AskCodeMan

Question from an e-mail.

Hey Codeman, maybe you can answer this:

I am in Illinois and have been finding air admittance valves installed in some locations.

Are air admittance valves considered to be mechanical valves?

I know the Illinois plumbing code prohibits the use of mechanical valves, as do other plumbing code, but other codes allow air admittance valves and the Illinois plumbing code does not mention air admittance valves.

Can you clarify that for me?

An Air admittance valve (AAV) is not considered a "mechanical vent" by most codes.

AAVs operate based on air pressure differences and not by any mechanical means, thus they are *NOT* considered to be "mechanical valves" as such.

There are "mechanical valves" which resemble AAVs except that they operate by a mechanical means, typically, they operate against spring pressure. Mechanical vents are allowed in manufactured housing (units which are constructed in a factory and moved to the site and set up), however, mechanical vents are not allowed to be installed in site built structures.

For example, the International Plumbing Code and the International Residential Code do not allow for the installation and use of "mechanical vents", however, those codes also specifically allow for the installation and use of air admittance valves.

I looked up the Illinois Plumbing code and that plumbing code also prohibits the installation and use of mechanical vents, however, it makes no mention of "air admittance valves", nor does that code define "mechanical vents".

I am sending a e-mail to try to ascertain a definitive answer for you and will post it here when I receive it.

Codeman

The e-mail question above arrived at the end of last week, I waited to post the question and my answer until I had received a response answering my question.

I received that response today and it is included below.

Answer: Illinois considers an AAV to be a "mechanical vent", one of the few places which do so.

Mr.. Jerry Peck/Codeman, You are correct sir there is not a definition in the current (2004) Illinois Plumbing Code book describing "mechanical vents".
However a Air Admittance Valve (AAV) is indeed a mechanical device whether relying on a spring or gravity to permit the venting operation to function there is movement within the device, it is not static. This movement is mechanical, therefore Section 890.1480 d) applies. Thanks, Frank.

Frank Shimkus
Plumbing Consultant
IDPH Environmental Health
Plumbing Program

I would like to thank Mr. Frank Shimkus of the Illinois Plumbing Program for responding and providing the definitive answer the question.

We now have a definitive answer from the Illinois Plumbing Department - AAVs are considered "mechanical vents" in Illinois, which means you should NOT be finding any AAVs in Illinois.

If you inspect in Illinois and find AAVs installed, you should be writing them up for improper venting and in needed of correction.

I disagree with their position, as do most other plumbing codes, but they are the Authority Having Jurisdiction so what they say goes for their jurisdiction.

Codeman