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re: furnace size
18 dec 1999
wrote:
> { sigh }
> there is no way on this planet to answer your question. what
>you need is to have a competent contractor come out and do a heat loss
>calculation on the house. expect to pay for this valuable service.
>then and only then will your question be answered. anyone who says
>otherwise to you is full of shit.
pieca cake:
>>i'm hoping someone can give me a ballpark idea on what size furnace i would
>>need for a 1750 sq. foot house. it's one level on an insulated crawlspace.
>>the wall have r-19, the ceilings have r-38. all the windows are double pane
>>insulated. and it is in the middle of missouri.
about 140ft^2/r2 = 70 btu/h-f of windows, 1600ft^2/r19 = 70 for the walls,
46 for the ceiling and 1achx8x1750 = 254 for air infiltration, if it's
reasonably new and airtight, vs old and draughty, for a total
thermal conductance of 440 btu/h-f.
nrel's record low temp for columbia, mo is -20 f, so you'd need about
(70f-(-20f))440 = 40k btu per hour of peak heat transfer capacity,
something like an automobile radiator, aka "fan-coil unit" in
hvac criminal terms.
no furnace is needed, just a concentrating solar attic to collect about
730 btu/ft^2-day of available direct beam sun from the south in december,
when the average daytime temp is about 35 f. you could store 150 f
rainwater in a few $420 1500 gallon poly tanks in the crawlspace.
some ashrae-standard 5.41 pound 58.53 btu/h bunnies or
6.61 pound 68.02 btu/h cats could help as well.
nick
...in fact, there was once a newspaper report in oregon where the
grower used rabbits in great numbers to provide most of the heat
for the greenhouse.
from greenhouses: advanced technology for horticulture
by joe j. hanan, crc press, 1998, 684 pages, $100,
isbn 0-8493-1698-7.
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