Bathroom fan lets in draft.


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.
Donna
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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

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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.
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There should be a flap both at the fan and the hood, and together they work OK. But here is an inline vent blocker you can add:
http://www.batticdoor.com/bathfandraftblocker.html
--
Dennis


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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.
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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.

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On Sat, 27 Jan 2007 14:00:08 GMT, "Donna"

imho:
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
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It is possible with some units to put the plastic exhaust piece on upside down.
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.
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Donna wrote:

Got a spare towel to stuff int he hole?
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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 inside.

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