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  1. #1

    Confused White dust is blowing from my HVAC system – Please help!

    I had a brand new McQuay Water Source Heat Pump (19K BTUs) HVAC unit installed in my apartment less than one year ago. It was fine during the summer when I was using the cooling. However, after I switched over to heating recently in November, white dust / flakes began blowing out of the unit. It is also accumulating at the bottom of the pan and in the coils. What a mess! The HVAC unit is enclosed inside a built-in cabinet with a vent at the top.

    The other unit (a different Climate Master older model) also enclosed inside a built in cabinet in another room in the apartment is fine. The installer has no idea what’s causing this in the new unit.

    What is this white dust? Any idea what’s causing it? How do I resolve this? Please help! It’s cold and I need to fix this ASAP!

    McQuay Model WMF – flat top unit: http://www.mcquay.com/mcquaybiz/lite...SHPConsole.pdf

  2. #2
    Join Date
    Aug 2006
    Posts
    112
    many thing can cause dust- pets, people, construction, etc.. sounds like something different is happening with your system. it is possible that the coating on the coil could be comming free or the cabinet paint flaking off. i had a deli case lose the coating on a coil and made quite a mess in the cabinet.

  3. #3
    Join Date
    Jan 2007
    Location
    Minneapolis, MN
    Posts
    415
    It sounds like scale from a water leak. I have seen a similar type situation with leaking humidifiers.

  4. #4

    Confused White dust is blowing from my HVAC system – Please help!

    I don't see anything flaking off from the cabinet or coils though...this happened to me 1 year ago on my first unit...i thought it was the unit so I had it replaced via warranty and now it happened again one year later after I switched from cooling to heating...

    any other idea why this is happening?

    your input is greatly appreciated!
    Last edited by bluexm; 11-27-2007 at 09:19 PM.

  5. #5
    Join Date
    Apr 2004
    Posts
    7,680
    Personally, I think it's a form of mold forming on the coil in the summer and flaking off in the winter when the coil is hot and dry. The mold didnt come with the unit, it grew there. If'n it were me, I would have the indoor coil thoroughly cleaned and add a UV light.

  6. #6
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,037
    Is there a humidifier on this unit?
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  7. #7
    Join Date
    Apr 2007
    Location
    Langley, BC, Canada
    Posts
    384
    Sounds like water scale build up, or mold, do you have adequate condensate drainage?. clean the coil really good with calclean, or another cleaning product, usually a cleaning product that doesnt require alot of water to rinse, you dont want to soak the inside of the unit.

  8. #8

    Confused White dust is blowing from my HVAC system – Please help!

    Is this a common issue? Is this water scale build up or mold dangerous?

    What does adding the UV light do? Where can I get it?

    How often do I need to clean the coils with calclean? If this a yearly cleaning that I should do whenever I change over from cooling to heating?

    Does the calclean product have a heavy odor? How can I get this?

    Can I do this cleaning myself or do I need to hire a professional to do this?

    Thanks!

  9. #9
    Join Date
    Apr 2007
    Location
    Langley, BC, Canada
    Posts
    384
    Mold can be a health issue yes, water scale, not so much. A UV filter will kill mold spores in the air, the work very well 99.9%, you can get them from your local A/C contractor.
    Coils should be cleaned usually once a year, depending on how bad your coils are, the dirtier they are, the more frequent you nead to clean.
    The product I use is called evap foam, it comes in an airesol can, has a scent of lemon. I'm not sure if you can purchase it yourself from an A/C supplier. Wear gloves and watch for any back spray, it will iritate your skin. Requires no water to rinse, it will naturaly wash away, make sure you do this will it is off, and run it in the cooling mode ONLY.

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