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Community and Q&A

Aeroseal duct work

alcoaky | Posted in Energy Efficiency and Durability on

Had my hvac system aerosealed. The air return system had leaks equal to an 18 inch square hole. They sealed it until it was ok. The service ducts checked out ok,so they did nothing to it.. But I still have a terrible dust and filth problem. They unhooked the flex duct(which goes to the room vents) from the main trunk line and plugged the holes and checked it that way. Should they have sealed off the individual room vents and checked it that way instead of sealing off the lines at the main trunk line? The hvac system is about 2.5 years old.
I had the new hvac system installed(including furnace and all duct work). I ran the system for a total of 30 hours with no dust or filth. Then I had the white blown in insulation installed and every since then I have had the dust and filth problem. I am thinking that when the insulation was blown in, they may have knocked something loose.
I have sealed every hole or crack in the house. Even covered the light sockets and switches with foam inserts. The home was checked for leaks and it had a number of 1100 cfm and that was before I sealed everything up.
Any suggestion or help on my serious problem?

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  1. GBA Editor
    Martin Holladay | | #1

    We need more information.

    1. How often do you check your filter? Is your filter relatively clean or relatively dirty when you check it?

    2. If you check your filter and find that it is dirty, do you change it?

    3. Do you know the results of your last duct leakage test? (This is a number followed by the units "cfm @25 pascals.") To interpret this number, it's also useful to know the size of your house in square feet.

    For more information on this topic, see Duct Leakage Testing.

    -- Martin Holladay

  2. alcoaky | | #2

    Check my filter every two months. It is relatively dirty. The dust and particles are the same amount before and after I change the filter. I do not know the results of the leakage test. He just stated the main trunk line did not need any service. It was in fine shape. The returns had an 18 inch square leak and he got it down to 4 or 5 inches. I have 1680 square feet. 11 service lines and 3 return lines plus the 20 in sqqare return in the hallway.Sorry I don't have any info on the leakage test.
    Would the 30 hours of running the fan prove anything as far as leakage is concerned before the insulation was installed. After the 30 hours there was no dust or anything in the house. Like I said before, I am thinking that the insulation installer may have knocked something lose when he was doing his job. The hvac people checked the main trunk line but did not run the aeroseal through the flex lines that run to the vents in the rooms.

    Thanks for the info. Robert

  3. GBA Editor
    Martin Holladay | | #3

    It sounds like your forced-air registers are delivering dusty air immediately after you change the filters. If that's true, something is wrong. Either your perception is correct -- and the dust is coming from the registers -- or else your house is dusty for other reasons. (Housekeeping issues? Just speculating here.)

    Assuming the first of these two explanations -- the dust is coming from the registers -- you need to have your duct system evaluated by a home performance contractor. If you don't trust you Aeroseal contractor, hire someone else. Tell the contractor that you want a Duct Blaster test to check your duct system for leaks.

    -- Martin Holladay

  4. Anon3 | | #4

    Then I had the white blown in insulation installed and every since then I have had the dust and filth problem.

    Yeah, in a leaky house you'll pull it in. You need to air seal the attic, the wall, the electrical panels, everything. Check behind the dishwasher too. Every plumbing penetration, everything.

  5. GBA Editor
    Martin Holladay | | #5

    I'm not sure of the circumstances of the work you are describing. But the standard advice we give here at GBA is this: air sealing comes first, then insulating. If you can't afford to air seal, don't bother investing in insulation.

    -- Martin Holladay

  6. Anon3 | | #6

    Well, it's a bit too late for OP. Now he's fu.,cked.

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