of capacity? I think our electric rates are closer to $0.15/KWH w/ delivery charges, but still that comparison to NG sounds pretty good. I don't need fast heat, just want it to be able to maintain it for the summer. One other option is installing one HP and seeing how it performs, hoping we don't have to run any electric for just one. I just tend to doubt that will be sufficient for the size pool we have. Main concern is overnight losses w/ no cover.

 

[nuttyp]

I love the idea of two heat pumps – I’ve been thinking about it for awhile, partly because I repaired one and now have a spare just sitting there unconnected The cost to run two should be nearly identical to the cost to run one – just faster with two, making it possible to recover the needed water temp at a reasonable time of the day after the nightly loss. Of course, in NY that will be a short season anyway, running only during seasons with 75degreesF highs for the daytime, as you say. But a longer season than with one heater. Also with two you get redundancy when one is broken.

I would plumb them in series, not parallel, thus avoiding the need to mess with flow diversion, inadequate flow, or a second pump. My former condo association runs a pair of heat pumps in series here in South FL, I imagine doing so is fairly common to speed up daily recovery from overnight losses in uncovered pools. With the two plumbed in series, I believe the pool service had one of them set 3 to 5 degrees warmer than the other, or maybe just a couple degrees different, I forget. They worked out some logical settings so that both ran to do the bulk of the work, then one of them fine tuned the temperature. One goal would be simply to keep them from cycling a lot, even though they have built in protection from true short cycling.

If those natural gas calculations are correct – wow, I had no idea electric pool heat was so much cheaper than natural gas. Many of us in South FL do not have natural gas service at all, so I never looked into it. Folks deploy large propane tanks sometimes, but that too is very pricey. I suspect you are correct that no tax credits could possibly apply to heating a pool, and I cannot think of any way to call electric heat pump pool heat “geothermal”. Still, worth a look as you say.

@1poolman1 offered some good math for your electric costs, but it would not surprise me if you wound up spending well over that $180 or even $360 per month, perhaps well over $400/month on just pool heat. I say that in part because you’ll be tempted to open the pool more when you can recover “quickly” (eg in 6 hours or so daily), also because you’ll be lucky to get 80% of the rated BTU when it’s cold out (see your heaters COP rating and BTU output spec at ambient temps) – especially in the mornings. And if you have a lot of surface area on a 50K gallon pool your overnight losses – uncovered – could be 10 degrees or more. Here I am in one of the warmest average US temp zones and I lose at least 5 degrees per night (uncovered, 16K gals) in March. If I lose more than 5 degrees on a colder or windier night, I turn off the pool heat because the recovery of those 5 degrees takes about 6 hours and therefore about $5-$6 per day at 15 cents per kwh. For me, that extra $150/month on the electric bill is about the max I’m willing to spend. It would, however, be nice to recover faster, at the same cost! Well, not truly the same cost because the pool would be heated for a larger portion of the day, and when it’s heated the loss rate and evaporation increases. Vicious circle In NY I might go with three heaters and a dome cover over the pool!

Of course, and as you and others noted, the service panel sizing and related breaker and/or subpanel sizings are critical. Best to get permitted and done by qualified electrician, inspected, etc. However, this residential load calculator can give you some good direction for main panels and subpanels – assuming you learn to use it carefully and properly. Electrical Load Calculations for Residential Service Panel - Online Load Calculator

Have fun! ... Joe

 

[Newdude]

@1poolman1 offered some good math for your electric costs, but it would not surprise me if you wound up spending well over that $180 or even $360 per month, perhaps well over $400/month on just pool heat.

Heat pumps are basically central ACs but reverse. Using the HP early or late in the season is like running an AC in July/Aug. Both bills skyrocket. Mid season, warming already warm water, the HP is like an AC in May /Sept and its barely turning on which makes it much more economical.

People often go HP for the regular season economics, but once they have it, try to extend the season. Thats where the buyers remorse comes in because it either can't perform the task, or the cost is high. Or both.

 

[nuttyp]

People often go HP for the regular season economics, but once they have it, try to extend the season. Thats where the buyers remorse comes in because it either can't perform the task, or the cost is high. Or both.

