Easy sink drain question

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by RyanP, Sep 4, 2008.

  1. RyanP

    RyanP New Member

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    I'm sorry for this basic question, but I'd like some insight on this issue. I am installing a new vanity that is open underneath and has a shelf that runs across the bottom probably 6" off the floor. It also came with a basket that sits on that shelf (I guess for towels and whatnot). Unfortunately the drain coming out of the wall is low on the wall, so having a p-trap would interfere with the shelf/basket. Is it allowable to have an elevated p-trap and then a vertical drop to the wall drain? I've tried to diagram it (albeit crudely--I'm no artist)...this is a side view, and on the upper portion, there is a false front, so it's open behind there. Thanks for any help!
    Ryan


    Drain-Diagram.JPG
     
  2. Master Plumber 101

    Master Plumber 101 In the Trades

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    The proper way to do this is to cut open wall and raise tee in wall to the proper height.
     
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  4. RyanP

    RyanP New Member

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    Should a plumber have known that? I had one in while I had the walls down, and he saw the vanity and put in a new drain (and a new T and everything), but for some reason he did not raise the drain. I was pretty fired up when I figured all that out (I know, I should have thought about it before putting the walls back, but I assumed he would set it at the appropriate height to work). I imagine he didn't b/c it would have meant cutting a new hole in the stud, and he didn't want to take the time. That said, I would like to not go back into the wall if I don't have to. Is there a danger of setting it up as shown? Thanks!
    Ryan
     
  5. Redwood

    Redwood Master Plumber

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    Yes the trap would not be properly vented and the water could siphon out of the trap allowing sewer gases to enter your home.
     
  6. Master Plumber 101

    Master Plumber 101 In the Trades

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    You will not have proper drainage. Imagine having a 2 liter pop bottle filled with water, turn it upside down and drain it. You will find that it chugs out rather than a smooth flow. Take that same situation, drain it and poke a hole in top of bottle as it drain's you will see the difference in flow. If you leave it as drawn it will not work properly. I would do it right and move tee to proper height. About 18" above floor should be good.
     
  7. hj

    hj Moderator & Master Plumber Staff Member

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    drains

    Your soda bottle analogy is completely off base. He would create an "S" trap, not a closed system. One feature of an "S" trap or any unvented drain is that it will drain MUCH faster than a vented one. Which is the problem because it will also suck the water out of the trap. The farther down the outlet pipe drops before it encounters a source of air, the better the sink will drain.
     
  8. Master Plumber 101

    Master Plumber 101 In the Trades

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    Are you a plumber or a handyman. My soda bottle theory is a perfect example how a vent system work's. I guess your not smart enough to understand that. Try it maybe you will learn something new.
     
  9. nhmaster

    nhmaster Master Plumber

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    When the sink is full of water and then you pull the plug there will initially be a column of air between the bottom of the sink plug and the water surface of the trap. As the plug is pulled, the air compresses first. Then the water begins to move rapidly through the trap. the rapid movement of water in the trap, along with the compressed air column causes the trap to siphon. Basic trap theory 101. It's even in the commentary in the code book.
     
  10. Master Plumber 101

    Master Plumber 101 In the Trades

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    That explanation is for the homeowner to understand. They are not gonna open up a code book. hj still didn't understand the pop bottle theory.
     
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    And what happens when you poke a hole in the pop bottle, which is what a draining sink is...you don't seem to get it - it's open at both ends.
     
  12. Master Plumber 101

    Master Plumber 101 In the Trades

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    DA! Try draining a sink with no vent, than one with a vent there is a clear difference. The pop bottle represent's the difference in draining between a vent and no vent. People who are not plumber's are not gonna understand the technical explanation for a vent.The explanation of the pop bottle was for this post and the person wanting to know what would happen with out one. You don't get it!
     
  13. nhmaster

    nhmaster Master Plumber

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    Guess I don't get it either. Try explaining it again please. because I have a set up in the classroom that allows me to shutoff the vent, partially open the vent and keep track of either positive or negative pressure at the vent and plugging the vent has virtually no effect on the sinks ability to drain as it gets plenty of air from the sink (which is also one of the ways a trap can siphon. The posters diagram in no way illustrates a closed bottle situation that you are describing.
     
  14. patrick88

    patrick88 Plumber

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    The "S" trap will drain great. The problem is it drains to fast. The water shoots down and pulls the trap dry or almost dry.
    I brushed my teeth in a house that had "S" traps. The stink that came out the drain was not flowers.

    The poster should have his plumber fix the problem.
     
  15. Cookie

    Cookie .

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    You know what Ryan, you should call back that same plumber if you haven't already and get it to fix it to the specs. Get him to fix it so it drains properly for you. If that means he has to do alot of work, in cutting into the wall, the stud, and then whatever, and putting it all back, then, so be it. It is his responsibility. I would not pay him a dime either to do anything extra. It is his job to do it right. If he doesn't come back and fix it, then, Ryan, you take him to court, it costs nearly nothing to do so.



     
  16. Cass

    Cass Plumber

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    If you don't want to open the wall you could put the trap as high as possible and run it into a T inside the cabinet and install an AAV as high as possible above the T then let it drain from there to the wall. That would eliminate the S trap.

    It wouldn't be perfect but it should work OK.

    Opening the wall and raising the T would be the right thing to do.
     
    Last edited: Sep 5, 2008
  17. hj

    hj Moderator & Master Plumber Staff Member

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    Mp101

    The problem with having a battle of wits with "Master" plumber101, is that we are fighting with an unarmed person. He has absolutely no concept or knowledge of how siphons work. I could give him multidinous examples but they would all be beyond his comprehension. I wonder how he would use his soda bottle example to siphon gas out of his car. His soda bottle explains why a water heater will not drain until you introduce air into the tank, but that has nothing to do with sink drain, "S" traps, or anything else in this thread.
     
  18. nhmaster

    nhmaster Master Plumber

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    I have several S and P trap setups in the classroom. All with gauges to monitor vaccuum or pressure. I can run just about any drain scenario imaginable. If 101 would like I can even provide video or the siphon effect to better educate him. I really don't think it's his fault though. When you spend you entire life working in a state with very loose plumbing code you probably won't have a thourough understanding of plumbing principals either. god forbid we get into anything more complicated than this:D
     
  19. Master Plumber 101

    Master Plumber 101 In the Trades

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    The definition of a vent is: to equalize pressure and ventilate the system. I was simply giving my explanation of how the vent equalizes pressure's when a fixture drain's. I question the UPC it seems to be a bit hack.
     
  20. Redwood

    Redwood Master Plumber

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    The main purpose of venting is to equalize pressures and protect the trap seal!
     
  21. hj

    hj Moderator & Master Plumber Staff Member

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    Upc

    It could be "hack" which is why the IPC contractors scuttled the merger agreement when they found out they would have to start doing things properly, and give up some of their pet "easy" methods.
     
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