Is this an S-trap from my bathtub drain?

[Gunn1]

I'm building an addition on my home, mostly DIY. I hired a plumber to do the DWV, while I did the hot/cold water. I had a lot of issues with him along the way. I started drywall but before I covered any of the PVC, I wanted to test the system (not code required in my county). I installed plugs, and filled it up. Tons of leaks...everywhere...

So now I'm ripping out all of the old stuff to fix it, myself. I came across this under my standard bathtub drain. The 3" pipe is the main drain line. The other end of the trap runs to the tub drain. So, would this be considered an S-trap??! If so, I want to fix it now.

The closest vent for this tub is a few feet away that also serves as the vent for the double lavatory.

I'm thinking I need to add a vertical vent in this trap arm, at least...?

Thanks,

Tom

 

[Smooky]

It is an s-trap and not the correct way to do it.

 

[Sponsor]

 

[Reach4]

I'm thinking I need to add a vertical vent in this trap arm, at least...?

Right. That will turn it into a P trap rather than an S trap.

I think you could replace the elbow with a sanitary tee if you could then take the vent up from there. I don't know how much you are allowed to tilt a santee.

 

[Gunn1]

I figured this was an s-trap!...I even had the county inspector come after the plumber left the first time and I saw all kinds of issues. I had to have the plumber come back out and rip out a bunch of stuff to fix it, but I missed this one. And the inspector obviously didn't notice either. And now I have to rip it out again anyway because nearly every joint leaked
Anyway, a sanitary tee coming off the output of the trap would be ideal, but that won't work for me as even if it does line up with the wall, I have the hot/cold water lines and the valve right there above the tub. So I need to offset the vent to the side of the tub. I think I can run the trap arm less than a foot, then into a sanitary tee to go vertical for the vent, and down into the drain.

Just as a general question, is it permissible to use a combo-wye in the trap arm to place my vertical vent?

Thanks,
Tom

 

[hj]

he combo, used properly of course, is the fitting you SHOULD use to connect the vent, but NOT in place of the elbow.

 

[Cool Blue Harley]

he combo, used properly of course, is the fitting you SHOULD use to connect the vent, but NOT in place of the elbow.

The combo is NOT the fitting you should use to connect the vent. In vertical installations, the sanitary tee is the proper fitting to use for this connection. A combination wye and one-eighth bend or a wye will not be allowed here since the opening of the vent would be below the weir of the trap.

A vent pipe connection that is below the weir of the trap allows the potential for the fixture to induce self-siphonage.

 

[Reach4]

In vertical installations, the sanitary tee is the proper fitting to use for this connection.

In that bottom part I think Gunn1 was talking about a vent in the horizontal part with the water staying horizontal at that point, and the vent leg would go vertical.

Just as a general question, is it permissible to use a combo-wye in the trap arm to place my vertical vent

It is the "in the trap arm" that seems to say that as I read it.

 

[Cool Blue Harley]

In that bottom part I think Gunn1 was talking about a vent in the horizontal part with the water staying horizontal at that point, and the vent leg would go vertical.


It is the "in the trap arm" that seems to say that as I read it.

Thank you for pointing that out Reach.

Well yes. However, the combo would not be in the trap arm because, technically, the trap arm is the pipe between the trap weir and the inner edge of the vent.

 

[Gunn1]

Thanks for the explanations. I need to clarify, and I apologize for my terminology!

I was thinking that if I could come off the trap, and in that ~10" horizontal piece (properly sloped of course), I could place a combo-wye there to line up with the wall above, the one outlet pointing vertical for my vent up through the subfloor and through the wall. The other end of the combo-wye would be the drain and could then run down into the main line.

But I may be able to use a sani-tee also, but it would be placed somewhere in that ~10" horizontal piece, so I could get it to line up with the wall above, not directly at the end of the trap.

Thanks again,

Tom