Pool Proposal -- Advice appreciated! -- Westport, MA

[wptpool]

I'm not going to make specific recommendation here. But some info can go a long way.

In most cases BTU is BTU. Everything depends on how fast do you want to heat your pool and at what temp you want to keep it.

Heat pumps are amazing, but is the the exception to BTU being BTU...
This is the spec page for Pentair heat pumps you are going to notice that there are 3 columns for BTU. On each header for a BTU column you will have something like 80 80 80 ... the first 80 is air temp, the second 80 is relative humidity and the third 80 is water temp... same applies to the other two columns. The higher the air temp and relative humidity the better a heat pump performs while the lower the air temp and relative humidity the worst it performs. In early-mid May you should not expect more than 86k BTU from a 140k BTU heat pump. Many heat pumps models allow usage of multiple units in parallel to increase the total BTU of the system, but each one will need a branch circuit that will quickly add up. Also heat pump perform really poorly when air temp is below 50F and only models with anti-freeze can operate below 42F.

This year I was able to get my pool to 89F in later May with an undersized heat pump and solar cover. It took about 4 days for water temp to go from 49F to 89F running 24/7 with air temps between 55F-75F and RH close to 80%. But after that it runs about 3 hours per day to maintain my water temp around 89F.

Also a heat pump as a backup of a solar heating may be less than ideal as a cloudy chilling day will affect both.

Super helpful -- thank you!

 

[jamjam]

I’m in NY and have a heat pump. We don’t have gas and I didn’t want the added expense of propane. My neighbor who has gas switched to a heat pump. Said it was cheaper to operate. But I can’t vouch for that. I do know a gas heater will take you up to temp much quicker.

 

[wptpool]

Thank you @jamjam. Do you use your heat pump much during the summer?
Do you use in the spring/fall? If so, how effective do you find it in the spring/fall for extending your swim season?

 

[Noreaster]

Hello from Sudbury!
When you say you have solar, you mean solar panels on your house for power right? Heat pumps suck in new england EXCEPT if you can power them with solar power. Then its free heat. (unless of course the solar system is not owned by you and is a lease that you then need to buy the power from the actual owner). For the most part, its more economical to run a gas heater. Not sure about LP vs heat pump though.

As far as BTU, the more the better. I can let others comment, but i don't see any reason to under-size.

Another vote for dumping the chlorine feeder and the UV system. Go SWG.

If you don't mind me asking, who is your builder?

 

[jamjam]

I opened my pool in April this year and I ran it for 24x7 to get the water temp up to 80 for the kids. But this spring was so cold I didn’t sustain it because we didn’t have any good stretch of 70s 80s until a few week ago. I basically keep it on n all the time set to 83 and then I program my pump to hit high speed a few hours a day to let the heat pump kick on if it needs to.

 

[Noreaster]

PS: I early summer when i looked at my chilly pool, but its 90 degres out, and i look over at the central AC running. I always wondered why an AC was not combined with a pool heater for max efficiency.

 

[AK-]

PS: I early summer when i looked at my chilly pool, but its 90 degres out, and i look over at the central AC running. I always wondered why an AC was not combined with a pool heater for max efficiency.

There is an episode of this old house that they show a contraption to do just that, heat you pool with your AC.

 

[wptpool]

Hello from Sudbury!
When you say you have solar, you mean solar panels on your house for power right? Heat pumps suck in new england EXCEPT if you can power them with solar power. Then its free heat. (unless of course the solar system is not owned by you and is a lease that you then need to buy the power from the actual owner). For the most part, its more economical to run a gas heater. Not sure about LP vs heat pump though.

As far as BTU, the more the better. I can let others comment, but i don't see any reason to under-size.

Another vote for dumping the chlorine feeder and the UV system. Go SWG.

If you don't mind me asking, who is your builder?

