Bathroom exhaust exterior wall vents

davekirkendall

What are some options for exterior wall vents? I just finished a home and there is a couple bathroom exhaust vents with flappers on the north side of the home that is allowing cold air to penetrate the duct work. Is there some better designs available to prevent this??

mrgins

Is there no way to go thru the ceiling and then the gable?

1910NE

there are one way baffle/flapper things available that are connected in line. the force of the fan will push the flapper open, but wind from the outside will actually hold the flapper closed. they are not perfect, but better than nothing.

JulesB

I'm in a similiar situation. I'm in need of a quality wall mount bathroom fan, but am worried about blowback. Research thus far, hasn't produced any info specific to solving air infiltration issues. Any further advice out there for davekirkendall and myself??

Thanks,
Jules

In my case, I can't reach the attic and a gable to exit.

mrgins

Davek, have you tried tamarack technologies?
Jules, can you go thru the soffit?

JulesB

Mrgins - It's tight, but doable. 5" clearance at the outer edge of the top plate under a 3.75/12 roof pitch. Soffit is 12" deep, and drops below the top cap approx. 6". I'm pretty sure I can get a 4" pipe to make the corner.
Actually, I'd prefer to run it this way, but have ran across negative input, including at this site, regarding soffit exits. Mold issues, downhill flow, etc. What are your thoughts?

Dave - not trying to steal your thread. Quite coincedently, I ran across your post while getting ready to make an almost identical post. Figured we could do it in one shot. My apologies.

mrgins

I've done it where I've had no better options. It's not as if it's a 24/7 stream of hot air being drawn back thru the soffit into the attic. It also assumes that the attic itself is well vented.

JulesB

That's where one of the rubs is. I'm setting the air handler in the attic, so I'm insulating the underside of the roof (sprayed foam) to create a conditioned space. No soffit vents. I'm uncomfortable with the idea, but there's a lot of evidence to suggest it works well.
It's my understanding sealing up a house tight requires a whole house air exchanger. I'm currently researching if this can be incorporated into/with the bath fans, as I'm going to have 4.
So much to learn, so little time.....

mrgins

But you DO have an overhang,yes?

JulesB

Yes, 12 inches......
I'll try to get some pics uploaded later tonight.

mrgins

OK so it's a moot point about exhaust air being drawn back into the attic.

JulesB

Yes, evidently, I wasn't following you at first. My concern is pushing condensation/humidity out a short-run 4" vent stack that takes a 6" downturn and dumps under a 14 1/2" overhang/eave. Thoughts?....

mrgins

I don't see a problem with that. The only problem I see with soffit exhaust is that it can be drawn back in to the attic, but in your case it can't. Let's wait for some other opinions.

JulesB

Thanks, Mrgins.

I should of started my own thread. Didn't see it heading in a different direction than DaveK's. Once again, my apologies for thread stealing....

oregondiy

Just my personal experience in my house. I have a bath vent that vents out the eave of the house and I get mildew issues on the underside of the roof decking there where ther exhaust exits. I am planning on changing this soon to a roof vent.