Proper double sink waste plumbing, with Disposer?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Rock51, Apr 26, 2009.

  1. Rock51

    Rock51 New Member

    Messages:
    5
    Location:
    Washington
    Greetings,

    Before I found this forum and read some of the good threads, I re-plumbed the waste lines under my double kitchen sink. The tubular drain fitting attached to my Insinkerator came loose one time and made a big mess. And I did not prefer the usual baffled T-fitting for the disposer drain line, since I believed it constricted the flow from the disposer and made it work harder than it had to. The photos show the Before and After of my project. I'm interested in your feedback. Thanks in advance.

    BEFORE
    Before small.JPG

    AFTER
    After small.JPG
    Last edited: Apr 26, 2009
  2. kingsotall

    kingsotall Plunger/TurdPuncher

    Hope you don't mind that I used the first pic as an example of how to arrange their pipes in another thread... :)
  3. Marty53

    Marty53 New Member

    Messages:
    44
    Location:
    New York
    ..

    I don't think thats the correct usage of a combo wye.. you should use a san T in that application.
  4. Terry

    Terry Administrator Staff Member

    Messages:
    14,904
    Location:
    Bothell, Washington
    That will work in your case.
    Since it's the p-trap that needs venting, and not the continuous waste, that combo fitting is fine.

    If you can pull up the black rubber tubing from the diswasher so that it drains down into the disposer, that would be a good tweak.
  5. Rock51

    Rock51 New Member

    Messages:
    5
    Location:
    Washington
    Why isn't ABS used more often under kitchen sink?

    Thanks, everyone, for your comments.

    I would like to raise the DW drain hose, as Terry suggests, but how to do that? Where would I attach a hanger, since there's only cast iron sink above the loop? I guess I could install a hanger toward the back of the sink instead and raise the DW drain line in general, which would tend to raise the loop. What should I use for a hanger?

    Also, the DW drain hose is somewhat compressed in the loop (oval cross section instead of circular), because of the relatively small radius loop. I was concerned about restricted flow and that the DW drain water might back up out of the air gap. But the DW seems to drain just fine. Anything to be done here? Should I switch to a different hose that can be bent in the tight loop but stay round in cross-section?

    What do you think about my ABS/tubular mix under the sinks instead of all-tubular? (I go this idea from McLendon's Hdw (Seattle area) years ago.)

    I found that the tubular stuff, with so many hand-tightened joints, tended to loosen up over time. The ABS takes more work to install but it's really solid. The biggest problem is that the only available ABS p-trap has a threaded joint on just the sewer side. So, if I ever have to get to the trap, I have to loosen 3 threaded joints and remove all the ABS as one unit. Awkward but do-able.

    Thanks.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,508
    Location:
    Cave Creek, Arizona
    drain

    What you have will work, the only problem is that "locknut joint" on the "P" trap outlet has a tendency to crack and/or strip.
  7. Rock51

    Rock51 New Member

    Messages:
    5
    Location:
    Washington
    How to hang DW hose? Is hose OK with tight bend?

    I would like to raise the DW drain hose, as Terry suggests, but how to do that? Where would I attach a hanger, since there's only cast iron sink above the loop? I guess I could install a hanger toward the back of the sink instead and raise the DW drain line in general, which would tend to raise the loop. What should I use for a hanger?

    Also, the DW drain hose is somewhat compressed in the loop (oval cross section instead of circular), because of the relatively small radius loop. I was concerned about restricted flow and that the DW drain water might back up out of the air gap. But the DW seems to drain just fine. Anything to be done here? Should I switch to a different hose that can be bent in the tight loop but stay round in cross-section?

    Thanks.
  8. Redwood

    Redwood Master Plumber

    Messages:
    7,452
    Location:
    Connecticut
    I find that tubular properly installed will stay in place just fine...
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