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1989gta 09-05-2012 05:54 PM

white or clean dust
I'm helping a neighbor try and solve this issue that is plaguing her house.
About 2 months ago here in MN she started noticing white dust forming at an alarming rate. Her house is a rambler with a partially finished basement. There is one cold air return and one register down stairs and the dust seems to be isolated to the main level.

-She has had no construction
-No mechanical replacements.
-No new furniture or drapes installed.

She had her ducts cleaned about a month ago hoping that would help.

Here are a few photo's of the dust.

user1007 09-05-2012 06:34 PM

Weird it is making it past the filters.

beenthere 09-05-2012 06:48 PM

Moved to HVAC forum.

1989gta 09-05-2012 06:54 PM

It was going through the blue filters so she switched to the pleated 3m, ill check in a week. I would expect to see some build up. Also its not sheet rock dust it has no smell or taste.

allthumbsdiy 09-05-2012 07:19 PM

I am experiencing the same problem with the exact same "dust".

I think I isolated my problem to leaky panned returns. The condition of my panned returns were not that great to begin with, but a duct cleaning company made them worse when the guys punched holes on the end caps to stick in their air compressor nozzles. Some end caps were crushed in so badly that the gap between it and the main return was more than 1" wide, resulting in sucking in dirty air from the un-finished side of my basement.

They also might have done a shoddy job of cleaning, especially if they did not use air whips or brushes, possibly loosening up caked dirt that is now breaking apart in the vent.

I would check for any large gaps in the return side and foil tape over them if necessary for now (I will be replacing my end caps with new ones and use mastic to seal them).

I would also run the blower fan at full blast for 24/7 for about a week while frequently changing the filter (I went through three 4" media filters in that time period).

Good luck

Marty S. 09-06-2012 06:11 AM

I see that a lot on homes that had ducts cleaned. It's drywall dust from construction that was solid until the brushes loosened it up. The good news is it goes away in about a year.

how 09-06-2012 11:07 AM

Marty's probably right on this but ask your neighbour if she had that dust problem before she had the ducts cleaned?
Also check if that same white powder is on the floor around the furnace. Some venting precipitate can get that bad on poorly designed chimney vents when combined with leaking return air/ filter slot covers/furnace blower doors/ etc.

1989gta 09-06-2012 05:05 PM

The problem showed up a month before the duct cleaning, she had that done thinking it would help it did not. I'll have to look at the chimney.

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