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re: solar barn update -- one last question
14 sep 2004
gary wrote:
>> >>>>you might preheat dhw in 5 btu/h-f-ft fin-tube pipe...
>recently in my south facing grey tiled roof the temperature up there was
>55c. i considered using finned tube at the apex, but when winter comes it
>freezes up there.
maybe the pipe needs insulation above
/
b b is "r7.2" 1" poly iso board
b b 6" p is the pipe
b p b f is the fin
b f f b /
b f b
and a battery-backup freeze-protection circulation pump (which might also be
a collection pump) or another piece of thermosyphoning fin-tube in the house.
a 32' pipe in a 10 f attic would need about (32-10)32/7.2 = 98 btu/h
to avoid freezing, eg 98/(60-32) = 3.5 pounds per hour or 0.007 gpm
of 60 f water.
>then there is the problem of condensation dripping off the pipe.
and a gutter below, or a dew point circ pump controller.
nick
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