# AAV question



## e hilton (Nov 23, 2021)

SFR in California, full kitchen remodel.  The kitchen sink used to have a wall behind it that contained the vent line.  New plan call for the sink to be on a peninsula, same location, so the drain doesn’t change but the vent goes away.  Plumber proposes to install an AAV under the counter.  

2019 CPC 909.1 calls for the vent line to loop up as high as possible, not less than drainboard height.  That implies that a backsplash is needed to get the pipes high enough.  Or would you allow the pipe to be below the counter?


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## Joe.B (Nov 23, 2021)

CA plumbing code does not allow AAV's. Some of my neighboring jurisdictions will allow them in certain circumstances, but I have not. Every Island vent I've seen included a backsplash to accommodate for being above the flood line of the sink.


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## bill1952 (Nov 23, 2021)

So you wouldn't allow this? Can you explain the hazard to me?


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## Joe.B (Nov 23, 2021)

Yes I believe I would approve that in a situation that didn't have a backsplash built in. I don't see a hazard. It just happens that I've only seen 3-4 of these installed and they all had the backsplash so the were able to go above the flood level. I think it comes down to interpretation of "not less than the drainboard height" so given the situations I've seen _as high as possible_ was definitely above the _drainboard height. _To the best of my understanding the graphic you have shown would meet the intent of the code assuming that elbow was as "high as possible." 

909.1 General

Traps for island sinks and similar equipment shall be roughed in above the floor and shall be permitted to be vented by extending the vent as *high as possible*, but *not less than the drainboard height *and then returning it downward and connecting it to the horizontal sink drain immediately downstream from the vertical fixture drain. The return vent shall be connected to the horizontal drain through a wye-branch fitting and shall, in addition, be provided with a foot vent taken off the vertical fixture vent by means of a wye branch immediately below the floor and extending to the nearest partition and then through the roof to the open air, or shall be permitted to be connected to other vents at a point not less than 6 inches (152 mm) above the flood-level rim of the fixtures served. Drainage fittings shall be used on the vent below the floor level, and a slope of not less than 1/4 inch per foot (20.8 mm/m) back to the drain shall be maintained. The return bend used under the drainboard shall be a one-piece fitting or an assembly of a 45 degree (0.79 rad), a 90 degree (1.57 rad), and a 45 degree (0.79 rad) elbow in the order named. Pipe sizing shall be as elsewhere required in this code. The island sink drain, upstream of the returned vent, shall serve no other fixtures. An accessible cleanout shall be installed in the vertical portion of the foot vent.


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## e hilton (Nov 23, 2021)

Joe … problem is ... in the text you pasted it says in bold “not less than drainboard height”.   So even though the graphic shows the top of the loop under the counter, the text says that’s not acceptable.


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## bill1952 (Nov 24, 2021)

e hilton said:


> Joe … problem is ... in the text you pasted it says in bold “not less than drainboard height”.   So even though the graphic shows the top of the loop under the counter, the text says that’s not acceptable.


Where's the hazard?  What can go  awry that wouldn't if the elbow was an inch or so higher?


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## e hilton (Nov 24, 2021)

bill1952 said:


> Where's the hazard?  What can go  awry that wouldn't if the elbow was an inch or so higher?


That’s not for me to say.  Speaking as a code official (which i am not) ... I don’t make the rules, i enforce them.


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## Beniah Naylor (Nov 24, 2021)

I don't believe that is a requirement in the I- series plumbing codes...

P3114.4 Location.
Individual and branch air admittance valves shall be located not less than 4 inches (102 mm) above the horizontal branch drain or fixture drain being vented. Stack-type air admittance valves shall be located not less than 6 inches (152 mm) above the flood level rim of the highest fixture being vented. The air admittance valve shall be located within the maximum developed length permitted for the vent. The air admittance valve shall be installed not less than 6 inches (152 mm) above insulation materials where installed in attics.

I lived in a house that had an air admittance valve installed at the kitchen sink, and at some point the AAV was removed and the sink was re-plumbed with no vent at all. The sink gurgled when it drained... but there was no hazard that I ever encountered.


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## Pcinspector1 (Nov 24, 2021)

Loop design works and would be approved here. Very seldom do I see that set-up i get the lazy way with an AAV most of the time. Have to tell the plumber to raise the AAV 90% of the time.


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## bill1952 (Nov 24, 2021)

Pcinspector1 said:


> Loop design works and would be approved here. Very seldom do I see that set-up i get the lazy way with an AAV most of the time. Have to tell the plumber to raise the AAV 90% of the time.


Is the diagram I posted called a "loop design"?


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## Joe.B (Nov 24, 2021)

e hilton said:


> Joe … problem is ... in the text you pasted it says in bold “not less than drainboard height”.   So even though the graphic shows the top of the loop under the counter, the text says that’s not acceptable.


I agree, and that's why I posted the whole text. I agree with your assessment that the graphic does not meet the literal definition of the text, but in a situation where someone asks me specifically to make the call on an island assembly with no backsplash I would probably approve it based on the intent of the code and making the loop "as high as possible." So far I haven't had to make that call yet.


Beniah Naylor said:


> I don't believe that is a requirement in the I- series plumbing codes...
> 
> P3114.4 Location.
> Individual and branch air admittance valves shall be located not less than 4 inches (102 mm) above the horizontal branch drain or fixture drain being vented. Stack-type air admittance valves shall be located not less than 6 inches (152 mm) above the flood level rim of the highest fixture being vented. The air admittance valve shall be located within the maximum developed length permitted for the vent. The air admittance valve shall be installed not less than 6 inches (152 mm) above insulation materials where installed in attics.
> ...


CA plumbing code is based off of the Uniform Plumbing Code which is far more restrictive than IPC.


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## Beniah Naylor (Nov 24, 2021)

Is there an appreciable improvement of quality or function when a plumbing system is designed to meet the Uniform code instead of the International code?
I have never really been involved with plumbing that was done to the Uniform code.

All or most of the plumbing code experts you can find online are UPC guys, which kinda makes it hard to really study the IPC - you never know if what they are teaching you is relevant in the IPC world.


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## Joe.B (Nov 24, 2021)

Beniah Naylor said:


> Is there an appreciable improvement of quality or function when a plumbing system is designed to meet the Uniform code instead of the International code?
> I have never really been involved with plumbing that was done to the Uniform code.
> 
> All or most of the plumbing code experts you can find online are UPC guys, which kinda makes it hard to really study the IPC - you never know if what they are teaching you is relevant in the IPC world.


I've never worked under the IPC, so I'm in the same boat. I think there are aspects of the UPC that make for a more fail-safe system. AAV's are a perfect example because they are a mechanical device that can fail. Following UPC means creating a system that does not rely on any mechanical parts that could fail. UPC doesn't allow as much wet-venting, and generally a UPC design will end up with a larger proportion of venting to fixtures. They are more strict in every way which makes the install more expensive. There was an article that ICC put out boasting how much money IPC could save builders over the UPC. Another example of a difference between the two is UPC (or at least the CA version) does not allow plastic DWV piping for more than two stories of a building. Skeptics of this claim it's only there to support the cast-iron pipe manufactures, but my research indicated that this was because buildings settle over time and the plastic pipes don't handle that as well as cast iron.


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## mtlogcabin (Nov 24, 2021)

Joe.B said:


> The* return bend used under the drainboard *shall be a one-piece fitting or an assembly of a 45 degree (0.79 rad), a 90 degree (1.57 rad), and a 45 degree (0.79 rad) elbow in the order named.


The diagram posted above is code compliant under the UPC or IPC. Read the remainder of the code section and it states the return bend being under the drainboard.


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