Keeping pump running over winter with heat pump


Gold Supporter
Aug 31, 2015
Harrison, NY
I've been benefitting from this forum for years. Because we live in the NE, for all that time, I've been draining down the water level to below the return jets, blowing out the lines, etc. In other words, winterizing by the book.

Today, I covered our pool (mesh cover) to avoid the coming leaves. The bottom was clean and the water clear. While I was working I began to wonder: "do I need to drain the pool if I keep the heat pump set for 42 degrees F and leave the pump to circulate water?" I calculated that I would spend $250 on electricity to keep the pump running over the winter. That is far less than I spend on replenishing salt, calcium, etc. at the start of every season (I have a SWG). I have no idea whether the heat pump would need to be run or not (e.g., would the average water temp of a 35K gallon pool fall below 42F?). BTW, we have a generator that could supply power if we do have a power failure.

Is this experiment nuts?

I've seen this question addressed for lower latitude owners, but not for someone as far north as us (apologies if I missed something).

The average temperature in Westchester NY is below freezing only in January, but we can get cold spells in the teens. I found I can set our heat pump to 42 F (it's lowest setting) so it should be able to keep the water warm enough to not freeze up, right?

The positives that I could imagine would be:
1. Cleaner water in the Spring.
2. Less need to add chemicals to rebalance in the Spring.
3. Basically, an easier opening.

The problems I could foresee:
1. Precipitation would require me to pump out water periodically and negate savings of chemicals
2. Heat pump might need to run more than I anticipate.
3. Unnecessary wear and tear on equipment.

So I return to my question: Is this idea nuts? misguided? uninformed?

Thanks for any feedback.


Jun 15, 2018
Highland, MI
Heat pumps work by extracting "heat" from the surrounding air. As the ambient air temperature drops that becomes harder and harder to do. Even though you may be able to set it as low as 42, have you checked the manual to see if there are any caveats about doing so? It would not surprise me if the unit ends up running much more than you expect. Lastly, if you get temps down into the teens there is absolutely no way your heat pump will be putting out warm water, at exactly the time when you need it most.


Silver Supporter
In The Industry
Aug 15, 2017
Spring Valley, NY
The hp will struggle at best but if it crapps out during a cold spell what are you to do. By the time you realize the hp went south it may have taken the plumbing with it. Not a great experiment. At $250 I'd rather by the chemicals and know I have a pool.


Jul 2, 2020
Pittsburgh, PA
Pool Size
Liquid Chlorine
I think your "experiment" would be far more doable if you had the things below.

1) A Gas heater in the 330K BTU range.
2) Some way to insulate the top of your pool better than just a cover (maybe they sell a insulated cover). Perhaps a bunch of flat pool foam float pad or some other type of foam under your regular cover! ;)
3) Filter and pump indoors (or in an insulated shed with the gas heater in there also), and all above ground external plumbing insulated.
4) Shut off water flow the HP, as it would be very inefficient, and pretty much ineffective at air temps below 50F, unless you have one of those IceBreaker types, which still likely isn't all that efficient at those temps.

IMHO, this type of setup would be far more doable if you had one of those Pool Enclosures over your pool. Then you get the greenhouse effect during the day, which helps moderate the heat loss from your pool. Of course, you will still get heat loss through the walls of your pool into the ground, especially if you have concrete or metal wall pool. So, the next time you replace your vinyl liner, put 2 inch XPS board behind the liner, to minimize heat loss. Of course that board has to be able to handle the PSI of water weight.

I am already thinking about how to keep my pool in Pittsburgh, PA open longer than May through Oct, in a more comfortable setting. And the Pool Enclosure is at the top of my list, with the items I've mentioned above.

Of course, it would just easier to get a hot tub! :)


Silver Supporter
Bronze Supporter
TFP Guide
Oct 20, 2017
Southern WI
Pool Size
Liquid Chlorine
Of course, it would just easier to get a hot tub! :)
Best time to use a hot tub is in the winter. Ours is open year round here in Wisconsin.
  • Like
Reactions: coolviper777
Thread Status
Hello , This is an inactive thread. Any new postings here are unlikely to be seen or responded to by other members. You will get much more visibility by Starting A New Thread