Will this work for new P-trap for vanity?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by skibumdc, Jan 26, 2009.

  1. skibumdc

    skibumdc New Member

    Messages:
    6
    [​IMG]
    House builder used solvent 90* downturn on 1/2" pipe to threaded connection as shown.

    I was planning to use another 90* elbow, use 1/2" PVC to extend drain out, then use p-trap to turn the drain up towards sink and reduce pipe to 1/4"

    Will this work?

    I have my doubts since the water has to flow upwards now....but it does than in the P-trap anyways.

    If not, I guess my fix to to cut off the solvent downturn and use a new solvent to threaded connection and extend drain out to the P-trap.
  2. Terry

    Terry Administrator Staff Member

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    Location:
    Bothell, Washington
    The purpose of the p-trap is to have a water seal, to prevent sewer gas from entering the home,
    But not so much seal that it prevents scouring of the trap itself.

    What you have is much too deep.
    Expect problems with that.
  3. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    If you take a picture of that, you can post it in Mark's "Pig Slop Plumbing 2009 Contest"
  4. skibumdc

    skibumdc New Member

    Messages:
    6
    New idea

    I didn't know I posted in a comedian forum.

    I brainstormed last night and came up with a better idea.

    What do y'all think?
    [​IMG]
  5. kingsotall

    kingsotall Plunger/TurdPuncher

    Redwood might be right about the pic thing. It's hard to get a judge on distances with the drawings you posted.
  6. skibumdc

    skibumdc New Member

    Messages:
    6
    The horizontal piece to extend to under the new sink will be about 5-6", nothing too big. The drop from the sink to the proposed horizontal piece is approximately 8". Again, nothing dramatic.

    I guess my BIG question is whether the P-trap needs to be directly under the sink or can it be attached to the wall as pictured and plumbing from sink ran to the P-trap as shown>
  7. nhmaster

    nhmaster Master Plumber

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    3,189
    Location:
    S. Maine
    What you have drawn is ok, handicapped laves are often piped back to the wall to keep the pipes out of the way.
  8. gardner

    gardner DIY Senior Member

    Messages:
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    Location:
    Ontario
    non-professional opinion

    How long is the stub sticking out of the wall before the first fitting? I assume this is 1-1/2 PVC, right?

    If you have enough pipe to work with, I think my instinct would be to cut off the first fitting and attach a plain 1-1/4 inch trap adapter. Worst case is you cut away the drywall around the pipe to fit the hub of your new trap adapter and cut the stub off flush with the wall.

    After that you can fit normal trap parts.
  9. skibumdc

    skibumdc New Member

    Messages:
    6
    I have about 1"-1.5" of PVC pipe coming out of the wall.
    So I COULD cut off the old downturn and extend the pipe to directly under the sink.
    I read on another forum may run into problems if I DON'T do this.
    I was just trying to avoid cutting, but I'd rather do it right the first time.
  10. gardner

    gardner DIY Senior Member

    Messages:
    217
    Location:
    Ontario
    I am by no means a professional, but my understanding is that this type of drain stub would normally end in a trap adapter located right at the wall where it can be covered by an escutcheon plate.

    The trap adapter has a slip-fit gasket and hand-nut that allows a standard 1-1/4 chrome or ABS or whatever trap arm to be shoved in and tightened up. The chrome trap arm can be whatever length needed to reach out to where it will meet the trap, all on the (pitched) horizontal from the stub out.

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  11. skibumdc

    skibumdc New Member

    Messages:
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    Problem solved.
    I decided to bite the bullet and cut off the builder 90 downturn.
    Used a solvent joint wall to 1.5" adapter.
    I then ran horizontal pipe to the trap which is now directly underneath the sink.

    I used the flexi extension up to the sink drain.

    Drains perfectly now.

    Thanks for convincing me to do the right thing.
  12. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
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    You think so?

    If we convinced you to do the RIGHT thing, who told you to use the flexi extension? Using that just undid your statement that you "did it the right way".
    [​IMG]
    Last edited by a moderator: Jan 28, 2009
  13. skibumdc

    skibumdc New Member

    Messages:
    6
    Flexi extension no good?
    I should replace it with straight hard PVC?
  14. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    Nope... Yup!
  15. got here too late for your first fix.

    Just to word it all one more time, with a different view, see:
    http://www.terrylove.com/forums/showthread.php?t=15269


    Summary:

    Your first "fix" diagram was a good try; nobody told you to raise the elbow to put it right close to the sink. (This gives you more storage space under the sink too.)

    So, yes, under the sink, you CAN have a tight radius elbow sending the drain over to the wall, or better said, over to a position in space right above the P trap. Next step: right above the P trap, another tight elbow turns the drain down to the P trap (caveats, re: how far that distance is).

    The P trap has to be at the same height as its tailpiece coming out of it (which goes over to the stack). Caveats: 1. Trap weir is the key factor to manage, and 2. The drop from trap weir to the stack is the real thing, which determines the height where you put the trap weir, and 3. tailpiece has to be at least a certain few inches length, number of inches depending on its ID and 4. other caveats etc etc.


    When I first posted about all this, I was confused as until then nobody had ever said specifically that one could turn a drain line with a tight elbow...


    Hope this helps.

    David
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