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  1. #1
    Join Date
    Sep 2005
    Location
    Texas
    Posts
    2,793

    mold and/or mildew on registers

    Ive got a customer that has mold or mildew growing on the supply registers so I get in the attic and find open cell foam blown in even around the boots so there doesnt appear to be any vapor barrier. I could cut out the boots and redo them but its also two story house so access is a challenge.

    Have any of you guys had any experience with this?

  2. #2
    Join Date
    Jun 2005
    Location
    The Gray Northwest
    Posts
    661
    I'd check air flow first, drain pan and indoor coil. Sounds to me like you've got moisture carry over from the evap coil.

  3. #3
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,281
    If the register face is growing mildew, it is because the register face is below the dew point of the conditioned room. Remember, room air mixes with supply air right at the register face, and not all of the register face is affected by supply air, other than the temperature of the air cooling the metal. You're probably seeing a heavier buildup of black stuff around the register's edges vs. the blades, but no matter...sounds like the airflow for the system may be a bit low, and/or it isn't keeping up with moisture infiltration/generation into the home.

    Concentrating on insulating the boot on the attic side helps assure no sweating of the boot in the attic. The register face will need to be held above room air dew point to avoid creating an environment moist enough to encourage mold/mildew growth.

  4. #4
    Join Date
    May 2008
    Location
    North Texas
    Posts
    105
    What the other gents have posted.

    If you pull the register, there may be no black stuff in the duct itself. Then it's simple enough to clean the registers with anti-mold or dilute bleach.

  5. #5
    Join Date
    Sep 2005
    Location
    Texas
    Posts
    2,793
    I suspect the humidity may be high in the house due to the lack of vapor barrier throughout. I dont think its the grilles as much so as the boots. from the attic side the flex duct is soggy wet, Im sure thats from the boots sweating. the systems are Trane 19i VS.

  6. #6
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,255
    What is the temperature and %RH? Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

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