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air admittance valve

We amended them out of the IPC and IRC for the most part. We allow them in limited use in remodels, basement finishes, etc. Basically, if it can be vented in a conventional method then we require it be done that way.

AAV's are mechanical devices, and mechanical devices can (and do) fail. Why take the chance of it failing when a conventional vent could have been installed?
 
Last time I checked on one no one could follow the SECTION 917 in 06IPC with complete details so I turned it down. Next job same contractor and plumber and they didn't even propose using it.

Maybe they will do it right.

Been on my manufactured home from the factory (2001) and works great.
 
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retire09,

I'm not for them in the residential applications. I DO understand that they

have a purpose when a confined / limited application calls for them.

I am of the opinion that because they ARE mechanical devices [ and I agree

with fatboy ] and will fail, that if installed in a residential setting, that

they should also be like any other mechanical device / equipment in the

attic areas and have an approved "catwalk" to them, a light and a

receptacle installed near them. My experiences have seen most of

the AAV's installed in a hidden area of the attic, sometimes covered over

by the thermal insulation and WHEN they fail, the homeowner doesn't

have a clue about why their plumbing fixture "isn't working like it used

to." Heck, the plumber that's called in to fix a problem [ may ] not

even know of the AAV or worse, may know about it, replace it and then

charge the unsuspecting homeowner an enormous "unneeded" fee.

QUESTION: As our famous Uncle Bob [ on this forum ] might say,

" ...what did people do before these things were created?" Designed

the vent systems correctly, to work within the design of the structure

and NOT because of some whims of a builder / designer.

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That's exactly what I told a plumber once when I rejected his AAV..........he asked "well how am I supposed to do it without the AAV?"

I replied........... just like you would have ten years ago......... ;)
 
AAV have their place in the construction world! In the dumpster!

However, there are some situations where they are a good device as an alternative to proper planning!
 
UPC does not allow them but like fatboy we have permitted them (under alternate materials) for very limited applications on remodels. Will not allow them in an attic or space that is not readily accessible. Never on new construction
 
Air admittance valves (AAVs) are pressure-activated, one-way mechanical vents, used in a plumbing system to eliminate the need for conventional pipe venting and roof penetrations plus stopping the plumbers from over boring and notching studs and joist, which we all know how much they like to do that. A discharge of wastewater causes the AAV to open, releasing the vacuum and allowing air to enter plumbing vent pipe for proper drainage. Otherwise, the valve remains closed, preventing the escape of sewer gas and maintaining the trap seal. Using AAVs can significantly reduce the amount of venting materials needed in a plumbing system, increase plumbing labor efficiency, allow greater flexibility in the layout of plumbing fixtures, and reduce long-term maintenance problems associated with conventional vent stack roofing penetrations. Standard plumbing systems use water trap seals to perform the critical function of preventing sewer gas from emanating into living areas, with fresh air pipe venting commonly used to prevent siphoning of traps. Although this method is simple and reliable, it requires each plumbing fixture to have a lateral return vent that passes through wall studs to a central stack, or to have its own vertical vent that passes through the wall, ceiling, attic, and roof. Air Admittance Valves are mechanical devices designed to maintain trap seals without the need for additional vent piping. They are one-way valves that open only under negative pressure (created when a toilet is flushed or a drain stopper is opened). When the water flow stops, gravity closes the valve, preventing the escape of sewer gasses under conditions of equal or positive pressure. AAVs are typically made from polyvinyl chloride (PVC) plastic materials with ethylene propylene diene monomer (EPDM) rubber valve diaphragms. Valves come in two sizes: one for fixture venting and a larger size for system venting. The valves fit standard diameter pipes, ranging from 1-1/4 to 4 inches. Screening protects the valves from foreign objects and vermin. ASSE (American Society of Sanitary Engineers) standards require that AAVs be tested to reliably open and close a minimum of 500,000 times, (estimated to be at least 30 years of use) with no emanation of sewer gas. Some manufacturers claim their units are tested for up to 1.5 million cycles, or at least 80 years of use. Air Admittance Valves have been effectively used in Europe for more than four decades and they have been used in mobile and manufacturer homes in the USA for the last thirty years or more. U.S. manufacturers offer warranties that range from 20 years to lifetime. AAV’s are also IAPMO approved. And I thought that Americans lead the world in construction industry so why are we taking a back seat on this issue

I have never seen a failure of an AAV but by Murphy's Law failure data, old fashioned through the roof vents fail. Nail punctures, partial and completely cut, broken al could lead to sewer gas entering building. Vent pipes covered or obstructed with debris are cause slow fixture draining. All vents are bad and they fail. A failure in my book is a product that fails due to defect in the product itself. A product that is destroyed or damaged is not a failure of the product it is a failure caused by people with tools who can't read or don't care. Examples: An illegal immigrant from Mars can't read the warning label on an AAV and blast it with texture so it can no longer be seen Marty thinks he's doing a good job. Joe six pack cuts a horizontal vent pipe in half by accident, instead of letting someone know he wraps a piece of used duct tape around the pipe after the first hot day the duct tape fails and the vent pipe separates leaking sewer gas into the house. Neither of these is a product failure.
 
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