Heat pumps and are they worth it for me?

[Aaronbr]

First time posting but I have been lurking around lately, finding answers I have about pools. I have searched this site, and many others, but can't find a definitive answer about heat pumps, only finding conflicting information. I hope someone can help and clear things up for me. I read many posts and reviews stating a heat pump for a pool is a very cost effective way to heat the pool yet most pool builders I have had come bid on a pool build won't install a pool heat pump. They tell me it uses a lot of electricity and that they aren't reliable, breaking down every 2 - 4 years. I do have an 8kWp solar system on my house, but the pool builders tell me I'd need about 15 more pannels to run the heat pump. I've clarified that I'm asking for an electric heat pump and not an electric resistive heater but their answer doesn't change. They tell me if I bought one they would install it for me but they won't warranty any part of the heat pump. The one company that does offer a heat pump tells me to try the pool for a season without and then reasses if I think I really need it. So what is the deal with these heat pumps that everything I read about them sounds like they are amazing? Should I pass on adding an electric heat pump along with my gas heater? Are they really not worth it? Here are some specifics of my system and pool I'm looking to get:

I live East County San Diego, in Santee to be exact. Summer temps are hot, it will get in the 100's during the day and 70's at night. Winter temps are mid 60's during the day and as low as 40 at night.

I will have an auto cover on the pool which will be closed unless we are actually using the pool
Overall size is 36 feet long by 22 feet wide. 3.5 foot depth at each end and 5 foot depth in the middle
8kWp solar panel system on my home. Each year I use about 4 MWh of electricity from the city, but give them about 9.75 MWh of electricity
Electric cost is roughly $.36 off peak and $.61 during peak hours (4pm-9pm)
Gas cost is $.36 up to 5 therms, $.31 5-8 therms, $1.44 8-13 therms, then I'm not sure after that.
My pool will be roughly 22,900 gallons to include a sunken spa.

 

[mknauss]

Heat pumps are designed to be most efficient in climates that are warm (day and night) and 80% plus humidity.

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www.pentair.com

You will need a gas heater for the spa. So no real reason to get a heat pump. In your climate, a solar heater will be best for the pool water. Covering the pool will retain a lot of the heat.

 

[Aaronbr]

Thank you! I had a feeling humidity had a part to play in it. It is still difficult to comprehend how a heat pump wouldn't do well when we have so much sun but when all the pool builders are telling me it isn't worth it I should listen. It'll save me close to $8,000 not having a heat pump installed with the gas heat. I was trying to avoid a large gas bill, but if the heat pump doesn't make sense in my area then I will stop considering it.

 

[stevo777]

I was also considering a heat pump; PB included one in neighbor’s new build. They have PV solar (so do we), the intention was to take advantage of that free energy to heat the pool. I ultimately decided not to request one for the following reasons:

1. we live in the desert, hot summers, and dry climate.
2. Use of the HP would be limited to a small number of weeks in spring and fall, as we would not use the pool in winter, and with the cover, don’t need heat in summer.
3. Still need gas heat for spa.

 

[House2021]

I live in los angeles where the weather is very similar and have a 140k btu heat pump and PV solar. It is able to raise my 33000 gallon pool about 1 degree every 1.5 hours and it uses 7 kwh to run. With my 9.18kw pv system im able to keep the temp at 82 between May and Oct without paying a penny for electricity. I do not have a spa or gas heater. I paid $3000 for mine and installed it myself. For $8000 cost your breakeven will be very long. With your 5 mwh excess electricity you will be able to run the heat pump for 700 hours per year for free. That is probably 700 degrees of pool temp increase or about 5 degrees a day increase during the warmer 5 months of the year. I would not recommend using it in the winter

 

[PoolGate]

Even if it did make sense, and provided you are doing this for cost savings, how would an ROI play out with an $8000 additional expenditure?

 

[Aaronbr]

Thank you everyone, you have all helped me make a decision on the heat pump and realize it isn't the best investment for where I live. That 5.5 MWh excess electricity from my PV is really only about 2.5MWh excess due to how they price electricity, buying excess electricity from me during the non peak price at $.36/kwh but selling me electricity at $.61/kwh when I'm not making any electricity. I was refusing to believe that a heat pump wasn't worth it but I have now "seen the light" so to speak. The auto cover will help heat the pool as well as keep the heat in making the use of the gas heater minimal. It was mainly winter I was most concerned about, but using a heat pump during winter isn't advisable anyway.

 

[AK-]

Heat pumps extract exchange heat from one medium to another… when heating it will extract heat from air and transfer it to the water. Water vapor holds way more heat (actually entropy) than dry air what makes heat pumps more efficient on humid climates. Same reason why deserts are cold at night.

Some heat pumps also have the ability to cool your water, so if you live in a place where your water heats too much during summer then you might have another use for your heat pump.

The $8K price tag seems bit salty considering the installation is very simple. Mine is quite small (50K BTU) and paid about $2.2K (installed it myself). I have seem Raypak 140K BTU heat pumps on inyopools for about $3.4K.

 

[Aaronbr]

Yes it is pricey. It's actually $7,500 to install the Pentair 140k BTU with a 50 amp circuit.

 

[coolviper777]

Yes it is pricey. It's actually $7,500 to install the Pentair 140k BTU with a 50 amp circuit

A heat pump like that is around $3.5K to $4K. Running the 50 amp circuit can add a fair amount of cost depending on how far you are going. I had an 80 foot run, and had to trench about 60 feet, and run #6 AWG THHN in liquid tight conduit and put up a subpanel. Given how pricey contractors are these days, I have no doubt quotes would've been in the $10K range if I had someone install my HP and subpanel/wiring. Rant on: I am all for someone making a decent living, but it seems the trend lately is many contractors are gouging their customers, so they can buy that $75K loaded pickup truck. Maybe I am unfair, but it's crazy how many I see driving around in these expensive pick ups. And they don't look like they're used for business. Rant off.