Hello! Yes, solar panels. My concern is how much sun we'll have in the spring/fall as extending our swim season is our main goal. We don't have the natural gas option, just LP.
Builder is Environmental Pools. Construction is scheduled to begin mid-to-late fall.

 

[Noreaster]

Hello! Yes, solar panels. My concern is how much sun we'll have in the spring/fall as extending our swim season is our main goal. We don't have the natural gas option, just LP.
Builder is Environmental Pools. Construction is scheduled to begin mid-to-late fall.

Oh nice! Environmental pool was highly recommended by the guy we had winterize our pool every year. They are supposedly very high end.
Unfortunately they changed the way they do business and were a little to hard to work with this year. The industry is nuts. They wanted someone else to design and they would bid on the project. I was looking for a company that could take this from hello to completion.

You would have to compare how many watts your system generates vs the wattage of the heater.

 

[AK-]

There is one other thing you need to be realistic: Are you really going to swim if air temps are below 60s? You need to take how windy your area is to answer that question.

 

[jamjam]

There is one other thing you need to be realistic: Are you really going to swim if air temps are below 60s? You need to take how windy your area is to answer that question.

that is why i wasn't running the heat pump earlier - i think it only makes sense if you have a target day for an event or you want to ensure sustained swimming over weeks.

 

[bmoreswim]

I would use a heater if I had one from Late May on to keep it at 85 in MD. My pool just reached 85 today. But only because of the autocover. Last few nights have been 50 and dry air. I’ll swim from high 70’s but 85 is my ideal low.

The AC combined setup is tough because if the AC is running you often don’t need pool heat. And when you do need heat, it’s often not running. It is sometimes beneficial but at a cost. Like everything.

For insurance, make sure to mention diving board if applicable. Can be an issue. Was for us. Also highly recommend an umbrella policy if you don’t have one now that you’ve added a big liability in your backyard.

 

[B.lu]

Yes, hi neighbor! Thank you for the info. While from our conversations with the town, I'm confident they won't require us to have a fence in addition to our autocover, the insurance question is an interesting one. This has me looking now at mesh removable fences like this: High Quality Equipment And Tool With Unbeatable Price | VEVOR Official
And thank you for the tips on the heaters. Is it your sense that folks use their gas heaters much in the summer in RI/MA?
I'm naive about them and was guessing they were only (or at least primarily) for extending the season into spring and fall

For the most part, those I know with gas heaters only use at the beginning and end of the season, like you said. But, when I first looked into a heat pump I thought I might like a warmer pool temp than most (I'm a baby about cold water) and liked the idea of using it throughout the summer. I want to be in the pool a lot but also want to be very comfortable temp-wise That seemed possible since the cost to run the pump would be quite a bit less than what I'll be paying for propane. I have solar panels on the house too but not enough to cover all of our needs.

When I was considering the two, the electrician (who works on 35-50 new pools a year)said he only had something like 7 of the pools choose a heat pump. He works in NH, MA, and RI.

 

[Noreaster]

I dont know if its a fair comparison. But i had a condo in VT with resistive electric heat. Resistive electric is 100% efficient. condo was 1000sf single floor, with a heated unit above us. Months of dec jan feb march would be from $300 to $500 ea in electric fees.
We sold that place and got a townhouse across the road. 1800sf, 3 floors. Hydronic baseboard, Propane boiler. $500 in propane a year to heat the place warmer than the former. Propane was way cheaper than electric.
I know a heat pump is over 100% efficient - but i know what it costs to run central AC. In fact i found out the hard way the new house has heat pumps - i quickly set the house to run from natural gas only when i got the NOV electric bill.

From my limited experience - a heat pump can be more efficient. But its rarely more economical. Having solar power can change the equation quick.

 

[AK-]

A heat pump is 4 to 7 times more efficient than a resistive heater (that is the COP value on the specs). A heat pump is more economical because it is more efficient. The issue is if it is going to timely deliver what you need to heat your pool at a reasonable upfront cost (a commercial 500k BTU heat pump is upwards of $45k).