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dpeter04
exhaust fan vent options

I installed a 100cfm fan in my main bath. I really do not want to vent through the roof. However, there are two sewer vents within five feet of the fan output. These sewer vents have 3" pvc which I could easily tee into. I would then put a rain cap on the vent so it would not ingest water down the bath fan vent ducting. Is there any reason I can't do this? My other option is a sidewall exhaust which would require a 28 foot run. I have a large attic above so space is not an issue.

A. Spruce
Re: exhaust fan vent options

Never, never, NEVER connect anything into the sewer system that is not sewer related!

Sewer vents are full of toxic, flammable, and malodorous gases, which you do not want coming into the house. Your best option is to either penetrate the roof with the bathroom vent or to exit through a gable end.

keith3267
Re: exhaust fan vent options
A. Spruce wrote:

Never, never, NEVER connect anything into the sewer system that is not sewer related!

Sewer vents are full of toxic, flammable, and malodorous gases, which you do not want coming into the house. Your best option is to either penetrate the roof with the bathroom vent or to exit through a gable end.

Let me add to this excellent advice. If you tap into the sewer vent, then when the fan is not running, those sewer gasses will come into your house and not go up the vent. Many of these gasses, particularly the most toxic ones hydrogen sulfide are heavier than air and are only going up the vent pipe because of gas pressure in the sewer system. They will gladly settle in your bathroom, and they don't smell very good either.

MLB Construction
Re: exhaust fan vent options

Amen to those two answers.

it's easier to vent through the roof than through the siding.....or at least as easy... unless you have ceramic roof tiles.

dj1
Re: exhaust fan vent options

We've discussed this before. I believe that code doesn't allow doing so, no matter where you live.

Like mentioned above, it's relatively easy to install a new vent through the roof. It can be done in tile roofs as well.

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