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Thread: Proper double sink waste plumbing, with Disposer?

  1. #1
    DIY Junior Member Rock51's Avatar
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    Default Proper double sink waste plumbing, with Disposer?

    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
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    AFTER
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    Last edited by Rock51; 04-26-2009 at 12:26 PM. Reason: Forgot an important item

  2. #2
    Plunger/TurdPuncher kingsotall's Avatar
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    Default

    Hope you don't mind that I used the first pic as an example of how to arrange their pipes in another thread...
    I just post cuz I like to see my avatar.

  3. #3
    DIY Member Marty53's Avatar
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    Default ..

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

  4. #4
    Forum Admin, Expert Plumber Terry's Avatar
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    Default

    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. #5
    DIY Junior Member Rock51's Avatar
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    Default 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. #6
    Moderator & Master Plumber hj's Avatar
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    Default 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. #7
    DIY Junior Member Rock51's Avatar
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    Default 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. #8
    Master Plumber Redwood's Avatar
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    Default

    I find that tubular properly installed will stay in place just fine...

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