Plumbing vent question

Plumbing is not my strong suit so this drain had me a little stumped. The house is 3 years old. This is an island kitchen sink but it doesn’t have an air admittance valve. It is 1-1/2" drain/P-trap that transitions to a 2" drain into the slab. Is it permissable to have an island drain with no air admittance valve? See photo.

i believe the horizontal leg after the trap has a minimum length requirement.

otherwise it’s considered an S-trap.

someone should chime in on the length.

in this application, i can’t see how you’de do it without an AAV.

This might help to illustrate;

Marcel :slight_smile: :slight_smile:

Marcel, that’s a neat website, I went to their homepage and looked at some of the topics under “the history of plumbing”. glad I didn’ grow up in that era!

I checked the site. However I still can’t determine if this is allowable or not. I don’t think it is, but it is such new construction I’m hesitant to call it incorrect. I was wondering if somehow switching from the 1-1/2" to the 2" drain pipe might somehow make this situation allowable.

I have to get this report out tonight so I would sure would appreciate any help.

One easy thing to remember about plumbing, pipes have to hold water and waste pipes shows that sh#t flows downhill and fumes vent uphill. ha. ha.

Marcel :slight_smile: :wink:

Section P3111.3 IRC

Marcel:) :slight_smile:

So here is what I can figure:
P3111.1 “…A combination waste and vent system shall not receive the discharge of a food waste grinder.”

Since this drain DOES receive the waste from a food waste grinder, it should not be allowed. I don’t even need to look at sizes I think. Does this sound right?

OK, I think I found the answer in P3105 and figure P3105.3. Looks like as long as it is within 6 feet of the vent (which is presumably in the closest wall) then it is OK.

I would think that the vent is probably inside the wall tieing in with other vents.

If that is supposed to be a vent, it’s on the wrong side of the trap.
It should come off the top of the 90.