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re: humidifier filter suggestions requested
26 oct 2003
sewmaster wrote:
>now for the sticky part: the filters on these things have to be
>replaced monthly due to the very high iron content in the water here;
they might need replacing less often if the water comes from and returns to
a toilet tank in which periodic flushing reduces the iron concentration.
you might make an interesting fountain sculpture above a tank (a large
collection of wet nylon stockings hung from plastic coathangers?) with
harbor freight's $9.99 11 watt fountain pump in series with a humidistat.
then again, if a typical 2400 ft^2 house leaks 1 air exchange per hour,
that's 1x2400x8/60 = 320 cfm, about 10x more fresh air than the ashrae
requirement. heating it from 30 to 70 f without humidification takes about
40x320 = 12.8k btu/h, about 3 gallons of oil per day in wintertime.
a pound of air at 50% rh and 70 f contains about 0.0078 pounds of water,
vs 0.0025 pounds of water in outdoor air on an average january day near
phila, and a cubic foot of air weighs about 0.075 pounds, so humidifying
320 cfm of air leakage requires evaporating 60x320x0.075(0.0078-0.0025)
= 7.7 pounds of water per hour, which requires another 7743 btu/h of heat,
ie another 2 gallons per day of oil.
then again, turning the thermostat down 2 degrees f might save 24h(70-68)400
= 19.2k btu, about 0.2 gallons of oil per day. a green plant can evaporate
about a pound of water per day, so you might humidify all this air with 185
large potted green plants or an interesting 8'x8' indoor greywater swamp.
alternatively, you might seal up the house until it only leaks 30 cfm, and
humidify that air with the incidental 1 gallon of water per day evaporated
by 2 people in residence plus 9.325 large green plants, and save the heat
equivalent of about 5 gallons per day of oil.
last time i mentioned this in mcfl, 83 people jumped on me saying that dry
indoor air is unhealthy. i'm not saying it isn't, just suggesting air leak
reduction before wholesale humidification. then again, it's still more frugal
to humidify indoor air with personal mufflers, or those steaming harmonica
holders the star trek creatures wore under their noses. and many earthlings
simply adapt to dry indoor air in the wintertime.
nick
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