|
|
re: heat sources (was: re: building a house in the country)
14 jul 2001
dave hinz wrote:
>any thoughts on using a strictly gravity feed for the wood furnace?
>does anyone have formulae for calculating how much flow i can expect,
>and how much i need?
how much you need depends on the house heat loss. say it's 50k btu/h.
how much you get depends on the temperature difference and vertical
distance and duct size. if cfm = 16.6asqrt(hdt), the heatflow is
approximately 16.6asqrt(h)dt^1.5, ie 188dt^1.5 btu/h with an 18"x32"
= 4 ft^2 duct and an 8' height difference, so moving 50k btu/h makes
dt = (50k/188)^0.667 = 41 f, ie the air around the stove may have
to be 111 f to make the upstairs 70 f.
otoh, grainger's $37 20" 4550 cfm 165 w 4tm67 box fan with thermostat
can move 50k btu/h with a 50k/4550 = 11 f temp difference. their $115
48" 21k cfm 86 w 4c853 ceiling fan can move it with a 2.4 f difference.
you might consider casting a flat coil of 1/2" soft copper tubing into
a thin form-fitting reinforced concrete stovetop and moving the heat
with water vs air...
nick
|
|
