Condensation on duct work
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  1. #1
    Join Date
    Jul 2005
    Posts
    2
    We have a half crawlspace/half basement that is finished. The ductwork in the crawlspace area is exposed so we can see it. We notice there is alot of condensation on the bottom side of the ductwork, not dripping, but more like sweating. Is this normal or should we be concerned?
    Any suggestions?

    The ductwork is already insulated on the outside and its there where the condensation is occurring. It also has some kinks in it in places. Would this contribute to the problem>

    [Edited by thebirm on 07-25-2005 at 06:42 AM]

  2. #2
    Join Date
    Jul 2005
    Posts
    14
    I would suspect that there is no insulation lined inside the duct. Have the outside "wrapped" with insulation to avoid a slow corrosion process of the metal.

    This will continue to happen if not wrapped. "Think" cold can of beer brought outside in a humid environment = cold metal ductwork in a humid crawlspace.

  3. #3
    Join Date
    Feb 2005
    Location
    Central Alabama
    Posts
    466
    maybe low airflow

  4. #4
    Join Date
    Dec 2004
    Location
    Derby City
    Posts
    3,958
    Here, code requires that ductwork in non-conditioned space such as crawlspace has to be insulated. Otherwise, you get the humidity condensing on the cold metal surface of the duct. Moisture problems in crawlspace as well as deterioration of the ductwork. This duct may be grandfathered, but you should still do the insulation. If the system is operating all right otherwise, insulation of the ductwork is the appropriate step to take.

    If in doubt on the operation, call a professional. p.s. they can probably checkout the sytem and do the insulation of the duct for you as well. 2 birds....one stone.
    Everyone has a purpose in life..........even if it's to be a bad example.

    Seek first to understand, before seeking to be understood.

  5. #5
    Join Date
    Jul 2005
    Posts
    2
    Forgot to mention the duct work is flexible tubing with an encapsulating insulation layer. It is running through a structural truss joist system and the ductwork is pinched and compressed multiple places in the 18' run through the crawlspace.

  6. #6
    Join Date
    Jul 2005
    Posts
    14
    Why is it that "Flexduct" and "Problem" always seem to meet eachother in a dark, damp alley?

  7. #7
    Join Date
    Apr 2004
    Location
    NJ
    Posts
    155

    Cool

    Sounds like the actual duct (the "spring" part under the insulation) is broken or torn.

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