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  1. #1

    Is Duct Board A Safety Hazard

    Hi all,

    I have a question about duct board. I have been in the hvac field for three years as a service tech. I come across a lot of homes that have the duct board plenum's installed. These contain fiberglass internally. Several different techs have told me that this fiberglass comes loose when the system is on. They say that the homeowner is breathing this fiberglass and that it gets on the surface of the furniture etc. Is this a true claim or just a scare tactic to get the customer to spend money?

  2. #2
    Join Date
    Mar 2005
    Posts
    997
    Duct board will erode just like liner. Both of these can be coated to keep it from eroding.

  3. #3
    Join Date
    Dec 2006
    Location
    Tidewater VA
    Posts
    93
    The answer depends on a couple things. The age- like DRK said, air erosion over a period of time can wear down the factory sealed surfaces allowing fiberglass particulate to enter the air stream. The install- so long as the ductboard wasnt hacked in, chances are pretty minimal to fiberglass settling on furniture and in homeowners lungs (though if it was myself I would encapsulate it for GP) I see this alot in the field and encapsulation is mandatory for us after cleaning any fiberglass ductboard or liners to "re-surface" the interior of trunklines or plenums as this pre-sealed surface has been compromised by the cleaning.

  4. #4
    Quote Originally Posted by sm831 View Post
    The answer depends on a couple things. The age- like DRK said, air erosion over a period of time can wear down the factory sealed surfaces allowing fiberglass particulate to enter the air stream. The install- so long as the ductboard wasnt hacked in, chances are pretty minimal to fiberglass settling on furniture and in homeowners lungs (though if it was myself I would encapsulate it for GP) I see this alot in the field and encapsulation is mandatory for us after cleaning any fiberglass ductboard or liners to "re-surface" the interior of trunklines or plenums as this pre-sealed surface has been compromised by the cleaning.
    I have seen returns in the ceiling sealed with mastic. If you have a duct board supply plenum or spider boxes how would you seal these without tearing them up when you cut into it. I saw someone try this once it it was not worth the hassle. We ended up using a metal plenum and metal wyes.

  5. #5
    Join Date
    Feb 2006
    Location
    Float'N Vally, MS
    Posts
    1,879
    Quote Originally Posted by digital686 View Post
    Hi all,

    I come across a lot of homes that have the duct board plenum's installed. Several different techs have told me that this fiberglass comes loose when the system is on. They say that the homeowner is breathing this fiberglass and that it gets on the surface of the furniture etc.
    My take on this (usual disclaimers apply and in the state of Cali for nia this can cause cancer), older ductboard (+10 years) YES.
    Older ductliner also YES.
    Newer ductboard (last couple of years especially) is coated on the inside and is made of "longer" fibers that resist blowing loose. When first installed there will be some loss fibers that blow into the air, but that will calm down with use. Also the homeowner will not properly replace his filters and the dust/dirt will coat the walls of the duct and further prevent the fiberglass from coming loose.

    Exceptions to this are:

    1) The homeowner throws a lot of crap in the attic on top of ductwork and squishes it. This breaks the protective barrier.

    2) Untrained duct cleaning people poke, gouge and scrap the innards of ductboard. This breaks the protective barrier.

    2) Unprofessional workers (not HVAC people) try walking across the attic and fall spread eagle on the ductwork. (See #1 for results)

    This is why we are expanding our metal shop (metal wrapped on the outside)to help the customers (and those who move from Cali for nia) who are concerned with this.


    Life is too short, Behappy!
    TFMM

  6. #6
    Join Date
    Dec 2006
    Location
    Tidewater VA
    Posts
    93
    Quote Originally Posted by digital686 View Post
    I have seen returns in the ceiling sealed with mastic. If you have a duct board supply plenum or spider boxes how would you seal these without tearing them up when you cut into it. I saw someone try this once it it was not worth the hassle. We ended up using a metal plenum and metal wyes.
    All of our encapsulation is done using an airless sprayer, (a TITAN 440i to be exact), the spray nozzle can fit into an access opening as little as 5 in., and still provide a good even coating in all corners, crevices- its a great rig, Id love to have my own, as far as the hassle, its very little not sure which method you have seen done, I seen guys try to "paint" the sealer on with brushes which looked to be more aggravation than it was worth.
    Last edited by sm831; 11-26-2007 at 12:21 AM. Reason: the 400i doesnt exist.... yet

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