How often do air-admittance valves go bad?

I recently moved into a newer (1997) house which has at least six or seven air-admittance valves. There's one under the sink in the kitchen, one in the (main level) laundry room, one under the sink in the master bath, etc.

I noticed that every once in a while there are some odd smells...not so much sewer gas, but more sewage-like. I was gonna blame it on the dog, but he was not nearby.....

Do these AAVs go bad, stick, or need cleaning?

Are random smells with AAVs normal? Any better models with a charcoal filter or something? Put a sock on it?

Is there some other issue to be concerned about, such as some other blockage or flow problem to watch out for?

The house has four el-cheapo builder-grade toilets that block up very frequently, but I'm sure that's purely a function of the cheap toilets and what the young-uns put into them.

some aav's are better than others. The mechanical ones with a spring for 5 bucks are cheap. Studor vent makes better ones. Venting throught the roof is obviously the best option. They can go bad. They should only open up on negative pressure. Otherwise, they should remain closed so you shouldn't get any sewer smell.



Oatey 39017 SURE-VENT AIR ADM VALVE, 1-1/2-Inch by 2-Inch, White

I see that I can buy Studor AAVs at one of the big-box stores. As long as mine are threaded on, I'm gonna swap them out to be safe. $22 each.

Thanks for the reply.



Photo added by Terry Love

did I read that right, you have at least 7 AAV's in your house? Is your hose on or did it come with wheels?

As long as you have 1 stack though the roof you will be fine. Have install 100's of Studor vents in the past 10 years and only had 4 that were defective.

The failure rate does not seem to be too high, but you still must leave it (them) with easy access just in case. Many pro plumber absolutely oppose them, others will use them where a connection to an outside vent would be very difficult and/or expensive. Some local code prohibit them, so you need to be sure you can legally use them where you are. If you use them where there are not legal, if you ever sell your home, you will be required to install legal vents to the outside before a loan will be approved.

Gary Swart said:

The failure rate does not seem to be too high, but you still must leave it (them) with easy access just in case. Many pro plumber absolutely oppose them, others will use them where a connection to an outside vent would be very difficult and/or expensive. Some local code prohibit them, so you need to be sure you can legally use them where you are. If you use them where there are not legal, if you ever sell your home, you will be required to install legal vents to the outside before a loan will be approved.

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After reading 7 aav's I had to get out the trusty old duc-tape helmet and sit down for a spell.

that is excessive

that is pretty excessive....7

I suppose it will work ok, but the reason the
units are going bad is probably because they are being
overworked......

my guess is you probably dont even have a real vent out the roof....

We have done homes with more than that here in Florida, This place has its own rules. Builders down here want limited holes in their roofs, especially the tin ones. We have a commercial project going on that has 1 3" VTR and 44 Studors. One thing with the AAR's you must have at least 1 vent thru the roof. Like I said earlier they do work well, been installing them for the last 11 years.

It appears that most of you folks are from up north and to the west so codes are totally different. I remember doing the plumbing installation at a Motel 6 in Dayton Ohio back in the winter of '85, never saw so many vent stacks in my life.

I will never like AAV's and never will. I am happy to say I am in a state that does not allow them in any shape or form.

nhmaster said:

did I read that right, you have at least 7 AAV's in your house? Is your hose on or did it come with wheels?

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I used to associate AAV's with Tin hoses on wheels...
Funny thing though...
More and more new tin houses on wheels are coming with through the roof vents & more and more multi million dollar homes built by penny pinching GC's and lazy plumbers have AAV's...

I guess the people living in trailers got tired of smelling poop gas & hearing funny noises...

Go figure!

C NUMB said:

We have done homes with more than that here in Florida, This place has its own rules. Builders down here want limited holes in their roofs, especially the tin ones. We have a commercial project going on that has 1 3" VTR and 44 Studors. One thing with the AAR's you must have at least 1 vent thru the roof. Like I said earlier they do work well, been installing them for the last 11 years.

It appears that most of you folks are from up north and to the west so codes are totally different. I remember doing the plumbing installation at a Motel 6 in Dayton Ohio back in the winter of '85, never saw so many vent stacks in my life.

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Yes, we consider Fla. to have a very lax code.