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Thread: A/C In attic?

  1. #1
    Join Date
    Mar 2005
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    I have a question not sure if anyone can answer but here goes. I live in New Hampshire warm summers and cold winters. I have seen a couple a/c split systems with the air handlers in the attic and the duct work has water in it in the winter. I assume it is condensation but all duct work is insulated and it will be in random ducts. Any answers to the reason this happens, or suggestions on fixing this.

  2. #2
    Join Date
    Nov 2004
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    Thibodaux, LA
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    In the winter your attic is cold and the inside of your house is warm. Not only is it warm, but it is humid. Why?
    I am sure New Hamshire winters get pretty uncomfortable. This keeps you in the home more and your body releases moisture when you breathe and sweat. You put moisture in the air when you cook (boil water). When you bath or shower you increase the humidity in your home. The warm humid air moves up through your duct system and condenses on the cold wall of your ducts. Check your Furnace or Fan coil cabinet you probably have water in there also.

    Although I am not from your area, I have experienced similar problems in my area.

    As for fixing it. There are many options. Try running the fan on constantly. Replace the ducts with ducts with a higher r-value. Dehumidifier. Fresh air from outside.
    Don't cook, bath or shower. Breath through a pipe with a small crack in the window. Just jokin

    Hope this helps

    [Edited by bluetooth751 on 03-09-2005 at 09:42 PM]

  3. #3
    Join Date
    Mar 2005
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    34
    up here the house is a lot drier in the winter there is not a lot of humidity. Also the ducts that have water aren't always the ducts closest to the bathroms or kitchen, its strange.

  4. #4
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    Mar 2005
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    burlington county n.j.
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    house may be dry but warm air is still migrating up into ducts and causing the problem. try closing registers or adding insulation to ductwork.

  5. #5
    Join Date
    Mar 2004
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    NJ
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    Originally posted by bluetooth751
    In the winter your attic is cold and the inside of your house is warm. Not only is it warm, but it is humid. Why?
    I am sure New Hamshire winters get pretty uncomfortable. This keeps you in the home more and your body releases moisture when you breathe and sweat. You put moisture in the air when you cook (boil water). When you bath or shower you increase the humidity in your home. The warm humid air moves up through your duct system and condenses on the cold wall of your ducts. Check your Furnace or Fan coil cabinet you probably have water in there also.

    Although I am not from your area, I have experienced similar problems in my area.

    As for fixing it. There are many options. Try running the fan on constantly. Replace the ducts with ducts with a higher r-value. Dehumidifier. Fresh air from outside.
    Don't cook, bath or shower. Breath through a pipe with a small crack in the window. Just jokin

    Hope this helps

    [Edited by bluetooth751 on 03-09-2005 at 09:42 PM]

    Not enough information was given as to whether the a/c system is seperate from the heat. If it is forced air gas/electric in the airhandler then yes a lack of insulation on the duct could be responsible.

    Radiator heat cranked all the way up should dry up the Atlantic in a week lol.

    It could just be mouse pee too.


    But I will take a wild guess of what is going on.

    The a/c system is seperate from the heat(i.e. baseboard/radiator/radiant floor)

    The a/c duct vents are not closed by the HO like they should be in the winter.

    Ok in the winter there is a lot of humidity but its frozen.

    but when you walk in and your boots, coats, even sweat etc "dry out"

    what is happening is the heat in the home is evaporating the water molecules and they become less dense and of course rise with the heat.

    In to the open a/c ducts in the attic.

    The colder temperature of the ducts in the attic then causes
    the water vapor molecules to condense back to water inside the duct.

    Its like boiling off water and then trapping the steam in a refrigerator.

    I would suggest closing the vents and sealing the inside of the return with plastic during the winter if it is two seperate systems.


    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  6. #6
    Join Date
    Jun 2001
    Posts
    161
    The duct insulation is probably R-4. Not that great but typical. Also the takeoffs and such may not be covered real well. Are the dampers in the registers open or closed? Some will say that usually there is more problems when the dampers are closed. Because the typical dampers don't close real tight the humid warm air still migrates up into the attic ductwork. There it sits and condenses. If the dampers are open you may have enough natural air flow to prevent condensation. Running the fan will solve the problem but nobody wants to do that. Depending on the programmable tstat you could set the fan to run a hour a day while they are away.

    brent

  7. #7
    Join Date
    Mar 2005
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    All the vents are closed but they aren't air tight. I guess that the only way to solve it may be to completely seal vents off, but the we will have to go back every year, not good. It is just a/c the heat is baseboard, any other solutions?

  8. #8
    Join Date
    Dec 2004
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    nope!! seal supply registers and return grills

  9. #9
    Join Date
    Jun 2001
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    161
    Try opening the dampers wide open. The natural convection may be enough to prevent the ducts from condensating.

    brent

  10. #10
    press1 is offline Professional Member BM -bad email address
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    Move to California!

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