Air Admittance Valve Installation

OK - Since there was a recent discussion of AAVs, but I am not 100% clear on proper use/installation, I want to double check…

This AAV was on a kitchen sink over a slab (an addition).

The vent stack was at the rear of the home, this kitchen is located over an old garage to the side and enters the soil line just before it exits the home to the street side. (similar to another I saw previously and referred for review since local code may not allow the use of the AAV)

Is this the proper installation? As I understand the AAV operation, it is self venting, activating with negative pressure, so it does not need to be tied into the vent stack - correct?

As you can see from the picture some plumbing work is needed anyway:D , but I would like to know for my own education about this device.

Any and all advice is welcome (I am writing the report now). I will include a mention to verify with AHJ that this device is allowed, but comments regarding the proper installtion would be helpful -thanks!

small aav.JPG

This is a proper installation. Yours looks ok going by this.

The AAV may be okay, but the S-trap is no good. . .

Yeah (not to mention the bucket!) - there is also galvanized supply lines in the basement to the old bathroom, and what I can only guess is a homeowner attempt at rigging up the sump pump. Enough for a plumber to do, but I wanted to know if I was on solid ground in not recommending venting for the AAV (especially since I KNOW a plumber will be there and have his 2 cents!:smiley: )

Blaine, that is very small on my screen - is it a file you can email to me, or post in larger or attached format? Thanks!


An AAV is a vent system, so it is its own “vent stack.” The only difference is, that it doesn’t go through the roof.

The AAV should be as high as possible, and accessible.

Without looking at the balance of the drain line system in your picture, the position of the AAV looks good. . .

Thank you, Jeff. That is what I understood, but I wanted to double check with some of the higher minds here (especially you!!)

That’s in much better shape than this one.:smiley:
Happy Inspecting


An AAV used as an individual fixture vent should be at least 4" above the fixture’s drain. An AAV used as a stack vent should be at least 6" above highest fixture’s flood rim.