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Thread: Duct insulation

  1. #1
    Join Date
    Jan 2007
    Posts
    54

    Duct insulation

    Has anyone used a product called Reflectic duct wrap. Reflective silver on both sides with bubble wrap insige says has R value of R8. Can this also be used on main trunk on outside even though has insulation on inside. I,ve been having problem with duct sweating espicially main trunk. All duct runs thru crawlspace. I know between the humidity and the cool on main truck it will get some condensation but this stuff is supposed to stop the sweating?


    Thanks

  2. #2
    Join Date
    Jan 2010
    Location
    new orleans
    Posts
    230
    ive used it to help with condensation and was sucessful... on the other hand it only has an R value of 8 when wrapped properly ... Not to tight not to loose... much rather 2" duct wrap and be done with it..

  3. #3
    Join Date
    Jul 2010
    Location
    Maryland
    Posts
    35
    The bubble duct wrap insulation (I call it ) has an R value of R-4 in one layer. R-6 two layers. and R-8 2 layers with an air space between the layers. To achieve R-8 its easer with regular duct wrap. Your ducts are probably sweating where it is strapped to the floor joists which compress the insulation and diminish the R Value.

  4. #4
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190
    I guess I have been around too long to believe that the bubble wrap is really the R Values published. If it is effective it is because you have really sealed it and kept the air from getting to the cold duct surface and not because it is doing the same job that traditional fiber glass would.
    Call me a skeptic
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  5. #5
    Join Date
    Feb 2007
    Posts
    999
    I used it to decrease the heat pouring off of my main trunk, due to slow airflow (modulating furnace). I used single wrap with 3/4" airspace (R6). Before wrapping, I tested all seams and joints for leakage and sealed any offenders.

    During heating, when placing my hand several inches below the wrap, I feel little or no heat coming off. Air temperature at my farthest register has increased several degrees.

    Amp

  6. #6
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    I would look into whether that bubble wrap material claims additional R-value because of its silver coating. Because many ducts already have silver coating to begin with, and I know of no other product which can truthfully claim large R-value just because of capturing a quarter inch air gap.

    May I ask if the condensation is originating on the exposed surface of the duct, or somewhere inside the existing insulation. I am a homeowner but think I understand the problem. Sealing off humid outside (crawlspace) air so it cannot touch the cool duct, will solve some condensation problems, it is the air sealing rather than the R-value which deserves most of the credit for that.


    Best of luck -- Pstu

  7. #7
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190
    Take a piece of bubble wrap and use a lighter on the corner and see what happens.
    I don't think it is safe or as someone has already pointed out may bbe taking credit for it's shiny surface. (wonder how long it remains shiny)
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  8. #8
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,170
    buy R-8 duct wrap, mastic seal all leaks before insulating.
    then install duct wrap.
    I don't have much faith in foil bubble foil products &
    wouldn't recommend something I would not use.

    best of luck
    The cure of the part should not be attempted without the cure of the whole. ~Plato

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