How to prevent cold air from dropping down the bath fan duct

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In my new home, on the second floor, the bathroom fans goes outside and under the roof, so the output is upside down.

They installed the type of vent with a flap that, normally with gravity and perpendicular to the ground, stays shut but since they are installed upside down they stay open all the time.

I thought about a vent like we have in the kitchen's fan, a valve that opens only when air is pushed one way, but not sure if there are any off-the-shelf for bathroom fans.

We hit -20C the past few days and the cold air was pretty apparent.

Anything I can do here?

Best Answer

I am going to answer this even though i should probably wait for more information.

Bathroom, and dryer vent, outlet caps that exit a wall are generally attached to the exterior wall with screws, one at each corner. There may be some silicone caulking as well. They have a male crimped pipe that fits into the duct coming from the source.

You should be able to remove the screws and pull it directly out, turn 180 degrees and re-attach.

Here is YouTube video of one with a spring loaded flapper.

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3" or 4" Round Duct Black Wall Cap w/ Damper, supplyhouse.com