Deciding between natural gas heater and electric heat pump

[lhlsea]

Where did you get this? What are the formulas behind those cells?

Having had pools forever those numbers just don't add up. I noticed you are using therms, that is a billing calculation number.

You need to use actual btu (gas) and kwh (electric) converted to btus to determine the energy need to change the temp of the water.

Home heat pumps use heating strips (resistive heat) as backup when the units cannot produce enough energy to meet the demand. If these pool units have none then the system is useless below 50F. Gas will always produce.

Thanks. I made the spreadsheet myself but the values themselves are copied out of an online calculator at noanderson.com where you enter a bunch of assumptions and it spits out the monthly costs. In my case I chose the assumptions listed at the top of the image.

Based on your experience are the monthly costs coming out too high?

 

[cjpwalker]

1 therm = 100,000 btu

 

[lhlsea]

Thanks again everyone for your advice here. I got some info from the prior owners. They said

- they heated the pool from around Memorial Day to Labor Day (depending on weather)
- kept it at 83
- no cover
- gas bill was around 300/month during that period

I am hoping I can do better than 300/month (e.g. If I get a cover) and perhaps the new heater will be more efficient. Though it would be nice to have a bit longer swim season than that.

All that said, i like the idea of the electric heat pump but it seems like it will take a long time to pay back the extra $4100 it would cost me upfront. If they were paying like $1000-1500/year in gas and if electric were half that, it would take me 6-8 years to payback, and that assumes I do nothing different (I.e. No cover) and that my assumptions I used in the calculators are all correct (which is a big bet since I haven't done this before).

So all things considered I think I will go with a gas heater, do my best to keep costs down, and hope for the best!

Thanks again for all the help in this thread -- really useful!

 

[CaptainCannonball]

I still don't see where you're going to spend $2000-$3000 a year on gas just to heat the pool. Even $500 a year seems like a way off number.

In many places natural gas is alot cheaper then electric plus you're getting real heat.

A btu is a btu, real or otherwise. Every situation is different and I could see spending that where gas costs $2+ a therm. With an 80% efficiency heater that's 40,000 btu for a dollar, no thanks... unless I do some fracking in my backyard

Now if I had a spa or wanted to go swimming when it's 50 degrees, I would pay the $8-10 an hour admission fee to run a gas heater here.

 

[waterl0gged]

Thanks again everyone for your advice here. I got some info from the prior owners. They said

- they heated the pool from around Memorial Day to Labor Day (depending on weather)
- kept it at 83
- no cover
- gas bill was around 300/month during that period

I am hoping I can do better than 300/month (e.g. If I get a cover) and perhaps the new heater will be more efficient. Though it would be nice to have a bit longer swim season than that.

All that said, i like the idea of the electric heat pump but it seems like it will take a long time to pay back the extra $4100 it would cost me upfront. If they were paying like $1000-1500/year in gas and if electric were half that, it would take me 6-8 years to payback, and that assumes I do nothing different (I.e. No cover) and that my assumptions I used in the calculators are all correct (which is a big bet since I haven't done this before).

So all things considered I think I will go with a gas heater, do my best to keep costs down, and hope for the best!

Thanks again for all the help in this thread -- really useful!

I think you made a wise choice . I love our heat pump , but in your situation, I would have definitely just had a gas heater reinstalled since all the hook-ups were already there .
Our heat pump does an awesome job of keeping our pool at our desired 88 deg. temp for very little $$$ per month , but sometimes takes a few days to get to the target . In a perfect world , I would have a gas heater for the quick initial temp boost , and the heat pump for maintaining the temp .