I am looking into installing a dehumidifier into a bedroom (~250 sq f?). Thus, I need it quiet, and I also would like it to be able to go down to 25% RH. Since the room is quite small I am hoping to find a unit that can do the job w/o making too much noise. But I am having hard time finding humidity range in specs for units sold online. Can anyone make a suggestion? Derby is advertised as the quietest, but it only goes down to 35% RH. I guess anything above 60 Db is noisy (Derby is 50 db).
Thanks a lot for the responses. Interestingly, I called EBAC, and they also recommended a dehumidifier based on a chemical absorbent.
I am trying to create a desert-like atmosphere in my bedroom. 25% is not that low: the air in mountain regions and deserts is much dier. E.g. the weather forecast in Bishop, CA for today claimed 13% humidity.My asthma gets much better in the desert and in the mountains.
In addition, I found that dessicant-based DHs generate excessive heat. In principle, I could make an exhaust system to drive the heat outside of my room... This way I could also avoid having to dump the water.
It's hard to do 25% in the usual way. Raising air from 32 F and 100% RH (with a frozen coil) to 70 F would only lower the RH to 24%...
... 150 Tyvek bags filled with desiccant clay can absorb 28% of their weight in water, ie 53 pints:
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The Florida Solar Energy Center puts clay bags on wire racks in an attic with a tin roof which heats up and dries them out during the day. After they cool, at night, they remove moisture from house air that circulates up through the attic. Here's some Desi-Pak (tm) tech info:
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Graph 4 shows Desi-Paks can absorb 12% of their weight in 10 hours at 30C and 60% RH, ie 2.3 pints per hour for the 189 pound collection above. This rises with more airflow or thinner bags. Graph 3 says they can absorb 8% in 100 hours at 25C and 10% RH, ie 0.15 pints per hour for 189 pounds.
Engineer Eric Zuercher at 800 995 5590 can email more regeneration info, eg a graph of clay capacity vs temp, about 17% at 90 F and 5% at 100 F and 2% at 200 F.
If Neon John gave a rat's ass about global warming :-) he might engineer himself a plastic film greenhouse full of bags to keep his valuable books dry, given an outdoor humidity ratio w = 0.0152 pounds of water per pound of dry air and average daily min and max temps of 67.7 and 89 F and 1860 Btu/ft^2 of sun on the ground and 710 on a south wall on an average July day (the worst-case month for dehumidification) in Chattanooga, with less water vapor pressure and cooler air up in his mountain hideout.
Since you know more about desiccants than anyone I know, do you have any information on calcium chloride and or lithium bromide (as liquid desiccants)? I'd like to take some of my excess solar heat and and use it to air condition.
Calcium Chloride dessicant dehumidifier diagram:
AC example:
I've been wondering where the balance is between humidity, temperature and solution concentration. My guess is this is where the enthalpy of the air = that of the brine desiccant, not that I know what the enthalpy of the brine is!
Roughly what I'm thinking of is using a combination of solar heated water (passed through a radiator) and hot attic air (I have a fan powered gable vent) to regenerate the desiccant.
I'm very comfortable with my own personal religion. I don't need to adopt your set of myths.
Yo Nick. Yoohooo, anyone in there? Lights are on but is anyone home? One more time, I don't live in Chattanooga. I live 100 miles away in a mountain-side dense forest. Mountain peaks extend for at least 1000 ft on either side of my. Sun only makes it into this little valley for a few hours a day even in the summer. To waste money on something like you suggest, I'd have to cut down the forest that surrounds my home. Why would I want to toss out all those pretty trees and natural shade?
Besides, the overwhelming proportion of my power comes from nuclear. The Ultimate Green Power Source.
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