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We’re having a ventless dryer delivered next weekend. How should we seal the old vent?

calum_wilde | Posted in Mechanicals on

The laundry room is finished; I’m not looking forward to the idea of cutting out the drywall to be able to remove the screws so I can pull the vent hood out from the outside. Any suggestions? Or should I just do the drywall work? Should I leave the duct alone and seal at the indoor end in case there’s ever reason to go back to a vented dryer?

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  1. Ensoulation Delux | | #1

    Not a bad first move, make sure you aren't having issues with the new system, the only place the water can go from out of the clothes is into the room...
    Quick drywall repair tip, cut the scrap you intend to replace the hole with, trace the around the scrap where the cut will be, cut opening, throw in a chunk of ply high and low and screw so they are sticking up in the opening as a backstop. It can be a bit easier to cut the hole to the replacement than the replacement to the hole! This also would work with some exterior sidings.

  2. Ensoulation Delux | | #2

    Doubled down there.

  3. GBA Editor
    Martin Holladay | | #3

    Only you can decide whether you want to permanently remove the vent termination, or whether to keep it for possible future use. I would probably keep it -- a future homeowner may appreciate it.

    From the interior, you can pack the inside of the duct with fiberglass or mineral wool insulation, and then you can install an airtight interior seal (either a gasketed piece of attractive wood -- basically, a small panel -- with 4 screws, or taped drywall).

  4. calum_wilde | | #4

    Thanks guys!

  5. user-5946022 | | #5

    Reviving this old thread. Was just able to score a heat pump dryer.

    I cannot totally remove the vent as I think it will be required when the house is sold (or perhaps much sooner if this heat pump dryer does not gain household approval). So my goal is to air seal and insulate the approx. 1' of venting I have from the dryer to the exterior in a manner that is easy to install, and easy to remove.

    I'm considering air sealing from the exterior by placing a magnetic cover over under the exterior flapper, and insulating and further air sealing from the interior by placing a plastic shopping bag into the vent from the interior and filling it with minimally expanding spray foam so it forms to the size of the duct. The idea is that both are easy to remove.

    A thin membrane would fit between the exterior flap and vent body as the exterior vent is this type:

    Sealing from the interior would be difficult due to the termination type, but insulating is possible. The interior termination is this type for a 2x4 wall, installed on an exterior 2x6 wall with some insulation behind it:

    The vent goes up about 6" from the box, turns a wide 90 and goes out through a brick wall.

    Is the above method acceptable? Anyone have better ideas?

  6. jadziedzic | | #6

    Is the open end of the section of duct inside the DryerBox round or oval shaped? (If you have the 2x4 wall model it is probably oval shaped, although maybe it goes back to round at the open end.) If the duct is round pick up a 4" duct cap at your local home center along with some metal duct tape (NOT the fabric tape commonly known as "Duck Tape"). Stuff insulation into the duct from the inside, insert the cap, and tape around the perimeter with the metal tape. Here's a link to a duct cap from Lowes:

    I'm planning that approach for a dryer vent in the house we're hoping to build, although we'll use the DryerBox model for 2x6 walls as I'll specify a 2x6 "wet wall" behind the washer & dryer.

  7. PBP1 | | #7

    I had new construction with two washer/dryer stations, one up and one down. I told everyone I was going to use a ventless heat pump dryer for the down station and wait on up.

    Some said code required a vent, so vents were installed. I plugged both.

    I would plug the vent (both ends) and keep it. You never know when you might want to run some CAT cable or something else from indoor to outdoor.

  8. user-5946022 | | #8

    @PBP1: LOL - I won't be running Cable through the dryer vent! Yes, you are correct, code absolutely requires a vent and that is enforced here.

    @Joseph: Good idea, but you are correct - it is oval, so I don't think the duct cap will fit on the inside. I also don't think I can make it fit on the outside because there is so little space on the outside, but it might be worth a try.

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