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re: solar closet water heat storage medium
17 sep 2003
thomas wrote:
>>how big is the building? how much insulation?
>
>each level is 1100 sq ft. lower wall is standard cinder block and r11 poly
>board on the inside, upper level walls are walls are r19 attic r30
that's about 1100ft^2/r30 = 37 btu/h-f for the attic plus 176ft^2/r2 = 88 for
windows(?) plus 1947/19 = 102 for walls(?) plus, say 1achx17600ft^3/60 = 293
for about 293 cfm of air leakage (which might be reduced a lot, with caulking),
so the total thermal conductance might be about 432 btu/h-f.
> my thought is to make a sunspace on the south side on the ground
>approximately 15 feet wide by eight feet high x eight feet high.
>typo this should 15w x 8h x 1 or 2ft deep
seems easy to make it bigger, with more solar gain and useful floorspace.
>>sounds good. you might make it bigger. you might collect 0.9x980x8x15
>>= 106k btu of sun from the south and 0.9x610x8x15 = 66k of overhead sun
>>and lose about 6h(100-30)200ft^2/r1 = 84k btu on an average december day,
>>for a net gain of 88k btu/day, a bit less than a gallon of oil. how does
>>that compare with your fuel bill?
>
>i do not know how to compare fuel bills to 88k btu's.
>i have propane and ng is not an option.
as i recall, a gallon of propane contains about 92k btu.
>average bill winter dec02 jan and feb 03 was 350.00
...$350/mo is about $6/day, equivalent to about 6 gallons of oil per day.
you might double the sunspace size with no thermal storage without wasting
much solar heat in december. at 432 btu/h-f, your house would need about
24h(65-32)432 = 342k btu/day to stay 65 f on an average december day in nyc.
>this suggest to me an exterior trombe wall with metal backer or other
>material to heat the air faster.
trombe walls are badbadbad in se ny. thermal mass cripples solar performance.
>perhaps is is more prudent to heat the air rather than attempt to store
>the heat (thus making it over complicated).
good idea, unless you are shooting for 100% solar house heating.
>is the air flow in my previous post reasonable (pull from lower level, dump
>in upper level)??
sure.
nick
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