Heat Pump Advice - Pump Speed?

[LookMomNoHands]

Help! I need to heat my pool as much as possible in the next 24 hours... I have variable speed pump. Should I run the pump the slowest required or at max speed?

I can’t wrap my head around which way to go!

 

[mknauss]

Welcome to the forum!
Run the pump at the minimum speed needed to satisfy the pressure switch in the heater.
More importantly is to have a cover on the pool to retain the heat, especially over night.

I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.

 

[LookMomNoHands]

Thank you... that makes sense to allow for better heat transfer I assume...

Follow up question: I have two skimmers and also main drains in deep end. Pool is covered with solar cover. Not much skimming going on. Should I close skimmers amd just pull from bottom drains, to essentially heat the coldest water, and not just recirculate at the surface?
Again max heat is my goal!

 

[ajw22]

You are over thinking heating. BTU's are all the same and heat the water by transfer from the heater to the water. If the flow is sufficient for the heater to run the heat BTU's will be transfered from the heater into the pool water.

The mixing of the water across your pool starts with where your returns are, not where you skim from. The warm water gets into the pool from your returns and then the heat needs to get mixed across the entire water body. You will have some heat differential across the pool water.

 

[kefjens]

Recalling some long ago Thermodynamics classes, the heat transfer would be greater as the velocity increases. The increased flow rate would result in an increased potential theoretically resulting in a higher transfer of energy. I have a feeling that in practical application for heating a pool, it probably is going to be pretty much the same amount of total heat transferred between high and low speed.

Warm water is going to want to rise to the top anyways so you might as well pull from the drain. Assuming the water at the drain is coldest, that will yield the highest potential.

 

[LookMomNoHands]

It seems to me that if my returns are near the surface, and I’m pulling from the skimmers also at the surface, that I’m just creating a surface circulation patter, if you will. I closed the skimmers for now, pulling just from the bottom drains, trying to create more of a whole-pool circulation pattern. We’ll see how it goes.

Background: I’m in CT and hosting a birthday pool party for my 8-year-old daughter and her friends.... temps have not been friendly, so I’m trying my best to get it warm and enjoyable for them!

 

[kefjens]

My 250,000 btu natural gas heater will increase the temperature of my 21,000 gal inground pool by about 1 degree per hour. I just took the cover off a couple of days ago and the water was at 54 degrees. Best case, I'd be at about 78 degrees after 24 hours of heating.

 

[ajw22]

Details of your pool in your signature would be helpful. Not knowing anything about what type of pool, size of pool, type of heater, BTU of heater, etc makes it difficult to give more specific advice.

Getting some solar blankets to get on the water to prevent loss of heat over night will do more then fooling with valves. See if any local pool stores or Walmarts have something you can get this afternoon.

 

[spatel95]

I would turn all the return jets toward the bottom. That should mix the water well.