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  1. #1
    Join Date
    May 2008
    Location
    Berkshires MA
    Posts
    326

    Condensation on walls around Fan coil unit

    --------------------------------------------------------------------------------

    Hi
    I'm having a problem with the paint on the walls around my chill water fan coil units bubbling and the plaster behind the paint crumbling.

    These are Trane single pipe Hot water / Chill water fan coils installed in 1968. For the most part they are good running units.
    There mounted on out side walls under the windows.
    The BLDG is a brick face with cinder block and then plaster.

    In the last few years we've stared to have this condensation problem. There are holes in the Block for the pneumatics hole size is about 1-2" these hole have been there since 1968.

    I tried putting a thin sheet of plastic wall behind the units thinking it some kind of infultration problem but that didn't work.

    My boss thinks it the age of the unit, I don't see how that could be cause nothing has changed on them.

    I still think it some kind of infultration problem. But I can't figue out why.

    If any one wants to give me there please do.
    I used a little PFM to fix it.

  2. #2
    Join Date
    Oct 2009
    Location
    Murfreesboro, TN
    Posts
    108
    Does the surface of the wall stay cold near the air handler. Cold enough to be below dew point during the summer? The problem could be surface condensation due to the low surface temperature and elevated humidity in the space around the air handler. You have to increase the wall temperature, insulated the housing or lower the humidity to stop it.

  3. #3
    Join Date
    May 2008
    Location
    Berkshires MA
    Posts
    326
    Name:  3N Fan Coil Condesation 001.jpg
Views: 194
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    Name:  3N Fan Coil Condesation 002.jpg
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    I used a little PFM to fix it.

  4. #4
    Join Date
    Jul 2011
    Location
    Northern VA
    Posts
    8

    Talking Have you tried this

    Add a return in that room to circulate the air, drop the humidity. Woody

  5. #5
    Join Date
    Oct 2009
    Location
    Murfreesboro, TN
    Posts
    108
    This looks like an uninsulated pipe in the wall problem, but I can see that everything comes from the slab. I can even see the uninsulated condensate line going into the floor. Is there a possibility that the outside air intake duct is channeling rain water behind the unit and keeping the wall wet?

  6. #6
    Join Date
    Nov 2001
    Location
    Seattle, WA
    Posts
    7,814
    It's most likely a building construction/outer wall problem. I'm guessing this is on an outer wall, no insulation, no outside vapor barrier, leaking air currents inside the wall, etc, etc.

    Only way to know is open the wall and take a look. I'm bettin you are not going to like what you see...probably some timbers even rotted out.
    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

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