Can you do the math? Koozie for my above-ground pool.

[DeAnna64]

Hello again everyone. Been using our new solar heater for our 15-foot above-ground pool and we love it! Actually took a swim a couple times last week . . . in November! The pool was a comfortable 82 degrees. However, now that it's getting a bit cooler here in central Florida, the solar heater is struggling to get to 80. The heater says the water on the roof is 117 degrees. But what is happening is the pool gets to 82 and then goes back down to 75. Up and down up and down. It never gets a chance to keep that heat inside.

So, I had an interesting idea. We have a solar blanket for the pool. How about something to go around the outside of the pool to keep the heat in? I really think that is where most of the heat loss is at night. When we get in, you can feel the coolness on the inside wall.

So that is when the argument began between me and my husband. He wants to see the numbers because he doesn't think it will do much to retain heat. I've seen a wrapping called "double bubble." It's for above-ground pools. It's bubbles on one side and reflective on the other. I'm sure there's other kinds of waterproof barriers that could be used. He's also worried that if it's not right up against the walls, it won't work. We have braces about every four or five feet. The barrier would have to conform to those somehow.

I guess what I'm interested in is if anyone has done this and been successful. I just want a couple of degrees since right now the pool temp is stuck between 78 and 79 in the afternoon. What do you guys think?

 

[woodyp]

I think wind is more your enemy on the sidewalls.

 

[Newton4mark]

You may be better off using spray foam on the outside of the pool

I would think it would work just not sure how good it would look

Unless you built a big deck around it so it was covered

That’s pretty much how they build standalone fiberglass spas
And it works well

Yours would just be a much larger version

 

[Poolzzz]

I've done it with great success. My pool is currently insulated top, bottom and sides. Air remperature is around freezing, a little below zero at night and maybe 5° C during the day. Pool temperature is set at 36° C (high 90's F) and kept there using a 1kw electric heater which is overkill for my pool even with snow on the ground.

Sounds like you have a solar cover so that addresses evaporative heat loss which is the easiest and cheapest to fix. After that you still have radiative and conductive/convective heat losses which occur through the top, sides and bottom. As you've discovered they can be significant.

Your top and sides are roughly the same surface area and will lose similar amounts of heat (usually slightly more from the top than sides). The bottom will lose less because the ground is probably warmer than your average air temp these days plus the ground has some amount of insulating properties (although not nearly as much as the textbooks say).

So you are absolutely on the right track.

Your bubble reflective wrap idea only addresses the radiative portion of the heat loss on the sides. And this is only if done right and even then not 100% effective. Done right means you must have a 4-6 inch air gap (ie dead air space) on the inside with nothing touching the wrap on the inside. And the top must be sealed to limit convection through the gap at the top. I did this and it made a difference. It might be enough for you since your desires are modest. You could try it and see if it does enough since it shouldn't cost much and won't be wasted if you need to do more. My gut says it will be borderline though so you should be prepared to add some insulation if needed.

I needed significantly better results so did much more. I wrapped 1" rigid pink Styrofoam insulation around the sides as well (using two layers of 1/2"). With the reflective bubble wrap plus insulation it made a big difference and probably plenty for you.

I also put 2" rigid insulation on top which made a huge difference when combined with the side insulation. With the top, sides and another 2" rigid insulation on the bottom I can practically heat my pool to hot tub temperatures with the proverbial candle! Lol

I've bent 1" pink rigid insulation around an 18 foot pool and it might also bend around a 15 foot pool. It won't bend around a 12 foot pool but 1/2" will. The rigid pink seems to stand up to the weather and can be painted for further protection. I never looked into spray on insulation since the rigid pink works fine for me.

 

[Swampwoman]

70 percent of heatloss is evaporation, and the balance (20 and 10%) are radiant and conductive loss, in general.

So, the insul foam board is a great idea to reduce the conductive loss as described above, and will also reduce your radiant loss just like a hottub, but the question is if you're relying on solar as your heat source, can you build enough heat for the temp you want.

You might want to check out this calculator...it shows the difference between insulated pool walls and not, but I think as applied to in ground pools: either way, the calcs may give you insight: SWIMMING POOL ENERGY TEMPERATURE CALCULATOR | Neil Anderson

Ps - I read up on all this stuff last year because I bought an air dome for my Michigan inground, gas-heated pool. That site was both helpful and pretty accurate re energy costs.

I've been able to operate all winter long last year, and hopefully this year, in sub-freezing temps. My pool is 95 degrees this am for my physio, with air temp of 60 and a balmy 42 outside

So a winter "dome" is also a possible option for you if you cared to make the investment. The dome to some degree reduces the rate of heatloss. But insulation would still be critical.

Here's a pic from inside the dome the other morning before things steamed up too much (which, btw, happens

 

[Poolzzz]

70 percent of heatloss is evaporation, and the balance (20 and 10%) are radiant and conductive loss, in general.

There are a lot of variables that significantly affect these ratios even for the same pool.

As a general statement I'd say significant heat loss in above ground pools occurs from evaporation. Since it is the easiest to fix it should be addressed first. However the non-evaporative heat losses are often large enough to require attention also (either by insulation or additional sources of heat).

 

[DeAnna64]

I covet your dome! lol Thanks so much for the info.

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Thank you so much for reply. These are great ideas. I appreciate your help.