Bathroom exhaust is 24 feet long

Old 04-09-02, 06:20 PM
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Cool Bathroom exhaust is 24 feet long

Hooking up a Broan exhaust fan in the new bathroom. It is 24 feet to the outside wall. What should I use for the pipe? Aluminum 4"', galvanized, flex pipe, pvc? Live in Michigan so I am concerned about condensation and ice.
Old 04-10-02, 09:59 AM
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Whatever you use for exhaust vent pipe is subject to condensation UNLESS it is insulated, which you should do anywhere along it where it is passing through unheated space.
The condensation can build up and run back down the vent line and drip through your exhaust fan if you don't.
I would use PVC or flex, whichever suits you. Metal will sweat more. Definitely not galvanized for a bathroom exhaust with all of that warm, moist air.
Good luck!
Old 04-12-02, 10:51 AM
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Just an additional comment:
24' is a LONG way to go with a duct for most of those little Broan fans, especially if you have any elbows in the duct. At the very least, I would suggest transitioning up to a larger duct. On my own home, I had to run about 18', so I immediately transitioned up to 6". I then ran to the outside wall and, just before I went out the wall, I installed an in-line fan and wired it with my little Broan fan. Works like a champ.

My only concern was how the in-line fan would handle the moist air, so I wired it into a ground-faulted circuit and I run the fan a little longer than needed.


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