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re: thermal mass and ground loop heat pump question
28 jan 2001
abby normal wrote:
>>we might freeze a $500 24' diameter x 4' deep 15k gallon swimming pool
>>solid with 15kx8x144 = 16.7m btu, enough heat for a month or two.
>>it might have a solar pool cover...
>i guess anything is possible but you would have to have a cistern below
>ground to be insulated from the elements...
i'm not sure about that. exposing the top to the sun and the bottom to
warmer earth seems useful. the sides don't have much surface compared
to the top and bottom, but they might have r10 foamboard insulation.
>need a bigger, heavy duty cistern for 10,000 plus degree days...
maybe not, if the sun shines in the winter. international falls, mn has
10487 dd, with a 36.8 f deep ground temp. the average air temp is 7.2 in
december, and 750 btu/ft^2-day of sun falls on a south wall, with 350 on
a horizontal surface. say a 400 btu/h-f house sucks 30d24h(70-7.2)400
= 18.1m btu out of the pool, and it gains 30x450ft^2x0.9x350 = 4.2m from
the sun and loses 30dx24h(32-7.2)450ft^2/r1 = 8m to the air...
well, maybe the pool needs a reflector, eg a white semi-cylinder 12' above
the south wall that adds 5.8m btu in december. then again, maybe the house
keeps itself warm on an average december day, with an average amount of sun,
and the pool only supplies dhw and cloudy day heat...
nick
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