View Full Version : HELP ME UNDERSTAND.
05-09-2006, 08:51 AM
TRYING TO CONTROL HUMIDITY IN MY HOME. I HAVE ALREADY ORDERED A ULTRA-AIRE 100V. IT WILL BE INSTALLED NEXT WEEK. IN THE MEAN TIME, TODAY THE HUMDITY OUTSIDE IS 86% AND THE DEW POINT IS 70 WITH A TEMP OF 74. I WAKE UP TODAY AND THE INSIDE HUMIDITY IS 64%. HOW DOEWS THE OUTSIDE HUMIDITY GET INSIDE MY HOME WHEN IT IS SUPPOSE TO BE A TIGHT HOUSE. IN FACT, THAT IS THE REASON OF THE DEHUMIDIFIER, OVERSIZED AC AND TIGHT COUNSTRUCTION. IM CONCERNED THAT THE ULTRA-AIR WILL DRY MY HOUSE THEN JUST PULL OUTSIDE HUMIDITY INSIDE?
05-09-2006, 12:00 PM
One lb. of moisture in a 1,000 sqft. space raises the %RH 8%. Here are some of the moisture sources inside of a Home:
1. Breathing+prespiration people produce approx. .25 lbs./person of moisture per hour depending on activity.
2. Cooking, bathing, etc.??
3. Infiltration of outside air into the home when outside dew points are higher than inside. 100 cam of 70^F DP, 110 gr. air adds 55 grains of moisture lb. of infiltrating air verses 75^F, 50%RH, 65gr desired. This is 3 lbs. of moisture per hour air that needs to be removed per 100 cfm of infiltration. Your clothes drier removes +100 cfm of air. Keep in mind that when the outdoor dew point is 40^F, 1.5 lbs./hr. of moisture is removed from your home by infiltration.
4. Diffusion of moisture through the outside walls/slab to the inside. Not much but adds up.??? This is the only source that will increase slightly as maintain proper indoor humidity.
There are plenty of sources
Typically 70-80 lbs, or 10 gals. of moisture need to be removed each day to maintain <50%RH in your home with +70^F outdoor DP. A/c removes 2-3 lbs. of moisture per ton per hour. On a hot day, a/c should remove enough water. On a cool day, a 90 pint/LB./day dehumidifier removes the moisture.
Regarding pulling in more moisture because of the home being dry, diffusion of moisture will increase when you keep your home dry. This is the smallest source of moisture and will not greatly affect humidity control. If this is not more info than you wanted to know, ask. TB
05-09-2006, 12:15 PM
cap-locks on internet-speak conforms with SHOUTING...
get with the P.G.
05-09-2006, 12:28 PM
Don't worry, the Ultra-Aire will do the job. An oversized AC contributes a lot to high indoor humidity. I had a 4 Ton unit that was so efficient it hardly ever ran (so removed very little humidity). I changed it to a 3 Ton so it runs more (and costs less to run), but still didn't get my indoor humidity less than 70%. I put in an Ultra-Aire and I easily keeps humidity below 50%.
The only problem I have with the Ultra-Aire is mold growth inside it. It's not easy to clean. I shut off my outside air intake and seems to help. Outside air here in Austin is full of mold and humidity, causing the dehumidifier to run a lot more than it needs to. I find the more it runs, the wetter it stay inside (the unit), and the greater chance of mold growth. A UV light inside might be a solution.
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