Hey @Newdude, I agree with your comparisons to AC in various seasons, but not so much in agreement with your latter points about extending the season. Most everyone I know with a Heat Pump uses it to extend the season. It's just a matter of degree, depending on your climate and how much you're willing to spend. Here in SW FL and many other Southern locales like Southern Texas, we don't need heat at all in the summer. So we use it to extend the season as I'm doing right now to swim comfortably (85F for us) in much of March, April and May, together with Sept & Oct. So I get 5 to 6 extra months of extended season as long as I'm not heating for more than about 6 hours per day - which for me equates to my max of $150/month. The degree of "extending" varies every month and every year, depending on weather patterns. In another example of variation, a guy down the street from me with a North facing pool and lots of shade trees might get several fewer weeks of "season extension" than I get, assuming other things being equal like wind blockage, pool size and surface area, and max expense tolerance like my $150 per month. Not to make such a fine point on all of it, but I do suspect, as perhaps you do, that @NYR56 will have that disappointing remorse given the NY location and perhaps only a minor increase in swimmable season - regardless of whether he uses one or two HP's - before the monthly heating cost becomes prohibitive. Especially because, as we noted earlier, the heat pumps are very inefficient at lower temps. And while trying to recover after a nightly low below, say, 60F, the pool continues to lose a lot of heat while the heater runs to try and catch up.

Based on the nightly average summer lows in NY (59-69F), I'm guessing you need the one or two heaters just to make the summer swimming comfy. I think if I lived there I would start with a single HP and determine if I think it's worth the extra cost to heat the pool more quickly and/or in order to extend the season by a few weeks. My guess anyway.

Another way to look at my situation would be to consider a second heater so that the pool recovered earlier in the day, so I could swim at noon instead of waiting for the 3PM recovery point (in March & Oct anyway). Still with the similar max spend of $150/month - via 3 hours of runtime on two heaters versus 6 hours on one heater. Fun to think about.

 

[Newdude]

but I do suspect, as perhaps you do, that @NYR56 will have that disappointing remorse given the NY location and perhaps only a minor increase in swimmable season - regardless of whether he uses one or two HP's - before the monthly heating cost becomes prohibitive.

Yes. Sorry. It was targeted advice for the northeast.

The HP up here entirely depended on the weather to comply. On warm years, it worked great extending the season. Last year it was crazy warm for crazy long and it would have been awesome for a reasonable cost.

On the average years it was so so, but i had to run it full time for fear of losing my warmth and not getting it back a week later if it stayed cool. It mostly worked, and only medium broke the bank.

On cool years, it struggled to produce more than i lost, or barely broke even, and cost a bloody fortune. I spent $100 or $200 a month th during the season and $300 or $400 for the cool/cold months. That's covered. I got the first 2 month bill at $600/$800 and raced out to buy a solar cover. Lol. Live and learn. It literally cut the bill in half.

Anywho, Its an ok gamble to take up here, providing one knows what they're getting into so they understand why some years are a bust. Particularly for @NYR56 who primarily wants it for the regular season up north.
If it works at all early/late, it's all gravy.

 

[NYR56]

Thanks all. I found an interesting price comparison on energy.gov that shows HP vs NG heater cost by city and desired temperature. In NY, at 82 deg it says a HP will cost $1660 to heat w/o a cover to 82, and $3250 w/ NG, for a 1000 sq ft pool. Unfortunately mine is 2000 sq feet, so I assume I would double those numbers. That's for May through Sept, which is pretty aggressive. I suppose when we have a heated pool though, we'll ultimately get spoiled and want it longer. That said, I really can't imagine going in when it's <70 outside. We enjoyed our pool last year without any heater but it was just a bit too chilly once the sun set for much of the season. Our main goal is to overcome that and make in comfortable for the summer. Any time we even thought about going in, the water was >70 deg, so I don't think we need a huge rise. That said, I can't really imagine spending $7k on gas, so if the HP is even slightly more efficient (and it sounds like it would be significantly more efficient), it seems like a much better way to go. Wild how much cheaper it is with a cover, I've thought about buying even just a rectangle cover to fit 2/3 of the pool, but it would still be a hassle and honestly ruin the look to some extent. Ultimately I'd feel guilty running the gas except for weekends, which kind of defeats the purpose, whereas w/ the HP I almost have to run it continuously, which would encourage us to take a dip more frequently. The website also mentions a HP will lose efficiency <50 deg of air temp, but again, I wouldn't even consider running it below that.

