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re: boiler for hot tub
4 aug 2000
elaine gallant wrote:
>my father-in-law bought a cedar hot tub. he wants to heat it with wood.
>what is the easiest, least expensive sort of wood heated boiler?
anna edey's 1998 solviva book describes
...a 7' diameter, 2' deep galvanized steel farm stock tank from sears,
which cost about $230... i created a fire chamber... a trench 7' long,
2' wide and 18" deep. for the purpose of creating a lining for the
fire chamber, i cut a 50-gallon oil drum in half lengthwise... the
bottom of the drum was left on one of the halves, and a 6" hole was
cut into it for the chimney pipe. i laid down the 2 oil drum sections
to form a 6' liner, with the stovepipe cutout at the far end. i packed
the ground firmly in an 8' circle, and pressed four 8' angle irons into
the ground, laid across the fire chamber. then i laid a 7'x7' piece of
heavy sheet metal on top, to serve as a hot plate. a 6" stovepipe was
installed, leading from the end of the fire chamber... and the tub was
set on top of the hot plate, then filled with water. a roaring fire...
is capable of heating the 600 gallons of water in the tub from 55 to
over 100 degrees in less than 2 hours...
the cedar bottom has more thermal resistance than steel, so the water
wouldn't heat up as fast, and the tub might char or catch fire. maybe
this needs a sand or masonry base with some pipes in it to circulate
water through the tub...
nick
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