Vent stack odor solutions

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fosh

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New single story custom home with three full baths and a 500gpd aerobic septic.
We get considerable sewer odors on the sheltered patio on breezy days - coming out of the roof vents - especially with drain activity such as when someone is showering.

The plumber has suggested we install 5 Mainline brand AAVs on top of the vent pipes (leaving a couple of the more remote vents open)

Can't find any information whether the Mainline AAVs are suitable for outdoor-rooftop exposure. Many others seem to be limited to indoor applications.

Moreover, are AAVs a superior solution over just adding charcoal filter caps?
 

Reach4

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You have 7 roof sewer vents-- that is a lot. Interesting.
 

hj

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quote; are AAVs a superior solution over just adding charcoal filter caps?

Absolutely not! Under some conditions they can "obstruct" the flow and prevent drainage from the fixtures.
 

fosh

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It's 6 or 7 - the floor plan is pretty spread out.

Thanks -- And we fear the nasty commode burp if the system gets pressurized - We'll decline those AAVs and opt for charcoal filters instead.

These stacks are 1-1/2" and 2" and have lead flashing that we really don't want to disturb. I am considering gluing the filters to 12" sections of PVC and slipping those over the existing flashing. Maybe a very small amount of expanding foam between to help seat and seal.
 

WorthFlorida

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If you had any pictures it would help. With a lot of stacks scattered around the roof and the wind blows, the air pressures over the pipes are different. I assume you have pitched roof and as the winds blows, it is the same as the air flowing over an aircraft wing. The vents near the top of the roof will have a higher pressure over it than ones near the bottom edge of the roof. When water flows down the drain it pulls air into the vent, therefore, it is rare to smell any odors. Probably when you have the problem air pressure over one vent is much lower than another. As air is being suck out of one vent and the higher pressure vent is providing air into the vent. With a lot of vents it is very possible that as one point when water flows or not flowing there is a direct connection from one vent to another without any traps in between.

What the fix is can be tough. To experiment that this the problem, temporarily insert a PVC pipe in the lower vent to get it higher in the air to see if it helps. Another is if all of these vents are in the same attic area, you might want to join some of them to a single vent, but you have to be careful since so much vent is needed for certain size pipes and amount of drains. You plumber should be able to determine the number of connections. The filter solution is not a fix because once the carbon as absorbed all of the contaminates, they will need to be changed out.
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fosh

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Here is a link to Pics - I count 9 vents total.
The closed aerobic septic tank vents back into the structure's drain stack. We presume that as the tank takes on water and waste, the displaced gas purges into the stacks and exits the roof - wind pressure differentials contributing too. Then the breeze offers us a sample from time to time.
Extending the vents will be our first & most cost effective experiment. The three on the back of the house are the primary suspects. If we still have issues, we'll put the charcoal filters up. Bought a couple already.

Also looking for a new plumber. No confidence in the other guy.

Awesome forum BTW!
 

WorthFlorida

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At least you have a new home and it had to pass all inspections to get the CO. My next suggestion was to find a different plumber. If you're OK on the roof, when you have the problem cap off one vent at a time with duct tape and see if and when the problem goes away. The least is if you can figure out the one(s) giving you the problem it make it easier for a plumber to come up with a solution.
 

fosh

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Good idea. No problem getting on the roof.
I found that 3" DWV sections will slip right over the 2" lead flashing and the charcoal filters slip right onto the end.
I'll dry-fit two and move them around as needed - see how it plays out before gluing.
 

Growler

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If you occasionally or constantly smell sewer gas around your home on the outside, the odor is coming from your plumbing vents. Normally the wind will carry away the funk. If conditions are right, weather/wind/humidity, land slope, will carry that stink to the ground and spoil the party. Depending on the size of your house, you'll have 1 or more plumbing vents. VentGenie Filters builds an activated carbon filter that solves this problem immediately, guaranteed. Visit VentGenieFilters.com.
 
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