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  1. #1
    Join Date
    Apr 2006
    Posts
    81

    Condensation On Plenum

    Is it normal for condensation to be on the outside of plenum in the attic. It was over 100 degrees in the attic and there was slight condenation on the output side of the blower.

  2. #2
    Join Date
    Jul 2008
    Location
    Alabama
    Posts
    658
    You mat have air leaks. Or missing insulation on inside of air handler. Only seen a couple sweat in attics. Both were foamed attics.

  3. #3
    Join Date
    Feb 2008
    Posts
    78
    How about on the plenum in a crawl space? Our new system has slot of condensation on the plenum. Is that normal?

  4. #4
    Join Date
    Jul 2008
    Location
    Alabama
    Posts
    658

    Yep!!

    Do you have a good moisture barrier??

    Does rain water get under the house???

    Is the crawl damp???

  5. #5
    Join Date
    Feb 2008
    Posts
    78
    Quote Originally Posted by superd77 View Post
    Do you have a good moisture barrier??

    Does rain water get under the house???

    Is the crawl damp???
    Yes, no, and not really.

    Maybe I'm dense, but just making sure - it is normal, correct?

  6. #6
    Join Date
    May 2007
    Location
    Upstate SC
    Posts
    188
    Is it sweating over most of the plenum, or just in a few locations? My old plenum portions (sheet metal, paper wrapped insulation) in the crawl space never sweats except where the insualtion is torn or loose. The new round flex duct the installer used to replace a portion of the plenum sweats over most of it. I have a vented crawl space, with a pretty decent moisture barrier on the ground.

  7. #7
    Join Date
    Jul 2008
    Location
    Alabama
    Posts
    658

    Is your crawlspace vented??

    Quote Originally Posted by richmod View Post
    Yes, no, and not really.

    Maybe I'm dense, but just making sure - it is normal, correct?

    Ducts sweat in crawlspaces in the south. May need to and insulation.

  8. #8
    Join Date
    May 2008
    Location
    CHICAGO IL.
    Posts
    79
    To Humid In Attic Call Technician To Look At Duct Work

  9. #9
    Join Date
    Jul 2008
    Posts
    33
    What is the temp. diff between the supply and the return. Coil could be too cold.

  10. #10
    Join Date
    Jul 2008
    Location
    Alabama
    Posts
    658
    Quote Originally Posted by cnpro18 View Post
    What is the temp. diff between the supply and the return. Coil could be too cold.

    The dude has a uninsulated plenum in a crawl, its gonna sweat regardless of coil temp.

  11. #11
    Join Date
    Jul 2008
    Posts
    33

    Angry

    Quote Originally Posted by superd77 View Post
    The dude has a uninsulated plenum in a crawl, its gonna sweat regardless of coil temp.
    Any uninsulated plenum in a non conditioned space is going to be creating a small flood, not just a little condensation. Sounds like it may be internally insulated and Mr. homeowner doesn't know any better. I've seen plenums sweat in conditioned spaces if coil is too cold due to some other problem.

  12. #12
    Join Date
    Feb 2008
    Posts
    78
    Quote Originally Posted by cnpro18 View Post
    Any uninsulated plenum in a non conditioned space is going to be creating a small flood, not just a little condensation.
    It's not just a little condensation - the whole plenum is covered with condensation, and there is actually a small pool of water under it now, though not a flood.

  13. #13
    Join Date
    Feb 2008
    Posts
    78
    Quote Originally Posted by cnpro18 View Post
    What is the temp. diff between the supply and the return. Coil could be too cold.
    Don't know - how would I measure it?

    Of coil is too cold, can that be adjusted on the AHU?

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