Double wye used for double vanity

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by xr4ti, Aug 5, 2013.

  1. xr4ti

    xr4ti New Member

    Messages:
    26
    Location:
    Wisconsin
    Hello everyone -

    I've been visiting my new home daily as construction progresses, and the rough plumbing started last week. I noticed that they have used double wye's in the upstairs bathrooms, both slated for double vanities. I have seen and used the double fixture fitting in past projects, so I am wondering if there is any difference here? Thanks.

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  2. asktom

    asktom Member

    Messages:
    530
    Location:
    Victor, MT
    It should be a double fixture fitting. A double wye creates a double S trap. A double fixture fitting is made so that air in the trap arm meets the stack before the drain drops down so that a siphon cannot be created. If the trap siphons it breaks the trap seal and there is nothing between your nose and whatever gas is in the sewer. An exhaust fan in the bathroom makes the situation worse.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,516
    Location:
    Cave Creek, Arizona
    Doulbe Ys and 45s create "3/4 S traps" which are just as bad, and illegal, as full "S" traps. The ONLY fitting you should use is the back to back one, and NOT a sanitary cross either. A "plumber" who makes an installation like that has no concept of plumbing hydraulics and should go back to school for a season or two, if he ever went to school.
  4. xr4ti

    xr4ti New Member

    Messages:
    26
    Location:
    Wisconsin
    Thanks for the input, glad I asked here.

    I'll bring this up with my builder tomorrow. Rough inspection is next week and I'm not confident they will flag the fittings.

    Here's another pic. Looks like it's been bouncing around in the bottom of a DWV bin and they finally found a place to dump it. My house!

    Attached Files:

  5. Terry

    Terry Administrator Staff Member

    Messages:
    14,911
    Location:
    Bothell, Washington
    When you combine two lavs, it requires a 2" drain.
    It should have been a 2.0" x 1.5" x 1.5" x 1.5" double fixture fitting.

    So not only is it the wrong fitting, it's also undersized.
  6. Hammerlane

    Hammerlane New Member

    Messages:
    252
    Location:
    Ohio
    Kind of resembles this:

    Attached Files:

  7. Hammerlane

    Hammerlane New Member

    Messages:
    252
    Location:
    Ohio
    A few more

    Attached Files:

  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,516
    Location:
    Cave Creek, Arizona
    ON my screen it looks like a 2" riser with 1 1/2" arms. IF so, it is just the wrong fitting.
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