S-Trap or P-Trap

[Joe Funderburk, CMI]

The top arm of this trap is about 4" horizontal. Feeds into a vertical drain. The horizontal run is short because they put the drain (and supply lines) in the center of the cabinet instead of at the back. When does an S-trap become a P? What does the length of horizontal pipe need to be?

Thanks for your help.

[Ted Allen]

That is the popular,but little known "O" trap.

[Ted Allen]

I would say it needs some fixin'.

[Jeffrey R. Pope]

Looks like an attempt at a "verticle leg" fixture drain. (See IRC P3105.3)

The trap arm is required to be a minimum of 8 inches.

[Jay Moge]

looks newer too. bet there's a P trap under the floor. if not then that's an S trap and needs to go.

[Jeffrey R. Pope]

Originally Posted by Jay Moge

looks newer too. bet there's a P trap under the floor. if not then that's an S trap and needs to go.

Double trapping is not allowed. The picture shows an improper S trap.

[Joe Funderburk, CMI]

Originally Posted by Jay Moge

looks newer too. bet there's a P trap under the floor. if not then that's an S trap and needs to go.

House is on a slab. Nothing but this as a trap.

[Jay Moge]

Originally Posted by jpope

Double trapping is not allowed. The picture shows an improper S trap.

DING DING DING... Your rignt again Jeff. I alway look for the posability of a trap under the floor, because i missed one once and it came back on me when they called the plumber to install a trap and he found it in the basement between the joists. luckily i knew him and he didn't charge.

[Jay Moge]

Originally Posted by jfunderburk

House is on a slab. Nothing but this as a trap.

yup. S trap, as Jeff concured. it's gatta go. reroute and install proper P trap.

[Joe Funderburk, CMI]

You all confirmed what I thought. Still in my fist year. Thanks a bunch.

[cbuell]

The trap arm appears to run to a sanitary t----is there an air admittance valve above the sani-t? If so then the trap arm length would be the biggest issue and it would be a P-trap. Minimum trap arm length is supporsed to be 2xPipe diameter.

[Joe Funderburk, CMI]

Originally Posted by cbuell

The trap arm appears to run to a sanitary t----is there an air admittance valve above the sani-t? If so then the trap arm length would be the biggest issue and it would be a P-trap. Minimum trap arm length is supporsed to be 2xPipe diameter.

There is an air admittance valve above the sani-t. Please clarify how that makes this OK (I think that is what you are saying). Can you cite the code please for my reference?

[Ted Allen]

I think the air admittance valve is supposed to keep it from siphoning the trap dry, but I still don't like it.

[cbuell]

Most jurisdictions now allow air admittance valves. If the pipe and vent were buried in the wall how would it be any different than this set up with the valve (except for the short trap arm)?

[Ted Allen]

I may be wrong here, but don't most island sinks and MH's use an air admittance valve, and still have a proper P-trap installed?

I am confussed.
Help me to understand.