Vent pipe below drain?

[Fogcity]

I’m replacing some dodgy pipes under the kitchen sink, and I’m noticing that where the drain line meets the basement wall it appears that the vent pipe is below the drain pipe. In the attached photo, the relatively horizontal 1-1/2” pipe below is the vent and the 2 inch pipe pointing upwards is the kitchen drain.

Am I wrong or do these two need to be switched?

 

[Tuttles Revenge]

Its impossible to tell from the photo what each pipes purpose is. They both appear to be drains. Vents are typically taken off of the top of a drain pipe near the fixture trap being vented.

However.. over the course of decades.. or centuries, homes get remodeled and people do weird stuff.. So its entirely possible someone connected a pipe to the drain that was intended to serve as a vent, but that isn't how or the purpose of a vent.

 

[Sponsor]

 

[Fogcity]

Thanks for the reply. I assume you mean it’s impossible to tell “what each pipes purpose” WAS originally?

Because I can confirm that the lower 1.5” pipe is routed out and up the side of the building, and that the upper 2” pipe is routed from the kitchen sink. And that the place has been remodeled a few times and was tinkered with by a “colorful” resident handyman.

To clarify my original question, code would require that the vent is always above the drain? And that reconfiguring it like that would do no harm?

 

[wwhitney]

Because I can confirm that the lower 1.5” pipe is routed out and up the side of the building,

OK, but are you 100% certain that along that route, there are no other connections to the pipe? Because if so, such a pipe is useless and can be removed.

But if one fixture connects to it, then the pipe is serving as a drain for that fixture, and the pipe above the connection would be serving as a dry vent.

The point is that the portion of the pipe shown in the picture can not be serving as a vent. Vents are attached to fixture trap arms before they turn downward, not at some arbitrary elevation lower down in the drain system. Your kitchen sink should have a vent at the elevation of its trap, and it can not be relying on that pipe for venting.

Cheers, Wayne

 

[John Gayewski]

Not sure what's happening here, but there's a possibility that the vent is in the wall and this was supposed to drain a sink and dishwasher or whatever, but someone over time turned the wye. Either that or the op is right and the upper is vent and the lower is trap for drain and someone just cut off the vent pipe at one time.

 

[wwhitney]

this was supposed to drain a sink and dishwasher or whatever

Pretty sure the kitchen is on the floor above, this was described as the basement wall.

Cheers, Wayne

 

[Fogcity]

Pretty sure the kitchen is on the floor above, this was described as the basement wall.

Cheers, Wayne

Yes the kitchen is above. Kitchen sink drain goes through floor and connects to the upper wye branch which terminates in the basement wall as shown in the photo.

Regarding the venting of the kitchen sink, a cheater vent is used inside the sink cabinet. So as a previous poster noted, that drain is already vented and thus perhaps there is no need for any vent and existing setup is fine.