Pool covers (solar)

[bssage]

and my last one was a PITA. I am thinking about slicing my next one in four pieces. Make it a one person job putting it in and taking it out. It may not be "As" efficient as one piece. But I figure I would be more likely to use it more often if it was less of a job. I'm reading your research link now. Thanks

[FormerBromineUser]

I think WaterMom does that with her solar cover. Look in her posts too.

[chem geek]

Technically, the greatest heat gain comes from a clear insulating cover because most of the sunlight is then absorbed by the water but the heat is largely retained due to preventing evaporation by the cover and with an insulating cover by preventing conduction/convection (though not radiation) of heat. As I note in the thread Water Absorption and Heating from Sunlight, around 60% of sunlight is absorbed in a white plaster pool (a dark bottom pool absorbs even more).

An opaque cover will prevent sunlight from entering the pool to heat it directly. The color of the cover then becomes important where a white or reflective cover will heat the water the least while a dark black cover (especially one that absorbs infrared as well as visible light) will heat the most, but the heat transfer to the pool water will be limited due to convection and radiation and the uneven heating of the pool water. The best result with a black cover occurs if the water is circulated under the cover to keep it cool (same principle as with solar water heating panels) and if the black is on the underside of an otherwise clear plastic cover.

I have a mostly opaque electric safety cover and when it was tan in color it did not have any significant heating but now that it is darker blue it heats the pool a little bit. No where near what a clear insulating solar cover would do, but the difference between a lighter and darker cover is still noticeable.

Most heat loss from pools comes from evaporation. The next largest loss comes from radiation (for outdoor pools, not indoor) and the lowest loss comes from convection though if there is wind then convection losses can be greater than radiation losses, but losses from evaporation are still the largest by far. So any water vapor barrier cover will cut down most of the heat loss by eliminating evaporation. An insulating cover then additionally reduces losses from convection. A completely opaque and well insulated cover will retain the most heat, but it will also block sunlight from heating the pool directly. So indoors that would be best. Outdoors, a clear insulating cover is better as it will let sunlight add heat to the pool.

See this document for the technical methodology used by the EPA for Energy Star® performance ratings for swimming pools.

[JimK]

So my instincts were right.

[bssage]

Nice,,,,Thanks,,

So I am dumbing this down for myself and checking my understanding with your.

Since my pool is an outdoor, AG, In Iowa. I want to both gather as much heat as I can, and keep it in the pool best that I can.

The best "Bang For My Buck" is a clear insulating cover, Not a Solar Cover? Preferably one with a Mill thickness that would allow me to run my pump with the cover on during the hottest parts of the day??

Does anyone have an Insulating cover they recommend??

And hey, If my understanding is incorrect. Feel free to correct me.

[FormerBromineUser]

Interesting info, ChemGeek! One part seems strange, though. Year after year with my auto-cover, I actually have to open it during the day in the hottest times of summer to cool the pool down. My water temps (when compared to cover on during the day vs off), tell me that cover-off will cool the water more than cover on. (Hope that makes sense). Maybe that's been a fluke.....

[JimK]

Interesting info, ChemGeek! One part seems strange, though. Year after year with my auto-cover, I actually have to open it during the day in the hottest times of summer to cool the pool down. My water temps (when compared to cover on during the day vs off), tell me that cover-off will cool the water more than cover on. (Hope that makes sense). Maybe that's been a fluke.....

Cover off = more evaporation = cooler water.