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1 1/4 instead of 1 1/2 for kit drain OK?

MBaybut | Posted in Energy, Heating & Insulation on August 4, 2006 02:41am

Hi,
It was suggested I post this here. The saga continues. I’ve moved my kitchen sink across the opposite side of the kitchen and now I’ve just found out that the drain line I was going to tie it into is 1 1/4″ (copper) and not the 1 1/2 I thought it was. It’s basically kitchen sink, then a vanity then into the stack, approx 10ft run total. Will it be OK to go ahead and hook it up. Speaking from a functional issue and not a code issue.
Thanks,
mike

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  1. User avater
    johnnyd | Aug 04, 2006 04:57pm | #1

    Of larger concern is where the vent is in relation to the kitchen sink and vanity.  Is it vented at all?  Non-vented long kitchen drain lines are legendary for gradually clogging up, so from both a code and functional view point, you're not in the best shape.

    Sounds like you're going to go ahead and do it anyway....but I would really look into the vent issue and maybe go for a Studer vent.

    http://www.studor.com/



    Edited 8/4/2006 10:00 am ET by johnnyd

    1. DanH | Aug 04, 2006 05:07pm | #2

      And if you decide to go ahead anyway, make sure you install easily-accessible cleanouts.
      If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison

    2. MBaybut | Aug 04, 2006 08:41pm | #5

      Thanks to all for the rapid response. I took the advive from one of the previous "helpers" and decided to do it right. I pulled all the plaster from the walls all the way to the stack. I completely removed the old 1 1/4", what a bear of a job, and have now a fairly straight forward job of running the new 1 1/2 drain to the stack. Is the venting still going to be an issue. The 4" stack is about 8-9 ft away, with the vanity drain about in the middle. Thanks again for all your help.
      Mike

      1. User avater
        johnnyd | Aug 04, 2006 08:58pm | #6

        If you really want to do it right, you'll run a vent pipe up out of the horizontal run as close as you can to where your P trap connection is and then elbow over to the stack, connecting with a sanitary tee in to the stack.

        Will your drain still work if you have an un-vented 8 - 9 ' run?  Probably OK, but as long as you've done the demo work, why not run 2" instead of 1 1/2".  That will work better.

        Actual plumbers will chime in here I'm sure.

        1. MBaybut | Aug 05, 2006 02:08am | #7

          Johnny,
          Yes, the only problem was T on the cast iron stack was only a 1 1/2". Can you still go 2" and the finish off in the T at the stack 1 1/2 ?
          Mike

          1. User avater
            johnnyd | Aug 07, 2006 03:08pm | #8

            The 1 1/2 will still be a bottleneck.  Any thing stopping you from cutting into the cast, and putting in a 3 X 2 X 3 PVC sanitary T with Fernco or similar couplings? 

            The 1 1/2 " will probably be OK, it's just that kitchen sink drain lines are usually 2" because of the increased number of solids they have to handle.  In any case, put a nice clean out in so you snake these lines out if you ever need to.

        2. DoRight | Aug 07, 2006 06:43pm | #9

          8 or 9 foot run without  a vent in there?  Sounds like a receipe for a dry P-Trap (siphon effect).

          1. User avater
            johnnyd | Aug 07, 2006 06:57pm | #10

            I know...that's why I'm trying to get him to properly vent it.  I've actually done a vent-less run almost that long with no dry trap effect...but I think I was just lucky.  Also, isn't 2" less suseptable to that than 1 1/2?

  2. Brian | Aug 04, 2006 05:13pm | #3

    I don't know if 1-1/4 will be sufficient or not, probably mostly just inconvenient (slow draining), but is it possible to drop a 1-1/2 line with a AAV (Studor) at the top and then reconnect to the same stack below your floor level?

     

     

    Treat every person you meet like you will know them the rest of your life - you just might!
  3. Shacko | Aug 04, 2006 06:06pm | #4

    Bad idea no matter what the code says, line will be over-loaded.

  4. Shacko | Aug 07, 2006 07:12pm | #11

    I agree with one of the other posts, while you have the wall open put in a 2in. line, if you ever plan to install a disposal the 1 1/2will be too small. You need to run a vent as close to the trap as possible; do it now or have probs. in the future. Lots of luck.

  5. Mooney | Aug 07, 2006 08:00pm | #12

    Yes it will work but it may be slower than normal. Does this require a dish washer too? If it does Im doubting it . Theres a lot of difference in the two pipes for flow. More than it sounds like . Someone will probably post the difference as theres a link to it somewhere.

    And no its not code accepted .

    Tim

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