What cause the white residue on this duct?

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1

Originally Posted By: ssopha
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http://www.nachi.org/bbsystem/usrimages/D/DSCN9516.jpg ]

2

Originally Posted By: ssmith3
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After zooming in on the little picture I can see a 10-12" round duct directly on top of that location. Where does that (round duct) run to?



Pretty good chance you are on the right track.

–
Scott Smith


Marinspection


Vice President NorCal NACHI Chapter


I graduated from collage. Now my life is all mixed up.
3

Originally Posted By: rlind
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That white, powdery residue is caused by incomplete combustion forming a moisture that leaks back to “collection points” as elbows and connectors in flue vents. I have some of that stuff on both my boiler flue and my natural gas fired furnace flue right now.


EVENTUALLY, this can cause the affected area to rot and cause a carbon monoxide leak. Be sure to check the integrity of the flue at all visible points where you find this residue.

Thanks,

Ron Lind
Solid Foundation Home Inspections, LLC

4

Originally Posted By: phinsperger
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I think Scott is on that right that it appears to be coming from above. The opening cut in the ceiling drywall may have left some gypsum powder on top of the square supply duct. Possible condensation from the round duct above slowly mixing with the gypsum dust?

–
.



Paul Hinsperger
Hinsperger Inspection Services
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