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  1. #1

    Return Duct Sealing

    My first floor air/heating equipment is in a crawl space and being somewhat physically handicapped I can't get in there any longer. I discovered that the return duct register box and duct have become separated as shown in this photo. Is it ok to I seal this from the inside with mastic and aluminum tape or does it have to be resealed around the outer rim of this box? I am getting ready to sell the house so I don't want this to be an issue with the home inspector.

    Thank you
    Name:  Screen Shot 2013-05-19 at 11.27.33 AM.jpg
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    Taken looking downwards, although not shown, there are a couple of small holes in the black material to the left

  2. #2
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,189
    I'd clean the metal & inner liner of flex & use
    hardcast brand 1402 mastic tape.
    unlike foil tape it will stick to both surfaces
    for a long long time.
    paint on mastic would do the same thing...
    but you need to have the inner liner held
    in place long enough for mastic to dry.

    ideally from in the crawlspace the inner liner
    would be held in place by lock tie (pundit tie)
    mastic from inner liner onto duct collar.
    then once this dries (if you use paint on &
    not hardcast 1402 mastic tape)
    the insulation jacket would be brought in
    contact with return box..another lock tie
    and mastic seal of ins jacket to return box.

    the former would be easier, the latter is the
    proper way to do this repair.
    small holes can be either product mastic tape
    or paint on mastic.

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

  3. #3
    Quote Originally Posted by energy_rater_La View Post
    I'd clean the metal & inner liner of flex & use
    hardcast brand 1402 mastic tape.
    unlike foil tape it will stick to both surfaces
    for a long long time.
    paint on mastic would do the same thing...
    but you need to have the inner liner held
    in place long enough for mastic to dry.

    ideally from in the crawlspace the inner liner
    would be held in place by lock tie (pundit tie)
    mastic from inner liner onto duct collar.
    then once this dries (if you use paint on &
    not hardcast 1402 mastic tape)
    the insulation jacket would be brought in
    contact with return box..another lock tie
    and mastic seal of ins jacket to return box.

    the former would be easier, the latter is the
    proper way to do this repair.
    small holes can be either product mastic tape
    or paint on mastic.

    best of luck.
    Thank you so much for replying to me. I'll probably ask an HVAC engineer to have a look and if it's not exorbitant, have them do it from below, if not I'll go with your solution.

  4. #4
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,189
    good deal. glad to have been of help.

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

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