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  1. #1
    Join Date
    Nov 2018
    Location
    Quebec, Canada
    Posts
    19
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    Duct liner -- good or bad?

    One Lennox HVAC contractor told me he prepares all his ducting with noise insulation liner in his shop before they're brought home for installation. I didn't ask for more details, so I don't know what type of liner he's using.

    And yesterday, I met with a Daikin HVAC contractor. I asked him about noise insulation (linear, etc.) and he was very reluctant to do it, unless I would insist (because of potential mold, fiberglass airborne air particles, etc.). He seems to mean (without clearly saying it) that he can avoid most noise by clever installation of ducting (proper angles, etc.).

    I searched online, ... and no duct liner scars me. But at the same time noise scares me too!

    My current system certainly has no liner, and it's not so bad. But it's a PSC blower at 850 CFM (2-ton AC). I suspect a new HP system with ECM blower will produce more airflow, so I'm worried about noise.

    Can someone explain what noise problem I can have if I don't use liner? And are there safe liner product that can be installed? Or other safer alternatives?


    Thanks,

    Larry.

  2. #2
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,873
    Post Likes
    Quote Originally Posted by LarryMTL View Post
    One Lennox HVAC contractor told me he prepares all his ducting with noise insulation liner in his shop before they're brought home for installation. I didn't ask for more details, so I don't know what type of liner he's using.

    And yesterday, I met with a Daikin HVAC contractor. I asked him about noise insulation (linear, etc.) and he was very reluctant to do it, unless I would insist (because of potential mold, fiberglass airborne air particles, etc.). He seems to mean (without clearly saying it) that he can avoid most noise by clever installation of ducting (proper angles, etc.).

    I searched online, ... and no duct liner scars me. But at the same time noise scares me too!

    My current system certainly has no liner, and it's not so bad. But it's a PSC blower at 850 CFM (2-ton AC). I suspect a new HP system with ECM blower will produce more airflow, so I'm worried about noise.

    Can someone explain what noise problem I can have if I don't use liner? And are there safe liner product that can be installed? Or other safer alternatives?


    Thanks,

    Larry.
    What will be the size of the HP? Is the HP a 2-stage model? EMC blowers are great but can be noisy on restricted ductwork. Don't be afraid of lined duct. The other contractor just doesn't want to do the lining so he's knocking it.

    It's unlikely you need lined duct, but it depends on the size of the HP and where the furnace/air handler is located.

  3. #3
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    17,078
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    Noise comes from undersized ducts not lined or unlined. yes there debates about fiberglass getting air born, if your concerned then insulate on the outside.

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