Question on venting

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by NickM, Jun 10, 2009.

  1. NickM

    NickM New Member

    Messages:
    8
    Hi, I'd like to double check how my venting is for two fixtures. Please see the attached diagram for how I planned on the draining/venting of these two units. I was mainly wondering if I can use the 2" stack for these units as the vent, or if i have to have an additional vent before the p-trap enters the 2" stack? These are the only 2 fixtures on this branch. They connect to a 4" in the basement which also has 2 bathrooms coming into it as well (they have their own venting)

    [​IMG]
  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,413
    Location:
    Bothell, Washington
    When the tub drains, it will siphon the trap on the washer.

    The washer needs either a vent connecting above the tee for the tub, or an AAV to break the siphon.

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  3. nhmaster

    nhmaster Master Plumber

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    3,189
    Location:
    S. Maine
    You can not waste stack vent a washer.
  4. FloridaOrange

    FloridaOrange Plumbing Designer

    Messages:
    1,317
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    SW Florida
    What's your location? IPC requires a 3" up to the washing machine for new construction.
  5. NickM

    NickM New Member

    Messages:
    8
    I'm in Pennsylvania, Altoona to be exact, so we'd be under city codes. I'm assuming by up to the washing machine, you mean a 3" stack up to the 2" p-trap for the washer?
  6. FloridaOrange

    FloridaOrange Plumbing Designer

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    1,317
    Location:
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    Yes. I don't know how/if it applies to your case, just bringing it up in case it does. 3" up to 3x2x2 tee. 2" trap, 2" vent.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    vent

    Regardless, the drain pipe from the upstairs cannot be used as a vent for the downstairs washing machine. And an AAV would only take care of half the problem with doing it.
  8. NickM

    NickM New Member

    Messages:
    8
    Ok, so here's what I derived from the responses. This would be correct then?

    [​IMG]
  9. Redwood

    Redwood Master Plumber

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    Connecticut
    Looks good to me.
  10. Terry

    Terry Administrator Staff Member

    Messages:
    15,413
    Location:
    Bothell, Washington
    To be even gooder, the vent could tie in above the fixture flood level on the second floor.
    The inspectors like to see that at 6" above the highest fixture.
  11. kingsotall

    kingsotall Plunger/TurdPuncher

    Alright, now we're talking like folks from around these parts! :cool:
  12. NickM

    NickM New Member

    Messages:
    8
    What's going to be tricky is that both the drain and vent are coming up through the same 16" stud spacing, under a 8" floor. The vent is going to have to turn and go through a floor joist to continue up the 2nd floor wall to the attic. I'm sure I can get 6" more inches of pipe from the top of the drain to meet the vent, but it's going to be tight. Unless I take bends off of the vent AND drain and have them meet higher up in the 2nd floor wall.

    Another question, for the vents coming off of the p-traps, do I use a sanitary tee, a wye with a 45, or just a regular tee? And where the p-trap connects into the stack, I was planning on using a sanitary tee, if that was correct as well.
    Last edited: Jun 11, 2009
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    vents

    The code reads that the connection between the two vents has to be 36" OR 6" above the highest fixture whichever is HIGHEST. This is to prevent problems in case someone decides to connect a 36" high kitchen sink to the system some day. A Y with a 45 pointing downward will give the closese separation, the tee is the proper fitting for the connection to the drain, but since it wll have its own vent you are not limited to the tee, but can use any connection that works for you. You could use another Y with a 45 faced upright, then a tee in the vertical line which would place the vent as close to the drain as possible an it would be aligned with the upstairs vent so you would have a straight pipe between them.

    [​IMG]
    Last edited by a moderator: Jun 2, 2010
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