 Posted 12/27/2005 3:51:04 PM
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| I have a 10 year old house in New engalnd. and during the winter months i get alot of condesation in the attic. I recently found that i have water( about 2-4 cups) in the ducts coming from my trunk line in the attic that lay on the attic floor. also noticed that small ice balls form on the nails on the attic roof. the house is 2100sq/ft and 2 adults and 3 kids with 2 baths upstairs with shower/bath both with exhaust vents. how can i prevent this from happening????
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Posted 1/2/2007 5:40:40 PM
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| I assume the humidity inside the home is normal, as your windows are not sweating? Warm moist air from your home is being cooled below the air's dew point, condensing the moisture on the cold surfaces. You must stop the moist air from contacting the cold surfaces or warm the cold surfaces. If the ducts are for a/c, seal the grills during winter stoping house air from entering the ducts/attic. If ducts are for heating, better insulate your ducts with a a vapor barrier on the wet side and operate the fan often enough to avoid duct surface cooling. Occasional frost on nails is not serious. Increased ventilation with outside dry air lowers the dew point of the attic air. Keep us posted on the resolution of this difficult problem. Ken
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Posted 1/2/2007 5:40:40 PM
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The humidity varies as i also run a dehumidifier in the hall upstairs, and this helps with the windows not sweating which was occurring without the dehumidifier. I have had all the flex ducts and the truck line emptied of water on Friday. These vents are only used for AC and i do close the grills in the ceiling in the winter should i be covering them also?? I also block up the return in the hallway upstairs. It is still very confusing for me and the AC guy of why all the water was in the ducts and the trunk line.Should i leave the grills in the ceiling open to let the warm air up to the vents in the attic and prevent them from getting to cold?? We do access the pull down stairs to get in the attic very often 1-2 times a week for storage, does this have anything to do with it?? Still a bit puzzled.
Thanks
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Posted 1/2/2007 5:40:41 PM
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You have a problem with too much moisture or not enough fresh air ventilation in your home. Crawlspace without a moisture barrier on the earth, high water table under your home , or a small plumbing leak may release extra moisture into your home are water source problems. If you have a operating humidifier, it should be off. More occupants also contribute to high humidity.
Operating an exhaust fan discharging moist air out of the home and not into the attic is the ideal method of drying a home during the winter. Totally seal all registers, returns and supplies keep the moisture from the inside of the ducts to avoid condensation.
Typical dehumidifiers are not effective at reducing %RH during winter weather. A minimum fresh air change is the most effective method to control indoor %RH during cold weather. If you have bathfans, operate them continuously until the windows dry. It maybe necessary to operate the bath fans continuously during cold weather. The slight negative pressure will also slow moist air movement into the attic. This is a common problem in air tight homes. Ken
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