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<DIV>>... If all you want is hot water, you might not need a whole</DIV>
<DIV>greenhouse, just a long east-west water-filled polyethylene duct</DIV>
<DIV>on the ground inside a larger duct that's filled with air during</DIV>
<DIV>the day and soap bubbles at night.</DIV>
<DIV> </DIV>
<DIV>We could start by putting 48' of 2"x4'x8' Styrofoam over a $66</DIV>
<DIV>12'x50' piece of 4-year 6-mil polyethylene film on flat ground,</DIV>
<DIV>then place a $43 24" diameter x 48' long polyethylene film duct</DIV>
<DIV>from <A
href="http://www.greenhousemegastore.com/product/power-tube-tubing/fan-jets-power-tubes">http://www.greenhousemegastore.com/product/power-tube-tubing/fan-jets-power-tubes</A></DIV>
<DIV>on the Styrofoam, then raise the film edges and seal them together</DIV>
<DIV>with 2" horizontal plastic conduit at the top to make a 4'x4'x4'x50'</DIV>
<DIV>equilateral Tablerone bar with supports for the conduit every 8' or
so,</DIV>
<DIV>then fill the duct with about 9400 pounds of water and make an
opening</DIV>
<DIV>for soap bubble foam near the bottom of one triangular endwall and</DIV>
<DIV>another opening for an air return near the top of the opposite
endwall,</DIV>
<DIV>like this, viewed in a fixed font:</DIV>
<DIV> </DIV>
<DIV>
conduit
conduitconduitconduitconduitconduit</DIV>
<DIV> f
f
e
e air --> </DIV>
<DIV> f
film
n
n</DIV>
<DIV>4' f f
4'
d
d</DIV>
<DIV> f
f
w
w</DIV>
<DIV>f duct
f a
ductductductductductductduct a</DIV>
<DIV>f foamboard f foam -->l
foamboardfoamboardfoamboard l </DIV>
<DIV>fffffffffffff
lfffffffffffffffffffffffffffffffffl</DIV>
<DIV>
4'
50'</DIV>
<DIV> </DIV>
<DIV>On an average January day in Phila, the film envelope would be filled</DIV>
<DIV>with air, and it would transmit about 0.9x50'(1000x3.46'+620x4') </DIV>
<DIV>= 267K Btu. Over 6 hours with water temp T, it would lose about</DIV>
<DIV>6h(T-34)50'x4'/R1 Btu/day. With no useful heat output, T = 257 F :-)</DIV>
<DIV> </DIV>
<DIV>At 140 F, it could supply about (140-80)9400 = 564K Btu to a house.</DIV>
<DIV> </DIV>
<DIV>Nick</DIV></DIV></DIV></BODY></HTML>