Kitchen drain quandry/issue?

[Rich]

Hi,

After receiving great opinions with my insulation question, I thought I pose another problem I'm having.

I currently have what's called an unvented 's' trap under my kitchen sink. To me, it doesn't look quite an 's' trap but a hybrid of a 's' and 'p' trap. I'm having major drainage issues from this sink, and am considering my options. Also, I am converting from a conventional mounted sink to an undermount sink (replacing with granite). AND I have a diswasher attached to the drain (which backs up during the dishwasher cycle) To describe the look of the drain-- it leaves the sink straight down, hits the elbow, returns up and flattens out for about 4" and then turnd down to the drain in the floor. It also appears that the pipe running from the sink to the floor drain is 1

1/4", because I measured the outer diameter and it is 1 1/5" and it is converted to a larger pipe in the floor drain (I think 1 1/2" or 2") via a rubber coupling.

My question is, how can I make this into a genuine 'p' trap so it's 1. legal and 2. better draining. Also, with an undermount sink, will there be major issues with the drainage? Should I replace the smaller drain with a larger diameter pipe?

Thanks for the help.

[Speedy Jim]

I don't know if you'll have the room under the sink but coming down from the sink drain, go into a tubular dishwasher "WYE" and then into a 1 1/2" P Trap.

Have the P Trap enter a 1 1/2" TEE (side). Bottom of TEE goes down to drain. Top of TEE has short riser to a mechanical vent, like one of these:

If the existing drain (under floor) is clogged, you will continue to have backup problems and the drain needs to be snaked.

Jim

[Rich]

Thanks Jim for the info.

I actually have the WYE (not sure what size). I had already purchased the stuff to make the TEE and autovent but was concerned about the space under the sink. I have to wait until the new sink is installed and then see what space I have left, I guess.

Thanks again. Rich

[Rich]

Another question,

Since 's' traps are now not acceptable, and my drain is set p into the floor, can I still make a 'p' trap work?

[Speedy Jim]

As described above, the auto vent will make the P trap function.

If the vertical drain thru the floor is actually 2" size, it used to be permissible to terminate it in a 2 X 1 1/2" reducing EL. The P Trap simply goes into the EL. This arrangement provides for *some* circulation of air in the larger 2" pipe and prevents trap siphonage without the use of a "real" vent.

Jim

[Speedy Jim]

As described above, the auto vent will make the P trap function.

If the vertical drain thru the floor is actually 2" size, it used to be permissible to terminate it in a 2 X 1 1/2" reducing EL. The P Trap simply goes into the EL. This arrangement provides for *some* circulation of air in the larger 2" pipe and prevents trap siphonage without the use of a "real" vent.

Jim

[Rich]

Thanks again for the info. Since I think the vertical drain is 2", can I use that to my advantage and make more of the pipes in the trap, etc.

2" Or do they need to be 1 1/2" opening to 2"?

Since the water is draining slowly, I thought about using both the vent device and 2" pipe.

Thoughts?

Rich

[Speedy Jim]

The P-trap will be 1 1/2" tubular size to match the sink.

Yes, you can use the auto vent and the 2" drain.

While you have it all disconnected, strongly advise to snake the vertical drain. Then set up either a garden hose or a big funnel and bucket to flush it out and see that it drains properly.

Jim

[Rich]

Thanks Jim...I will definately try that. I guess my biggest concern is the space under the undermount sink. If it is tight, what can I do to make it as efficient as possible?!? Can I make the drain go off to the side, then down, etc.?

Rich

[Speedy Jim]

I wouldn't put an elbow in the sink tailpiece. The P-trap can be placed down as low as cabinet base level, as long as it can be dis-assembled later. If needed, you could saw off the vertical drain and put the rubber coupling on to join. Jim