@nuttyp - Those charts really just make me want to live in Naples!

(Heat Pump Swimming Pool Heaters.)

HP.png

• NYR56
• Mar 12, 2025

NG.png

• NYR56
• Mar 12, 2025

 

[JamesW]

https://apps.raypak.com/wp-content/uploads/2019/02/RP-P-902-6-REV-C-Residential-Pool-Catalog.pdf

https://s3.amazonaws.com/AWSProd/sites/raypakcom/documents/RP-P-902-6.pdf

Calculators - Further Reading

www.troublefreepool.com

Heat Pump Basics - Further Reading

www.troublefreepool.com

 

[Newdude]

I suppose when we have a heated pool though, we'll ultimately get spoiled and want it longer.

Therin lies the problem once you have a heater and don't want to turn it on, or worse, leave it running for two weeks hoping you get one last hurrah that never comes.

With a gas heater, you'll kick yourself for burning 400k btus all summer.

In a perfect world, everyone would get one of each.

I found an interesting price comparison on energy.gov that shows HP vs NG heater cost by city and desired temperature.

Make sure to divide your total PSEG bill by KWH used. The taxes, fees and fuel delivery surcharge often double the bill and aren't included in the calculation.

That said, I really can't imagine going in when it's <70 outside

That's why I ultimately stopped using my HP late. We found that when everybody had hoodies on, nobody wanted to swim. Err. Nobody wanted to get out of the warm pool being wet into cool breezy Sept/Oct air. Lol. Most times when given the chance we opted to take a non sweatty bike ride instead because that was new and exciting in the fall.

I've thought about buying even just a rectangle cover to fit 2/3 of the pool, but it would still be a hassle and honestly ruin the look to some extent.

It ruined the fun with little kids. All we ever wanted to do was race out there and cannonball. We raced out there, then the kids had to sit for 5 to 10 mins while I wrestled the 800 sq ft cover on the real. We all grumbled to an age appropriate level. Afterwards I was all alone with my adult words while wrestling it back on. Stopping the HP was 50% to also skip the cover.

With hopes for PV solar down the line, it certainly skews the thoughts because everyone i know with panels is always looking to waste KWH credits that get bought back for pennies on the dollar.

 

[JamesW]

Heat Pump Heater Sizing

Water Heating Calculator for Time, Energy, and Power

The calculators on this page compute how long it takes to heat water, how much energy is consumed, and how much heating power is required.

gettopics.com

Residential Gas Heater Sizing

 

[1poolman1]

I love the idea of two heat pumps – I’ve been thinking about it for awhile, partly because I repaired one and now have a spare just sitting there unconnected The cost to run two should be nearly identical to the cost to run one – just faster with two, making it possible to recover the needed water temp at a reasonable time of the day after the nightly loss. Of course, in NY that will be a short season anyway, running only during seasons with 75degreesF highs for the daytime, as you say. But a longer season than with one heater. Also with two you get redundancy when one is broken.

I would plumb them in series, not parallel, thus avoiding the need to mess with flow diversion, inadequate flow, or a second pump. My former condo association runs a pair of heat pumps in series here in South FL, I imagine doing so is fairly common to speed up daily recovery from overnight losses in uncovered pools. With the two plumbed in series, I believe the pool service had one of them set 3 to 5 degrees warmer than the other, or maybe just a couple degrees different, I forget. They worked out some logical settings so that both ran to do the bulk of the work, then one of them fine tuned the temperature. One goal would be simply to keep them from cycling a lot, even though they have built in protection from true short cycling.

If those natural gas calculations are correct – wow, I had no idea electric pool heat was so much cheaper than natural gas. Many of us in South FL do not have natural gas service at all, so I never looked into it. Folks deploy large propane tanks sometimes, but that too is very pricey. I suspect you are correct that no tax credits could possibly apply to heating a pool, and I cannot think of any way to call electric heat pump pool heat “geothermal”. Still, worth a look as you say.

