Rich wrote:

Speedy Jim wrote:

Rich wrote:

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.


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:
http://www.plumbingsupply.com/autovent.html

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

Jim


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?


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