Water from Bathroom Exhaust fan


Old 03-02-05, 12:53 PM
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Water from Bathroom Exhaust fan

I recently installed a new quieter, more powerful bathroom fan. The old fan was exhausted to the soffit at the end of the tresses. I noticed in that area some black mold starting to form and decided to vent the new fan to the air vent in the roof. The old fan was vented with plastic hose and I used flexible metal tubing to vent the new fan.

Now, when running the fan during a shower in the morning, I am getting water drips from the ceiling around the fan. I am guessing this is condensation from the hot bathroom air and the cold attic air and possibly the colder air from around the roof vent.

How do I stop the water from collecting and dripping from the fan?? Was the decision to vent to the roof a better option than venting into the soffit??
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Old 03-02-05, 01:21 PM
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You may have to insulate the duct pipe. Being metal and passing through a colder area is probably the cause of the problem as you have stated. Good luck.
Old 03-02-05, 03:52 PM
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Yep, I agree with majak again.
Wrap 6" insulation batts around the pipe and hold them in place with duct tape (but not too tight). That should stop the condensation problem.
Good luck!
Old 03-02-05, 05:31 PM
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From the sound of things you have the vent pipe going pretty much up right as it leaves the fan. Don't sound like the best idea I ever heard. Insulating it is not going to keep it warm enough to stop condensation imho. I say use the soffit.
Old 03-03-05, 04:50 PM
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If you would look at what I provided here, you should be able to rectify your problem once and for all! I think this will help....



http://www.lowes.com/lkn?action=howT...c=howToLibrary (it shows soffit vent option)

1. Exhaust airflow must take the air all the way to the outside of the building - This is Code. (not into the attic area even if it is directly under any roof venting or just to the space of the soffit).
2. Duct runs should be short and as straight as possible.
3. Use smooth, rigid ducting whenever possible.
4. Slope ducting to the outside to allow any condensation to weep to the
outside of the building.
5. Ducting running through unheated spaces must be insulated.
6. Exhaust hoods must prevent birds or animals from entering.

Hope this helps!
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