p trap plumbing question. pic included.

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by aharami, Dec 20, 2013.

  1. aharami

    aharami New Member

    Messages:
    21
    Location:
    New Jersey
    Is this legal? Existing 3" pipe is the vent.
    IMAG1066.jpg
    IMAG1068.jpg
    Water is draining from right to left in existing 3" pipe currently. I want to connect new shower drain to this pipe. Location of shower pans drain won't give me enough space to install p trap right to left because of existing 3" fitting.
    Last edited: Dec 21, 2013
  2. aharami

    aharami New Member

    Messages:
    21
    Location:
    New Jersey
    I guess what I'm asking is if drain water always has to flow in one direction? Or can the p trap take the water to the right and then connect to a main pipe where the water is flowing to the left.

    Appreciate your help.
  3. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,359
    Location:
    Yakima WA
    Not legal. You have an S trap. You must have a vent in the area where you left hand is located in the first photo. That's before the pipe turn downward.
  4. aharami

    aharami New Member

    Messages:
    21
    Location:
    New Jersey
    Oh, that 3" pipe is the main vent stack. That existing 1.5" wye you see in the 2nd pic is for the old tub drain. I'm moving the drain from a right hand configuration to a center configuration. Past that existing wye, to the right, the 3" pipe makes a 90 degree turn upward and vents out the attic.

    After I posted this thread, I read that a p trap must have a horizontal section after the weir. So if I take the p trap to the right, then have a horizontal section for 6", then make a 90 degree turn downward toward the 3" pipe, then connect it to the new wye via a 45 turn angled down appropriately so it meets the new wye, is that legal?
    Last edited: Dec 21, 2013
  5. Tom Sawyer

    Tom Sawyer In the Trades

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    Location:
    Maine
    Where's the vent?
  6. aharami

    aharami New Member

    Messages:
    21
    Location:
    New Jersey
    The vent would be the 3" pipe I'm connecting it to. That 3" pipe runs to the right, then goes up to vent out of the attic.
  7. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,249
    Location:
    Land of Cheese
    No. The fixture vent MUST rise vertically off the trap arm, and must remain vertical until it reaches a point at least 42" above the floor, or 6" above the flood rim of the highest fixture served, whichever is greater. No section of the vent may be horizontal before the minimum height is reached.

    Time to rethink your plan.
  8. aharami

    aharami New Member

    Messages:
    21
    Location:
    New Jersey
    So how are shower drains plumbed then? If the vent must rise vertically directly off the p trap and the p trap is in the center of a 5'x3' shower pan...how is that possible? The shower pan won't allow the vent to rise vertically directly off the p trap which will be under the center of the pan. Confused...
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,831
    Location:
    Cave Creek, Arizona
    The pipe from the trap to the vent connection, wherever that is, MUST be horizontal, (other than the slope due to pitch), It cannot turn up OR down until then, and your pipe appears to turn downward into the "Y". Also, if there is a toilet 'upstream" from the shower connection, that is also illegal unless the shower has its own dedicated vent.
  10. aharami

    aharami New Member

    Messages:
    21
    Location:
    New Jersey
    Ok so this is all existing plumbing. That wye in the center of the pic is where the old tub was plumbed to. As you can see, the p trap arm was connecting directly to a horizontal vent pipe. My new shower drain location has to be where that elbow is sitting on the ground. The farthest to the left I can cut the 3" pipe is 1.5" to the right of wye on the left of the pic. How would I go about connecting the p trap properly so that everything is legal? IMAG1072.jpg
    Last edited: Dec 21, 2013
  11. aharami

    aharami New Member

    Messages:
    21
    Location:
    New Jersey
    Ok thanks for that. I'm getting it now. So if I run the p trap left to right but make it so that the arm is same level as vent pipe, have a horizontal run for about 6 or so inches, then pretty much make an u turn using a 90 and a 45 to connect to the new wye, would that be ok? Something like this drawing. Pardon the horrible diagram. View attachment 22747

    Toilet connection is downstream to shower. Still don't understand how I'm supposed to have a vertical vent directly off the p trap arm. I guess the existing plumbing wasn't done to code...or maybe the code changed in the past 20 yrs.
    Last edited: Dec 21, 2013
  12. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,227
    Location:
    Maine
    I see what you have there now. What you are trying to do is to pipe a fixture into the house stack. You can't do that. You need a separate stack that runs all the way to below the fixtures on the first floor.
  13. aharami

    aharami New Member

    Messages:
    21
    Location:
    New Jersey
    What is the reasoning behind that? As long as everything is joined properly, vent is vent, no?
  14. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,227
    Location:
    Maine
    No vent is not vent. That stack serves the fixtures below it. If you use it the way you are trying to use it, you would need to re-vent all the lower fixtures to a point above the flood level rim of the 2nd story fixtures. In short, you can't tie into that 3" pipe with waste water. You need to run a separate 3" pipe all the way to probably the basement and tie into the waste there. Absolutely do not continue to do what you are doing or you will have big problems.
  15. wjcandee

    wjcandee Wise One

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    Location:
    New York, NY
    Last edited: Dec 21, 2013
  16. aharami

    aharami New Member

    Messages:
    21
    Location:
    New Jersey

    Thank you for the links and thank you for taking the time to educate such a novice like me. One thing I'm trying to understand is if this is such a big no-no, then how was the old tub draining into this stack without causing problems? I'd assume the builder of this townhouse would've needed to build it all to code, albeit 20 yrs ago. By no means I'm saying you guys are wrong, but maybe with my limited knowledge, I'm not explaining things correctly.

    Btw, only fixtures on first floor is a toilet, bathroom sink and kitchen sink.
  17. aharami

    aharami New Member

    Messages:
    21
    Location:
    New Jersey
    I just went up to the attic to check how everything is vented, and this 3" pipe is the main vent stack. But from this pipe, there is a 2" vent offshoot going into the second bath. The kitchen and downstairs half bath are below the second bath. So maybe the 2" vent is venting both second bath as well as downstairs. The reason i think that is true is because all three old fixtures in master bath (the one I'm renovating) were plumbed to drain into this 3" pipe, as seen below. First connection is for toilet, second for sink (sink has separate vent), and third (bottom of pic) is for old tub. Builder wouldn't have drained toilet into vent stack for downstairs fixtures.

    IMAG1078.jpg
    Last edited: Dec 21, 2013
  18. Caduceus

    Caduceus Master Plumber

    Messages:
    136
    Location:
    Pittsburgh, PA
    It's okay to pipe the shower into the stack. That is the main soil stack and fixtures can drain into it as long as they have their own independent vent. Any fixtures connecting to the stack below should already have their own vents.
    If that 3"x3"x2" wye is the highest connected fixture, then the remainder of the soil stack becomes the stack vent and will also serve as the vent for the 2" shower p-trap. Meaning this...it looks like upstream of the shower the 3" 90 bends vertically and may go through the roof from there. As long as no fixtures flow in from another higher level than the shower.
  19. aharami

    aharami New Member

    Messages:
    21
    Location:
    New Jersey
    Yes, that's right, no other fixture upstream of the shower wye. Thank you for explaining.

    Now the question is: can I take the shower ptrap left to right and then make a u into the 3"main using a 3x3x2 wye? See picture
    IMAG1074.jpg
  20. aharami

    aharami New Member

    Messages:
    21
    Location:
    New Jersey
    Also, I'm assuming I did this incorrectly, right? Since the drain on the left goes down before hitting the vent, it would be considered an s trap. I'd need to take out that 90 degree turn and put in a T, and then connect to the main vent in the attic, right?

    IMAG1051.jpg
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