Sizing a Humidifier/Dehumidifier

[dixie2005]

How do you size a humidifier? Once RH is determined for the conditioned space, can find grains of moisture from psych chart...then what?

How about a dehumidifier? The opposite?

Thanks!

[smokin pat]

The answer your looking for in in the design information of the device. Design per square foot in specific conditions.

[gcollins]

WHAT ABOUT VOLUME. ?
I THINK A 6FT CRAWL SPACE HAS ABOUT 3X THE VO:p LUME OF A 2FT CRAWL

[300 Win Mag]

I'm also interested in any info, I have a place with about 150 tons of air I have to Quote humidification in.

[Thrillho]

Use the equation

m=4.5(scfm)(w2-w1)

Where:

m= moisture removed or added (lbs)
w=humidity ratio (from psych. chart lb of moisture/ lb of dry air)

[teddy bear]

Volume of the space does not work. You need the air change rate on the space and the moisture generated in the space. Humidification or dehumidification is based on the amount of air change, the moisture content of the make-up, and the desired moisture level in the space. Example assuming no space load:
150 cfm of 70^F dew point, 110 grain make-up air
75^F, 50%RH, 56^F dew point, 66 grains
(150 cfm/14 cf/Lb) * (110 grains-66 grains)/lb air * 60 min/hr =28,285 grains of moistue/hr
28,285 grains/7000 grains/lb=4 lbs of moisture per hour removed or added= 4,200 btus latent.