Our bathroom has a ceiling fan/light combination that lets in one hell of a
draft. During our saga about the leaking bathroom roof (resolved, it
seems, finally), I got a look at the construction, and the exhaust fan
shunts the air through something that looks a bit like a dryer hose, to a
circular exterior port on the house. That port is hooded, and there is some
kind of apparently useless circular "flap" that does very little to keep
cold (!!! it was 20 below last night) air out of the bathroom.
If you wizards can suggest a way to solve this, other than only showering in
the summer, I would be eternally grateful.
If the wind is blowing on that damper, some is gonna get through, especially
if it's a short run of duct. One thing you may want to check though, there
should be another damper right inside the outlet flange of the fan itself.
If it's missing, certainly more air will get through, than should
I recently bought a couple of mid range type bath fans made by 2
different major manufacturers. I was very surprised to see how
poorly designed the swinging damper was. In both of them, it was
very easy for the damper to get hung up by just shifting maybe 1/16 of
an inch to the side, at which point it would hit the side and bind.
If you're ever installing one of these, make sure the damper is
working correctly before you install it and again before you close up
the ceiling. It's also possible in the above case that someone had a
problem with the damper in this fan not opening correctly and removed
it, which would be real tempting if you could get it out without
tearing the ceiling apart.
If its that cold, I would duct tape the fan off until it gets warmer.
On my new fan the damper could be installed reverse so it lets outside air
in but won't allow exhaust. See if that's not your case.
When it's that cold, the relative humidity is so low that moisture inside is
going to dissipate rapidly without the help of an exhaust fan. Tape it off
during the coldest weather.
Also, in your attic area, if you have room, you could make a trap with the
exhaust flexduct. Try to route it as high as possible between the outlet
wall fitting and the fan unit. Cold air falls, and the rise area will
reduce the velocity.
Generally, heat rises so cold air coming in from the top of your
bathroom suggests that a negative pressure exists in your house. So
check the fans internal flapper, and find out what is causing your
house to have a verse stack effect in the winter.
tom @ www.BlankHelp.com
It is possible with some units to put the plastic exhaust piece on
In that case the flap stays open.
If you get at it it is easy to take it off and turn it around.
If you can't just lower the motor and plug the hole.
IMO bath fans are over rated anyway.
I never turn mine on.
You might try caulking around the fan where it meets the ceiling. How about
getting some aluminum duct tape and taping over the holes inside the fan
housing? I bet the fan and motor comes out. Tape any seam.
You might try adding an inline damper such as that offered for clothes
dryer. Make sure the fan have enough CFM's to open all dampers.
Regardless of what you do, when it is windy the dampers will open and you
will lose heat. It is a matter of low pressure outside and higher pressure
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