re: frugal way to dry out damp musty basement.
3 aug 2003
stormin mormon wrote:
>>i'm thinking about our church. one member seems to believe it will fall down
>>unless we run a dehumidifier 24 hours a day all summer, and we pay something
>>like 20 cents/kwh with a demand meter. amana's 40 pint per day unit uses 660
>>watts. they have bigger ones.
>can you pull the dehum apart, and unhook one of the wires to the compressor?
i think she would notice. a few of weeks ago, i put a humidity meter in the
basement, in response to a sign "leave this dehumidifier on all the time,
to avoid curling the acoustic ceiling tiles," thinking we might come to
an agreement on the max rh (70%?) to avoid curling...
but venting with outdoor air when it's drier still seems a better solution.
if it's say, 75 f and 70% rh indoors, pi = 0.7e^(17.863-9621/(460+75))
= 0.621 "hg, so wi = 0.62198/(29.921/pi-1) = 0.0132 pound of water per
pound of dry air (vs phila's 0.0130 outdoor average in august.) we might
run the fan whenever wo < 0.9wi = 0.0119, ie po < 0.560 "hg, ie
ro < e^(9621/(460+to)-18.44)), eg
90 f <39% we might remove an average of 40 pints of water per day
85 f 45% by ventilating with 40/(0.0132-0.0119)0.075) = 410k ft^3
80 f 53% of outdoor air using grainger's 20" 8900 cfm whole house
75 f 63% fan for an average of 46 minutes per day, consuming about
70 f 75% 46/60x180w = 138 wh of electricity worth about 1.3 cents.
65 f 89%
62 f 100% where can we buy a "differential absolute humidistat"?
given a choice, we'd like to ventilate with cooler air in the summertime.