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  1. #1

    New HVAC installed, musty smell when heat is on

    From the very first day my new Lennox HVAC was installed at the beginning of 2009 there has always been a musty order coming out of the vents when the heat is on. The installers said it would go away, but it hasn't. Its a very strong smell and does eventually go away with constant use of the heater, however if I stop using the heater for a day and then turn it back on the smell comes back just as strong. I called the installer out to fix it just last month, but of course by the time they arrived the smell had gone becuase I was using the heater constantly.

    When the HVAC was installed they did not replace any of the duct work or the plenum. Is the plenum the problem?
    I suspect the musty smell must have something to do with water build up or condensation. Thoughts?
    I've also pour bleach down the drainage tube each month to kill any mold build-up but this has no affect on the musty smell.

    ALSO, the installer tried to save me money and let me in on the secrect of using mastic to sesl the plenum and all duct work joints. I'm starting to think its the mastic that is causing the issue. Thoughts?


    My system is as follows:
    Lennox G60UVH(X) Series Gas Furnace
    Lennox Elite Series XC14 Air Conditioner
    Ultra Violet light installed between the A-frame coils that is always on.

  2. #2
    Join Date
    Jun 2007
    Location
    Logansport, IN
    Posts
    20
    It might be coming from a dead mouse, or animal of some sort. I have never had mastic smell musty. You might look for a product called clean air, and put it in the return duct until the animal is dried up. Or have your ducts checked?????

  3. #3
    Join Date
    Sep 2004
    Location
    Oklahoma
    Posts
    83
    Is unit installed; attic, closet, basement, garage? Does the system have returns in each room or 1 or two big returns? Where is the return; ceiling, wall, floor?

    Lane

  4. #4
    This is a one story house about 1500 sqf. The unit is installed in its own closet in the hallway about two and a half feet up off the ground. The air return is located directly beneath the unit and there are two large vents roughly 34x22 inches on the walls at ground level. There is no blockage of the return air flow. I'm using a brand new merv 12 filter right now. There is a fabric type product they mastic-ed to the floor directly below the unit in the air return compartment that is supposed to be for sound deadening. Seems like it could retain water if it wanted too, but I checked and it is not wet and doesn't smell bad so I've ruled that out.

  5. #5
    Join Date
    Jan 2005
    Location
    Emerald Coast
    Posts
    933
    Does the "drain tube" pass into the return plenum at any point?

    Can you post picture(s) ?

    Where are you located?
    Do not attempt vast projects with
    half vast experience and ideas.
    ...

  6. #6
    Join Date
    Jan 2010
    Location
    Athens GA
    Posts
    1,234
    Whatb isd your source of heat.Is it elec,gas,,,,oil?.

  7. #7
    Here are the pics. I'm located in Hutto, TX. It's a gas furnace. The drain tube does indeed pass right through the return plenum.
    Should I insulate those tubes with something down there?

    Just for reference the previous hvac had never emmited a musty smell.
    Attached Images Attached Images     

  8. #8
    Join Date
    Jan 2005
    Location
    Emerald Coast
    Posts
    933
    A) I do not suspect the mastic.

    B) I do suspect you're drawing in sewer gas from somewhere.

    C) Don't under-estimate the new blower.


    Hope this helps.
    Do not attempt vast projects with
    half vast experience and ideas.
    ...

  9. #9
    Join Date
    Mar 2001
    Posts
    1,213
    Did you actually get a NEW 'A' coil?

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