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Vent help


homnspector
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Originally posted by homnspector

Should this AAV / vent be above the sink rim or at least above the bottom of the sink?

I was wondering about the elevation thing myself, just the other the day. I do know that isn't an AAV, it's a mechanical vent. AAV's don't use a spring and last much longer.

That hereby exhausts my knowledge of both AAV's and mechanical vents.

Brian G.

Sometimes a Well, Sometimes a Mud Puddle [:-graduat[:-dunce]

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Originally posted by homnspector

Brian, thanks for clarifying that, I guess I never knew what the cheapie black ones were called. The only thing I can find says it must have a 100 mm rise but says nothing about having to be higher than the fixture.

Yes, they must be above the flood rim of the sink. Also doing this will typically put them in the wall, which would then require an access cover (they can't be buried). Most jurisdictions don't allow Mechanical vents but do allow AAV's. Another factor is that it cannot be the sole venting means for the house - There has to be a main vent somewhere and these can be used on limited fixtures.

Honestly I just don't like the things, either of them. They just wreak of bad craftsmanship and a totally half assed attempt at doing something right.

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Originally posted by Kyle Kubs

Yes, they must be above the flood rim of the sink.

I don't think that is correct. For this situation, an air admittance valve (NOT a cheater vent) should be at least 4 inches above the horizontal/ fixture drain.

Only "Stack-type" air admittance valves need to be 6 inches above the flood level rim of the highest fixture being vented.

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I just received my copy of Plumbing by Rex Cauldwell I ordered last week (plumbing isn't my strongest subject). On page 151 he writes, in part: "The AAV needs to be around 4 inches above the trap weir (water line)."

Is that also okay for mechanical vents? Who knows? He says not to use those at all.

Brian G.

The AAV: POS or A-OK? [?]

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Hi,

I seem to recall that a few years ago an inspector wrote an article about these for ASHI's monthly journal The Reporter. Perhaps Kurt or one of the ASHI brethren could find that article and get permission from ASHI to post it here.

OT - OF!!!

M.

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