One roof vent for two bathroom exhaust fans?


Old 10-10-06, 09:55 AM
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One roof vent for two bathroom exhaust fans?

I have two bathrooms upstairs (next to each other), and they will each get an exhaust fan. Of course, they wont' vent to the attic. Instead, they will vent outside, through a roof vent. Question: is it OK to use a "Y" vent duct connection-- that is, the duct of each fan connect at one point forming one duct somewhere inside the attic, and then this single duct vents outside thru a single roof vent? The ducts are small (just a few feet).

Or is it absolutely essential that each fan has its own duct venting outside and its own roof vent -- which would require installing two roof vents?

Old 10-10-06, 10:18 AM
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For sure have each fan have its own vent out a roof jack with fliper in it. Dont try it with a Y and one jack.

Old 10-10-06, 05:46 PM
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I'll agree with ed if it is not done wright but this can be done if the duct is sized wright and you have in line dampers.
Old 10-10-06, 08:26 PM
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My house is hooked up this way- the fans tend to blow significant amounts of air into the other bathroom, which sucks. Most of the air goes up and out, but some still leaks back around the flappers.

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