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Insulating round ERV ducting, foil faced foam, bubble wrap or fiberglass/

MSSUSR9501 | Posted in Energy Efficiency and Durability on

Finally got the ducting for the ERV installed.  Now looking at insulating ducts between ERV and outside wall for both inlet and exhaust.

I see that the foil faced bubble wrap is a very poor insulator and an older article characterizes it as “snake oil”.
I also see foil faced foam advertised as R8.
Working with this stuff is more appealing that the fiberglass sleeves.  Does it really work?
It seems some companies advertise R8 while others simply brag about high thermal reflectivity.  How to find the real info for these products?
What is going to be the best bet to wrap my 8″ round ducts?

I have about 30 linear feet to insulate.  My attic is conditioned space.

Thanks for any comments

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  1. Expert Member
    AKOS TOTH | | #1

    The simplest is standard fiberglass sock. Most fiberglass is around R3.7/inch, so you can always get the actual R value by measuring the thickness. If you want more R value, you can get a 2nd larger sock to go over the first one.

    Make sure to seal the foil along any seams and at the ERV and wall cap. You need the sock air tight as any moisture that makes it in there can condense on the cold duct and cause it to sweat.

    Bubble wrap is a waste of money, R2 at best. Trying to wrap it in rigid insulation is way too much work for not much benefit.

  2. Expert Member
    KOHTA UENO | | #2

    There are multiple GBA columns on bubble wrap insulation--it's about R-1 or R-2. If that's enough for what you need to do (e.g., avoid condensation), it might work, but it's not much R-value.

    Is Bubble Wrap Duct Insulation a Good Idea?
    Although reflective layers can be effective when installed correctly, they aren't the best way to insulate ducts

    See infrared image in Comment #7.

    Stay Away from Foil-Faced Bubble Wrap
    This R-1 product can be used to make Halloween costumes, but should never be used as insulation

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