@1poolman1 offered some good math for your electric costs, but it would not surprise me if you wound up spending well over that $180 or even $360 per month, perhaps well over $400/month on just pool heat. I say that in part because you’ll be tempted to open the pool more when you can recover “quickly” (eg in 6 hours or so daily), also because you’ll be lucky to get 80% of the rated BTU when it’s cold out (see your heaters COP rating and BTU output spec at ambient temps) – especially in the mornings. And if you have a lot of surface area on a 50K gallon pool your overnight losses – uncovered – could be 10 degrees or more. Here I am in one of the warmest average US temp zones and I lose at least 5 degrees per night (uncovered, 16K gals) in March. If I lose more than 5 degrees on a colder or windier night, I turn off the pool heat because the recovery of those 5 degrees takes about 6 hours and therefore about $5-$6 per day at 15 cents per kwh. For me, that extra $150/month on the electric bill is about the max I’m willing to spend. It would, however, be nice to recover faster, at the same cost! Well, not truly the same cost because the pool would be heated for a larger portion of the day, and when it’s heated the loss rate and evaporation increases. Vicious circle In NY I might go with three heaters and a dome cover over the pool!

Of course, and as you and others noted, the service panel sizing and related breaker and/or subpanel sizings are critical. Best to get permitted and done by qualified electrician, inspected, etc. However, this residential load calculator can give you some good direction for main panels and subpanels – assuming you learn to use it carefully and properly. Electrical Load Calculations for Residential Service Panel - Online Load Calculator

Have fun! ... Joe

You never plumb multiple heater in series. Running heated water through the second will "fool" it into not turning on, especially as the water gets warmer.
I have installed 3 multiple-heater jobs, two 3-heater and one 4-heater all engineered by the heater manufacturer, and they were all parallel installations. Careful measurements of the plumbing was all that was needed to assure fairly balanced flow into and out of each. Valves were used to isolate each in case of needed repairs.
True, they weren't heat pumps, but the principles are the same.

 

[ajw22]

they were all parallel installations. Careful measurements of the plumbing was all that was needed to assure fairly balanced flow into and out of each.

With parallel heaters, the flow requirements are additive. If each heater needs 40 GPM, then your pump needs to run at 80 GPM. You will be running your pump at fairly high speed when the heaters are on, so consider that in your electrical cost.

@NYR56 your signature contains no information about what pump you have or any automation. Good automation can help reduce electrical consumption when the full blast of both heaters is not needed but is another expense.

 

[JamesW]

You can use series by using the automation to control the heating.

If you use a fireman's switch, you might have to add a second relay so that the voltages from the heaters to not interfere.

Power the second relay from the 24 VAC from the first heater.

Two 400,000 btu/hr gas heaters in series would probably be too much unless the flow was about 80 gpm.

Two 140,000 btu/hr heaters in series should be ok at 40 gpm.

At 40 gpm and 140,000 btu/hr, the temp rise is about 7 degrees.

So, 80 degrees into the first heater is 87 going into the second heater and 94 out of the second heater., but the temperature is turned up higher at the heat pump or ignored in remote mode and controlled by the automation.

A parallel setup will require twice the flow, which requires about 8 times the power.

 

[JamesW]

For the second heater relay, pick up the 24 VAC past the first relay and the other leg to ground.

You just need a SPST - NO relay with a 24 VAC coil.

 

[1poolman1]

With parallel heaters, the flow requirements are additive. If each heater needs 40 GPM, then your pump needs to run at 80 GPM. You will be running your pump at fairly high speed when the heaters are on, so consider that in your electrical cost.

@NYR56 your signature contains no information about what pump you have or any automation. Good automation can help reduce electrical consumption when the full blast of both heaters is not needed but is another expense.

If you want to use multiple heaters, that may be what is needed to get them to operate. According to both Laars (now Jandy) and RayPak engineers, parallel is the way to plumb multiple heaters. Your pool, your money, your choice. I'm not and engineer, so I went to the experts.
There are trade-offs in everything we do with a swimming pool.
Want to use a suction cleaner or Polaris 360, the rpms need to be higher while they are in use. Want to use a booster-pump type cleaner, the plumbing may need to be changed or the rpms increased to feed the booster so it will work. Even your heater or SWG may require more rpms than you desire for the largest energy savings.
If that is the case, with a VSP you can change the flow as required for the operation.
On those multiple-heater installations, I was dealing with 5hp and 7.5hp single-speed pumps with 4" plumbing. Had to throttle the flow down with valves so as to not damage the heaters. They were interesting jobs, but a lot of work.