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-   -   Advice on bath exhaust vent termination. (https://www.nachi.org/forum/f18/advice-bath-exhaust-vent-termination-66602/)

dmacy 12/1/11 5:43 PM

Advice on bath exhaust vent termination.
 
I wanted to ask your opinion on the duct termination for my 2 bath exhaust fans.

The question I have is for the termination of one of the fans. It would be easier for me to cut through my cedar siding to do a side wall termination. It would be about 12 -15 feet total vent length. If I did the roof I would need to hire someone to vent through the roof(About 3 feet)

The fan is a Broan Model 683 CFM 80 http://www.broan.com/ImageLibrary/br...s/99043984.pdf

Not sure of the maximum length of vent.

For sidewall application.
Would you slope vent up slightly or run on attic floor?
What type duct would you use? Flex, semi corrigated metal?

Thanks!!

jmckee 12/1/11 6:50 PM

Re: Advice on bath exhaust vent termination.
 
Dave....side wall vent should be fine with that fan and why cut another hole in the roof...15 feet should be no problem with which ever material You choose to work with
just make sure You have a check valve in there for back flow wind and I would say across the floor is fine...

lkage 12/1/11 6:51 PM

Re: Advice on bath exhaust vent termination.
 
Quote:

Originally Posted by dmacy (Post 846771)
I wanted to ask your opinion on the duct termination for my 2 bath exhaust fans.

The question I have is for the termination of one of the fans. It would be easier for me to cut through my cedar siding to do a side wall termination. It would be about 12 -15 feet total vent length. If I did the roof I would need to hire someone to vent through the roof(About 3 feet)

The fan is a Broan Model 683 CFM 80 http://www.broan.com/ImageLibrary/br...s/99043984.pdf

Not sure of the maximum length of vent.

For sidewall application.
Would you slope vent up slightly or run on attic floor?
What type duct would you use? Flex, semi corrigated metal?

Thanks!!

Also, running them out a sidewall with rigid duct buried in insulation to prevent condensation is good.

The distance run would depend on the size of the bathroom and cfm of fan but, like Jim said, it should be okay.

growden 12/1/11 6:58 PM

Re: Advice on bath exhaust vent termination.
 
Hi David
I would suggest the easiest install
12-15 feet is not too long and I would also use a flex itís easier to maneuver around. I would also recommend arching the flex piping to prevent water intrusion at termination.

ccurrins 12/1/11 7:22 PM

Re: Advice on bath exhaust vent termination.
 
Personally I prefer sidewall termination.

dmacy 12/1/11 9:06 PM

Re: Advice on bath exhaust vent termination.
 
Thanks, I appreciate the feedback.

rernst1 12/1/11 10:14 PM

Re: Advice on bath exhaust vent termination.
 
I like either way but if the sidewall is what you can do that's what you should do. I like the idea of it being insulated and the sidewall is the easier way of doing that especially if you have blown in. I also prefer the caps with the three louvers. http://www.homedepot.com/h_d1/N-5yc1...atalogId=10053

dmacy 12/2/11 3:10 PM

Re: Advice on bath exhaust vent termination.
 
5 Attachment(s)
The vent installation went very well today and thanks to you guys I saved a few hundred dollars.

A roofer wanted a minimum of $350. It cost me around $100.

I attached a few pics of the install. I just want to insulate the exposed pipes in the attic and patch my siding as I had to close to a window.

The hole saw combo worked great and seems to be of good quality.

I am going to post the inferior fan set up that was there before, leaking at connections and molding the wallboard. (I am ashamed to admit I was the dolt that installed the 1st fan about 7 years ago.

Thanks again!!

jfunderburk 12/2/11 3:26 PM

Re: Advice on bath exhaust vent termination.
 
I would vent it into the attic (I know you aren't supposed to) before I would put it out the roof. That would be a leak waiting to happen!

ccurrins 12/2/11 3:33 PM

Re: Advice on bath exhaust vent termination.
 
Quote:

Originally Posted by jfunderburk (Post 847124)
I would vent it into the attic (I know you aren't supposed to) before I would put it out the roof. That would be a leak waiting to happen!

Not if properly flashed like any other roof penetration, (sewer vent, furnace pipe, etc.).

jfunderburk 12/2/11 3:37 PM

Re: Advice on bath exhaust vent termination.
 
Quote:

Originally Posted by ccurrins (Post 847128)
Not if properly flashed like any other roof penetration, (sewer vent, furnace pipe, etc.).

So properly flashed penetrations never leak? What is the life span of the flashing or the metal or plastic vent?

growden 12/2/11 6:11 PM

Re: Advice on bath exhaust vent termination.
 
Quote:

Originally Posted by jfunderburk (Post 847130)
What is the life span of the flashing or the metal or plastic vent?

Joe
Thatís a good question; you would think that metal for the most part would out last the plastic vent cover by far and a few years ago that may have been true, but with the improvements they have made with plastic materials itís hard to truly say.
I would suspect the life expectancy of the plastic vent cover would be determined on the extreme weather conditions it had to endure, quality of the plastic used and location.

And David
I personally would still arch the last few feet of the flex vent piping above the termination point (vent cover) this will help prevent any possible chance of water running back into flex piping in the event of water intrusion. Just a thought.

nhagarty 12/2/11 6:53 PM

Re: Advice on bath exhaust vent termination.
 
Gable ends, sidewalls and eaves are always the preferred method of termination. Only as a last resort do our technicians install venting thru the roof.

wwalmsley 12/15/11 10:49 PM

Re: Advice on bath exhaust vent termination.
 
Just an observation but the last few ft. of the pipe should be wrapped with insulation condensation will occur.Warm pipe cold attic air..

mgratton 12/16/11 12:06 AM

Re: Advice on bath exhaust vent termination.
 
https://www.nachi.org/bathroom-ventil...ducts-fans.htm

And the best practice is to slant horizontal runs of duct down toward the exterior outlet to drain any condensation outside, just saying!


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