Bathroom Fan, Very Loud, Still Foggy

[DKAudio]

I just installed a bathroom fan. Our bathroom never had one before. I cut through the sheetrock ceiling and used 4" duct and vented through the roof. I then insulated the duct VERY well in order to avoid condensation. The unit is either a BF125EM or a BF145EM made by GE. I used the fan three times now durring a shower and everytime the mirrors, window, anything chorme is foggy. The walls are damp as well, just like before when I didn't even have a fan. I put a piece of tissue up to the unit and it sucked it and held it in place. I don't understand why it is not working properly. The unit I got is for bathrooms up to 120sq ft, mine is only around 50. It is also extremely loud, I think it was 4.5 sones. I wasen't expecting it to be this loud though. The box said medium sound level so I was expecting an average sound. The unit was $80 so I am very dissapointed. I already threw out the box and sheetrocked, mudded and painted so I cannot get back up to it easily. Any suggestions? Thanks

After thinking about it do you think the fan is too powerful for my small bathroom and it creates a vaccuum because not enough air can get in as it takes out? Can I just get a weaker, quieter motor and use the same housing, ducting? It is a squirrel cage type motor.

[kactuskid]

Is there a built in damper on the roof vent that you installed, it's possible that it's not opening when the fans exhaust is blowing, perhaps it's hung up.

Also make sure you have an airgap below the bathroom door to allow makeup air to get through to compensate for the exhaust blowing out.

You can usually replace the fan moter with another one of the same size and use the existing housing. Just drop down the fan moter by prying it back on one side. Undo the wiring connections and then measure the inside of the housing to know the replacement size. But, the existing fan size should work ok as long as you have makeup air and the duct dampers are open.

Some of the cheaper fan units are pretty noisey, the lower the sones the less noisey they are.

[DKAudio]

yes, it has a damper. I was actually going to check that today when I get home. I tried leaving the bathroom door cracked last night and it still fogged up. I will check the dampers, there is one on the fan unit itself too.

[DKAudio]

Ok, I got up on the roof, the damper was up but only about 1/2". I went back down and noticed that one side of the squirrel cage was sucking and I was getting a lot of blowing around the opposite side. Any ideas?

[DKAudio]

I figured it out, I screwed the 90* aluminum duct to the fan outlet so it wouldn't move. My screws were blocking the built in damper on the fan. I took out the damper (just a cheap plastic swing type) and the fan now only sucks, it is quieter too (about an average bathroom fan volume). So my question now is do I need to have a damper on the fan side? What would be the cons of not having one? Will a lot of my house heat escape from there in the winter? Thanks

[kactuskid]

The only con I know of is yes, you'll lose heat, but, if the damper on the roof vent is closed when not in use, and since the ducting is insulated, your losses should be minimal. I'd just leave it as is for now and see how it goes. Don't throw away the small plastic damper you removed just in case you wanna ever reinstall it.

[JCA1]

the damper on the fan stops outside air from coming into the house when the fan is not in use.

[siukin]

I was thinking also to add a fan to my bathroom but reading this thread it just seems to problematic :P

[DKAudio]

Lol, old thread.

It was easy, the biggest thing you need to worry about is cutting a hole in your roof. Just lay your shingles on top of the backside...I have never had any issues since the fan was completed a year and a half ago.