Dishwasher wye on horizontal pipe OK?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by bruceha2000, Nov 13, 2013.

  1. bruceha2000

    bruceha2000 New Member

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    Vermont
    Hi all,
    I am reinstalling a wall hung 1949 American Radiator (that would be before they became American Standard) sink after a remodel. The plumbers put the drain pipe in the wall to the right of where the right hand basin drains JUST far enough off that I have to T off the bottom of the right side (shallower) sink tailpiece rather than directly into the trap. I am fussing with options on where to put the dishwasher wye pipe. The dishwasher is to the left of the left side (deeper) sink and there is not enough vertical room for the dishwasher wye tailpiece. It WILL fit under the right side sink but I'm wondering if putting it horizontally is a better option. I need an intermediate union in the horizontal pipe anyway since the center line of the sink drains is 19".

    The picture is an "in process" and I've not cut the tail piece for the left sink yet. What you see is a REALLY short piece that was in the right side tailpiece when we bought the house. The left sink T'ed into the right tailpiece (with dishwasher drain) and yeah, we had the "bubbly soapy water" problem. I'm hoping that since I have to T to the trap anyway, we'll have less of that now. If I put the dishwasher wye in the horizontal pipe, I think I would attach it to the elbow that will go on the bottom of the left sink tailpiece rather than into the T under the right side sink but could easily be convinced that having it more in the center of the pipe would be better.

    Reasoning to put it in the horizontal pipe:
    1) closer to the dishwasher
    2) Will "shoot" directly into the pipe that goes into the trap instead almost horizontally into the tail piece of the right side sink, then having to make the 90 degree turn to horizontal.

    Are there reasons I should NOT put it in the horizontal pipe?

    PB130060.jpg

    Also, in case anyone knows (American Standard doesn't):

    Is this the proper location under the sink for the spade top of the adjusting screws for the cast iron legs that support the front of the sink? There is one outboard of each sink, a few inches back from the front. The screws drop into the top of the leg where there is a shaped space to "hold" the nut. I would expect something that was a "tight" fit slot but this is the only area I can find that even comes close. Or, perhaps, there was (long ago) some piece of something that had such a slot that fit into this area under the sink??

    BTW, the wood framing under the sink in the picture was just to get it in position (it is HEAVY!) to mount it on the wall. I have the legs installed and the sink is no longer resting on the wood but I figure it is like a jack stand while I am working under the sink since there is no tight connection for the legs. I'd hate to knock one out and have the sink potentially crash down on me.

    PB090039.jpg PB090047.jpg

    Thanks,
    Bruce
     
  2. cacher_chick

    cacher_chick Test, Don't Guess!

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    I would install the dishwasher tee on the right sink. You should not have the tee turned onto it's back. The right sink should drain vertically through the tee and straight down into the trap.

    The proper end outlet continuous waste with dishwasher kit will place the DW connection below the inlet of the other sink, and above the trap.

    [​IMG]
     
    Last edited by a moderator: Nov 14, 2013
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  4. Sean Beck

    Sean Beck Plumber

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    Yes, you can install a dishwasher 'wye' on horizontal pipe, but that is not a dishwasher 'wye'. That is a dishwasher tailpiece that is made to attach to the basket strainer of the sink vertically. Having the fitting the way you have it will cause the discharge from the dishwasher to shoot up into the left hand compartment of the sink.

    I would do one of two things. Either attach the tailpiece to the right hand sink compartment vertically, or use a proper dishwasher 'wye'.

    http://www.homehardware.ca/products/300/32537301.jpg
     
  5. Tom Sawyer

    Tom Sawyer In the Trades

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    You can't install the tailstock in that position. Put in on the bowl on the right.
     
  6. bruceha2000

    bruceha2000 New Member

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    It isn't a tee but a wye and it does have a baffle in the pipe to direct the water to the right (in this configuration). But locating it under the basket in the right side sink is the alternate solution and the hose from the dishwasher is long enough to install it there.

