Vent returns to itself

I’ve never seen this before. I would expect to see an air admittance valve here. Any comments?

That’sa loop vent, often used at kitchen islands. Does not have/require an AAV.

That is not what Kenton has pictured.

Its wrong wrong wrong

this is how it is done.

Thanks Mike!

Wrong design but for a quick and easy fix - how bout just adding a 90 degree bend with an AAV on that upper horizontal pipe. Looks to be 4" above the lower wye / trap fitting and offers your ‘air behind water’.
I know we r not plumbers or offer repair suggestion - just curious if that would be a proper fix, while nursing Xmas hang over and food coma.

Not exactly. But it is an attempt. Kenton said “I’ve never seen this before”. I was just giving him an idea of the intended purpose.

Its still a rough in, you need to wait and see what the plumber will do when the fixtures are connected.

It’s roughed in, but ready to cover. Nothing will be changed inside the wall. Frankly I don’t see what the problem is…is the (2)45 elbows and (1) 90 specifically required instead of a 180? We just use an AAV here, but loops may be the only option if AAVs are not allowed. Anybody have the model code reference for this?

The problem is at the 45 Tee, see pic, any blockage here or below and there is no vent. But we still don’t know what is going on, what is the rough in for? So long as nothing is connected to it there are no issues. Why did the plumber do it? Maybe it’s just for a pressure test. Maybe, its a laundry room, pipe on left will be a stand pipe, the other a laundry sink, P trap is in the slab. More info needed.

As mentioned. It is an island fixture vent, commonly referred to as a loop vent. Use is limited to sinks and lavatories (disposer OK with sink). Notice that the piping is a size larger than the drain, which prevents siphoning. There should be two cleanouts two allow rodding of all piping (I can just see the second cleanout on the left / vertical side). The verticals must extend above the bottom of the fixture drain before they start to offset (no sink yet so can’t verify absolutely, but it’s almost definitely too low based on the inlet height - I would document height as a defect on this). The wye configuration is very common with slab implementations. IMO: They are very reliable

BTW: NM cable should not be installed under the slab. Should be UF.

Not in a slab it isn’t

Maybe this one is more realistic.

Basement depictions do not apply to slab installations. You will not have a horizontal vent tied in on the vertical, nor will you have a cleanout below the floor.

I apologize for not being in your slab territory, just disregard the post.

What does a slab have to do with it?

Go back and view post #3

Show me where everything depicted in your diagram is required to be exactly as depicted. I’ll help, it’s P3112 of the IRC.

Point out what is non-compliant by citation from the authoritative source (I already gave you one - the height at the offset).

Chuck, seriously, if you think the original posted pic is correct you don’t understand plumbing. sorry.

Without adding an AAV that setup is not vented. Period

I’m sorry, but you are confused and have applied the incorrect section.

The fixture is vented. Air is free to move through the loop. The 1-1/2 diameter waste arm cannot cause the 2 inch piping that forms the loop to siphon the trap (it is sized as a combination waste and vent pipe). There are NOT “multiple island vent fixtures” in this installation, which is the standard that you have attempted to apply.

Also, you forgot this part

The installation is OK except for the height at the offset.

BTW: Typing the word “Period” at the end of your statement really doesn’t add any special authority to your opinion and certainly does not bestow upon you the final word in the matter.

The best case you could make is that it is a wet vent.

There is no source of free air behind the draining water stream with out a dry vent to atmosphere above the structure.

You you think you have given the final word . I disagree.