does attic solar heating work?

Nov 7, 2012
26
We just installed an inground pool and I came across some information online that you can take the heat from your attic and use it to heat your pool. It sounds like there might be two brands of the device? One says green machine, one says solar attic, not sure. Does anyone know if this type of system works?
 
Welcome to TFP.

Attic heaters likely work, but not as well as traditional solar panels. Also I would be worried about leaks in the attic with 30+gpm flowing through pipes.
 
It will work to cool your attic towards pool temp. Raising the pool temp, not so much--unless it is a very large attic and a very small pool. The thermal density of air relative to that of water is just too low to make much difference to a decent sized pool.
 
Durk said:
It will work to cool your attic towards pool temp. Raising the pool temp, not so much--unless it is a very large attic and a very small pool. The thermal density of air relative to that of water is just too low to make much difference to a decent sized pool.

I haven't done the math - but there are two big advantages I see of this system:

1) It's hidden - no ugly solar sitting on the roof.
2) It's less directional - it doesn't require a specific orientation.

Downsides:
1 ft3 air raises 1 degree F per 0.02 BTU
1 ft3 water raises 1 degree F per 1 BTU
lack of direct radiant capture limits usefulness in less hot months.

At 90 degrees a 150 degree attic can generate 60 degree delta and then the volume has to be compared. For simplicity let's say the pool and water volumes are similar. The impact of lowering the attic to 95 degrees would be to raise the pool by 1.2 degrees F - this assumes lossless transmission of heat which is unlikely. It's unclear how quickly this energy would be replenished - the rise time of the temp in the attic would help us understand that.

It appears to me this would work best for Spa's and very small pools due to the relative size advantage this would give. When the attic volume is larger than the pool/spa this improves the poential for heating the water.
 
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