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  1. #1
    Join Date
    Jan 2008
    Posts
    196

    Duct insulation...

    The duct insulation I want to have installed is in 5ft. by 25ft. rolls. It has a reinforced foil face and is a 2" cotton based product.

    I had a tech comment that it would be very difficult to install. Am i missing something here, why would it be any more difficult than fiberglass?

    Would you not just measure the circumfrance of the metal duct, cut it with a slight overlap on the foil facing and duct tape? Is duct tape good enough for this purpose or should I be requesting some other kind of product at the seams?

    Any insight would be great.

  2. #2
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quote Originally Posted by mlo1 View Post
    The duct insulation I want to have installed is in 5ft. by 25ft. rolls. It has a reinforced foil face and is a 2" cotton based product.

    I had a tech comment that it would be very difficult to install. Am i missing something here, why would it be any more difficult than fiberglass?

    Would you not just measure the circumfrance of the metal duct, cut it with a slight overlap on the foil facing and duct tape? Is duct tape good enough for this purpose or should I be requesting some other kind of product at the seams?

    Any insight would be great.
    Mastic would be better.

  3. #3
    Join Date
    Jan 2008
    Posts
    196
    Quote Originally Posted by dash View Post
    Mastic would be better.
    Dash, mastic over the seams of the insulations foil face?

    What about keeping the insulation wrapped around the ducts while the mastic is setting-up?

  4. #4
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    Seal the ducts with mastic, wrap with insulation, staple the flap, then tape the seams in the insulation with UL181 listed foil tape, butyl tape(roll mastic), or film tape.
    You could use mastic on the insulation, but man what potential for mess, lol.

    The gray/black stuff that is commonly referred to as "duct tape", has no place in or on a HVAC system.
    If more government is the answer, then it's a really stupid question.

  5. #5
    Join Date
    Feb 2007
    Location
    18951
    Posts
    1,593
    This is a PITA job even with fiberglass. It's bad enough getting FG to stay and cutting correctly for elbows and Ts. I've seen jobs where people tied ropes around the insulation because it started to fall off after a couple of years.

    Now you're compounding the difficulty by wanting to use 2" cotton. I've never used it, but my guess is that it's pretty heavy, and will retain moisture a lot more, causing your metal ducts to rust out, and creating a great place for mold to grow.

    If you already bought this stuff, then install it yourself, and you'll find out just how easy/hard it is. If you find a tech willing to install it, pay him by the hour and don't ask for a guarantee. If you want a guarantee, ask the manufacturer for a list of recommended installers.

    If you don't already have the insulation, then spray foam the ducts. Although expensive, if it's in an area rarely seen, you're much better off.

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