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Posted by on June 9, 2007, 3:08 pm
On 9 Jun 2007 14:17:21 -0400, nicksanspam@ece.villanova.edu wrote:
>>Why would anyone need to heat a pool if the AC was on?
>
>Another Small Matter of Physics (SMOP.) Consider Jacksonville in June,
>with a 79.3 average temp and a 89.3 F daily max and a humidity ratio
>wo = 0.0157 and vapor pressure Pa = 29.921/(0.62198/wo+1) = 0.737 "Hg,
>vs Pw = e^(17.863-9621/(460+75)) = 0.887 for 75 F pool water at 100% RH.
>
>ASHRAE says a 30'x40' uncovered pool would lose 24hx30x40x100(Pw-Pa)
>= 433K Btu/day, like a poorly-insulated McMansion with a 1000 kWh/mo
>indoor electric bill and a 1400 Btu/h-F thermal conductance to outdoors.
It is a lot easier and cheaperr in the long run to just use solar
collectors. That magic month where the A/C is on and the pool is still
too cool will not pay for connecting up a heat recovery system.
I bet there are still people in Jax who don't have the AC on yet. I am
only using mine intermittantly in Ft Myers/Naples and my solars are
shut off already.
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