Thread: Trap 2-fer

Found a 2-fer today. Two P traps sharing a single vent under the kitchen sink AND an S trap in the master bath.

I guess you could call it a 3-fer since the dishwasher did not have a high loop before it emptied into the garbage disposal using the shared vent between the 2 P traps.

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I do not see a problem having two traps.

The trap in the third picture in the bath looks okay too. They used a P trap and PVC 90^. How else could it be done?

With an aav so that it's vented.

Good point....

Originally Posted by Rick Cantrell

I do not see a problem having two traps.

The traps share a single vent. One could siphon the other dry.

Originally Posted by Rick Cantrell

I do not see a problem having two traps.

There are two trap arms shown, one from the vent out to the right and one from the vent out to the left, that is allowed.

Originally Posted by James Duffin

The trap in the third picture in the bath looks okay too. They used a P trap and PVC 90^. How else could it be done?

Originally Posted by John Goad

With an aav so that it's vented.

The third photo is an 'S' trap and is not allowed, the easy correction is an AAV as John said (and James added as a "Good Point").

Disposal should have a air-gap device or high loop

Originally Posted by John Goad

With an aav so that it's vented.

Newbie question: What's an AAV? Thanks. Enjoy reading the forum.

Originally Posted by Mitchell Chiger

Newbie question: What's an AAV? Thanks. Enjoy reading the forum.

Air Admittance Valve.

Originally Posted by Jerry Peck

...The third photo is an 'S' trap and is not allowed, the easy correction is an AAV ....

If an AAV is allowed. They're not in Philadelphia.

In the third picture I was thinking the vent was not visible...like it was vented like an island sink would be.

In the third picture I was thinking the vent was not visible...like it was vented like an island sink would be."

An island sink, like this one, should have a loop vent, however, in most areas an AAV is allowed.

I have seen wet venting allowed on island sinks but if the pipe is not sized properly it can siphon the trap.

Originally Posted by Rick Cantrell

In the third picture I was thinking the vent was not visible...like it was vented like an island sink would be."

An island sink, like this one, should have a loop vent, however, in most areas an AAV is allowed.

Not an island sink. Master bath sink as stated in original post. Located on second story with direct access to roof with no obstructions to prevent installation of a vent to the exterior. Master bath was an 2004 bump out addition to a 1971 split level.

Maybe I was not very clear in my wording.
I should have said:
An island sink, as well as this one, should have a loop vent,...

Originally Posted by James Duffin

In the third picture I was thinking the vent was not visible...like it was vented like an island sink would be.

Nope, that is a plain old (or new) 'S' trap.

Originally Posted by Rick Cantrell

I should have said:
An island sink, as well as this one, should have a loop vent,...

An island sink COULD have an AAV (where AAVs are allowed, which is most, but not all, places).

Have it fixed by someone who not only understands drainage, but also venting.

Ya just gotta wonder sometimes.

100 yr old house coverted into apartment building. "Plumber" used the same technique in all 4 kitchens.

Two bowl kitchen sink. Individual traps on each bowl T'ed into a single pipe that goes down and and out but no vent. Do these become doubled S traps?

Since the two traps share a pipe before they exit and there is no visible vent, then this is not a valid configuration?

Originally Posted by Paul Johnston

Air Admittance Valve.

Thanks, Paul.

Bruce
Pics 1,2,&3, are S Traps. Pic 4, I cannot tell, it looks like ot goes into the wall, so it could be vented.