    I wish. However, as I said, the plumbers put the drain pipe just far enough to the right that the tail piece can't go into the trap and therefore, neither can the tee. I know that isn't obvious from the picture. Anything that would bring the outlet pipe to the left would bring it too far because of the small distance I actually need it to go and water from the right sink would have to go left to get to the trap and then right to get to a 90 going left into the outlet pipe. Plus I would be "asking" the water from the left sink to hang a hard left which would necessitate a pipe wye to send it that way. Otherwise, I'd have water sitting in the bottom of the connecting pipes. Lots of changes in directions which I think would be much worse for water flow than the T on its back. Perhaps there is a "street" tee made of this thin wall slip tubing? I know that would be better than a regular tee.

    The bottom of the left sink is 6" lower than the bottom of the right sink. It is too low for the suggested kit relative to the height of the pipe in the wall and the trap. Total distance between the bottom of the left sink basket threads and the top of the elbow on the trap is 2.5". Thus, if the DW wye is vertical, it has to be attached to the right sink above the connecting pipe rather than below.

    Bruce
     
  7. bruceha2000

    bruceha2000 New Member

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    Do they make such a thing in thin wall slip pipe? I don't think I want to be bouncing back and forth between sched 40 and thin wall.

    Bruce
     
  8. sjsmithjr

    sjsmithjr In the Trades

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  9. cacher_chick

    cacher_chick Test, Don't Guess!

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    The root of the problem is that the sanitary tee in the wall is not located where it should be given the position of the sink.

    You might find it possible to use a combination of 1/16 bends and or 1/8 bends to properly align the trap arm with the trap. A tee on it's back is never a correct solution.
     
  10. Tom Sawyer

    Tom Sawyer In the Trades

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    I would just use a glued up P trap. Problem solved
     
  11. sjsmithjr

    sjsmithjr In the Trades

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    Not to muddy up the waters but maybe I'm missing something. Although unconventional there is nothing that precludes installing the dishwasher tailpiece (green circle) on the horizontal as long as it is before the trap. The "tee" on the right basin, however, is installed incorrectly and should be rotated 90 degrees to be in a vertical position.

    PB130060.jpg

    If the OP rotates the slip tee (red circle) to the correct position and shortens the tailpiece on the right basin it should all still come together correctly. A 1/16 or 1/8 bend might be needed coming out of the wall but it looks like he has the pipe to do it. As long as the trap is lower than the deeper of the two basins it doesn't matter how short the tailpiece on the left is, although it looks like it will be longer than it was in the original installation. I've seen no mention of a disposer, which would seem to be out of the question without lowering sanitary tee in the wall. Am I missing something?

    -Sam
     
    Last edited: Nov 14, 2013
  12. cacher_chick

    cacher_chick Test, Don't Guess!

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    Sorry if i wasn't clear- That is what I was referring to.
     
  13. bruceha2000

    bruceha2000 New Member

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    OK, where does one get a 1/16 or 1/8 bend? I've seen only 90s and 45s. And no, there will be no disposal, good thing the wife doesn't want one ;)
     
  14. sjsmithjr

    sjsmithjr In the Trades

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    1/16 bend = 22.5 degrees and a 1/8 = 45 degrees. Available just about anywhere (SCH 40). Try rotating the slip tee and trimming the tailpiece first. You may not need them.

    -Sam
     
  15. bruceha2000

    bruceha2000 New Member

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    Thanks Sam. Some time after I posted the question I figured out those bends were probably sched 40, not thin wall. I just happen to have a couple of 1/16ths left over from plumbing my prior house 20 years ago so I can mess about.

    It looks like I should be able to line things up ... just ... if I:
    - cut the sched 40 drain pipe in the wall back some
    - install a 1/16th bend facing left toward the right side sink
    - get an end outlet waste T to connect into the trap

    There shouldn't be too much of a turn going from the trap to the bend, I've seen a lot worse in my recent searching but I bet they don't work well . Off to the store (again).

    And while I originally thought that having the DW jet into the connecting pipe would help move things along with fewer bends, I'm now thinking that might invite solids to build up there even with decent pitch. So, back to the "normal" vertical configuration with the DW tailpiece under the right side sink where it will probably be noisier and possibly force non dishwasher soap bubbles that may be in the tail piece back up into the sink. I've seen this before which is why I wanted to put the DW wye on the horizontal where the water would be "pulling" any said soap bubbles to the trap since it wouldn't be trying to displace what is in the tail piece.

    Bruce
     
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