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re: recommendations for a humidifier?
16 oct 2001
oggie wrote:
>i live in a place that's around 800 sq. ft. what do you recommend
>in way of a humidifier?
i wrote:
>caulk. people perspire 1 lb h20/day and respire another. cooking, cleaning,
>showers and so on evaporate another 2 pounds, so an airtight space would
>build humidity until condensation begins on the windows. how long does this
>take on a 30 f day in a 70 f room with an r4 window, starting at 50% rh?
the window lets (70-30)/r4 = 10 btu/h-ft^2 pass through its r0.68 inside air
film resistance, so the inside glazing is about 70-10(0.68) = 63.2 f, so
condensation occurs when the vapor pressure pa = exp(17.863-9621/(460+63.2))
= 0.591 "hg, vs 0.748 "hg at 70 f and 50%, ie at 79% rh, when the humidity
ratio has risen by 0.62198/(29.921/(1/0.591-1/0.748)) = 0.00738 pounds of
water per pound of dry air. the room contains about 6400 ft^3 of air that
weighs about 6400x0.075 = 480 lb. one person can add 0.00738x480 = 3.5 lb
of water in 3.5/4x24 = 21 hours.
nick
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