Filter Build Up

[Chris Stichter]

I did an inspection a couple of months back & the clients contacted the realtor because there has been a recurring build up of a black substance(soot like I'm guessing) on the filter which is located in the hallway ceiling of a single story home. The clients initially called an HVAC tech to identify. They were unable to figure out what was going on. Realtor in turn calls me for my thoughts, but I have never run into such a thing. According to the homeowners, they are having to change the filter weekly due to this condition. There is no fireplace in the home which was my first thought. Anyone have any experience with anything like this?

As always, thank you for your help.

Chris

[Markus Keller]

I've seen this at various homes. I have yet to find it to be due to a single cause. It is usually some of the following:
- pets
- return near open window or entry doorway
- home with open windows or doors and construction outside
- dirt coming into home not being cleaned up
- return grille near kitchen sucking kitchen smoke from cooking
- poor seal between duct/ceiling drywall/grille. If it is a dirty attic space and there isn't a good seal, the return can pull some dirt through and blacken the ceiling around the grille. (I managed to figure that one out because there was also some insul fuzz stuck along the grille)
That's all I remember for now.
Good luck

[wayne soper]

Crack house, candle burners,

[DavidR]

Rule out the obvious first, such as candles or are they smokers.

After that it might get into another level of testing to determine what the problem is.
It could be anything from building envelope issues to HVAC Installation issues.

[Jim Zborowski]

Are there alot of those oil filled plug in air fresheners present?
I have been in homes where they have 2 o3 in every room, they leave an oily film on everything, which of course in turn holds every particle of dust, loose pet fur, and anything else floating in the air.

[Chris Stichter]

Just to update in case someone runs into a similar situation...

I ran into the realtor and the homeowner finally admitted to her that she has been burning candles in the home. Phew...