Bathroom exhaust fan help please!

Old 10-03-12, 09:30 AM
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Bathroom exhaust fan help please!

I have two of the pictured bathroom exhaust fans in my home built in 1988, there are no markings on the plastic case and they are about 9' square. I have a few questions about them:

1. Can anyone identify who may have made them and if the plastic case will slip off for cleaning the fan? I put a camera up there to look inside and they are pretty grimy after 24 years of use (but still work). I hate to go pulling stuff down, but there are no screws or any fasteners visible to undo to take the cover off.

2. I have been in the attic and see that the one in our half bath is vented just to the attic with flex tube connected to a truss, with the end facing downward (like an upside down J) and not outside. I figured this was no big deal since they are mainly used to pull moisture out of the air. But... upon looking at the roof and soffits, I cannot see where the one in the full bath is vented to the outside, so I have to assume they did it the same way. Our ranch house attic is well ventilated and we've never had an issue with mold or moisture in it - should I have this checked out? It's been this way for 20+ years...

3. If they are just vented to the attic, can dirt / dust / whatever be pulled back through the vent into the house somehow, or do most exhaust fans have some type of backflow prevention?

Thanks for your help - Scott
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Old 10-03-12, 10:11 AM
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Gently pull down on the trim. It is on spring loaded arms that should allow it to drop down so you can access the arms and remove it.

There should be a flapper as a backflow preventer at the duct outlet on the housing.

The mechanical code requires the exhaust to be vented outside, not into the attic.
Old 10-03-12, 11:13 AM
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The mechanical code requires the exhaust to be vented outside, not into the attic.
In addition, you want to get that moisture away from your attic insulation, to keep that as dry and effective as possible - regardless of how well ventilated your attic may be.

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