Crown-Vented Laundry Drain Trap?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by inspectordan, Sep 22, 2012.

  1. inspectordan

    inspectordan New Member

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    Hi All....great forum! I hope I'm not embarrassing myself by asking but does this laundry drain constitute an improper crown-vented trap or any other defective drain/trap? Thanks!
     

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  2. cwhyu2

    cwhyu2 Consultant

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    Yes the stand pipe must not have any off sets.
     
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  4. hj

    hj Moderator & Master Plumber Staff Member

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    NO. It is done like that anytime there is not room in the stud space for the trap and wall box to fit with a straight riser. How else COULD you do it? A box with the outlet offset to the side would help, but they are not that easy to locate. Don't sweat it.
     
  5. Tom Sawyer

    Tom Sawyer In the Trades

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    You need twice the pipe diameter between the trap elbow and the sanitary tee inlet.
     
  6. hj

    hj Moderator & Master Plumber Staff Member

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    I would say he has about that much center to center, and I have never had an inspector turn down an installation like this one. What do you want him to do, remodel the wall to give more room between the brick and the stud?
     
  7. Winslow

    Winslow Plumber

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    The measurement is taken from the crown weir to the opening in the tee. In that situation the inspector is likely to overlook it.
     
  8. Tom Sawyer

    Tom Sawyer In the Trades

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    It's an S trap. Every inspector in a 200 mile radius of here would make him change it. You do what needs to be done to meet code.
     
  9. Winslow

    Winslow Plumber

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    Actually he could remove/relocate that stud on the left side to give him the required 2x trap arm required. The offset in the riser is OK as long as the p-trap is set level.
     
  10. jimbo

    jimbo Plumber

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    The "2x diameter" rule does not mean you need 4 inches between the hubs of the fittings. And I may be a little dizzy on chemo, but I don't really see where this is an S-trap.
     
  11. Tom Sawyer

    Tom Sawyer In the Trades

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    CrownVent.jpg

    You need 2 x the pipe diameter between the weir of the trap and the inlet of the tee. What is there ain't even close. It's an S trap with a vent that does nothing to break the siphon. That trap will siphon.
     
  12. hj

    hj Moderator & Master Plumber Staff Member

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    quote; It's an S trap

    That is the most ridiculous statement ever posted here. There is nothing that even approximates an "S" trap in the installation, and it is EXACTLY like thousands, probably tens of thousands, of washer drain installations, with or without the offset in the riser.
     
  13. Tom Sawyer

    Tom Sawyer In the Trades

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    You need to get the code book out and do some reading. I do agree though that there are thousands of them out there just like that and every one of them is ........wrong. How can yo look at that and not see an S trap? If it's because of the vent then again, read the code book.
     
  14. Winslow

    Winslow Plumber

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    I already said it means from the crown weir of the trap to the opening in the san tee. The hubs have nothing to do with it. The same requirement applies to hubless pipe and fittings.
     
  15. Tom Sawyer

    Tom Sawyer In the Trades

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    CrownVent.jpg ..........................................
     
  16. hj

    hj Moderator & Master Plumber Staff Member

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    That is really stretching things to make it an "S" trap. Using that logic, EVERY "P" trap would be an "S" trap if you turn it on its side. You obviously do NOT know the dynamics of a siphon, which a "TRUE S TRAP" uses to be illegal, nor how a vent works. But then, when you turn a P trap on its side, like your drawing, then there is NO trap at all in the drain. Time for you do some remedial classwork, by taking Plumbing 099.
     
    Last edited: Sep 23, 2012
  17. Tom Sawyer

    Tom Sawyer In the Trades

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    I turned the photo on it's side so that you could more clearly see the S configuration there. The 2x the pipe diameter from the weir to the inlet is what makes a P trap a P trap. Where the trap vents from is incidental. That trap in that configuration will siphon just fine with or without that vent. I have set that exact same thing up in the lab many many times using clear 2" PVC and fittings. given enough velocity (which a washer has) it siphons every time. Increase the weir to inlet by 2x pipe diameter or more and it never siphons. I can't think of a single plumbing code that will allow that configuration and again, there's not a plumbing inspector either state or local that would let that go around here including me.
     
  18. hj

    hj Moderator & Master Plumber Staff Member

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    Thou dost protest too much. You are trying to justify the unjustifyible. You could not make that trap siphon even if you put a suction pump on the bottom of the drain riser. And that is how we tested traps and vents at the Chicago Cabrini Street Testing Laboratory. We did not just depend on gravity to create enough suction. And there are tens of thousands washer drains installed just like that and NONE fo them have "siphon problems", nor could they have them.
     
  19. robert mcalister

    robert mcalister New Member

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    Hi guys, I think I have issues with odor and standpipe backups resulting from an installation just like this. At first I thought I had a clog; however, I think my drain pipe is being overwhelmed depending on how much water my laundry machine decides to use. Please see the attached picture.

    My house was built in 2014 and I just about ripped open my wall and decided to research this a little bit. I had taken pictures before they closed up the wall and found this gem.

    I have emailed my builder and the chief city inspector and I'm curious to see where my "hey is something wrong here?" goes. Either way, based on my reading, it was allowed to be installed against code and it is causing me actual issues.

    So to the naysayers that say "doesn't matter, there's a vent there it is all good" I tend to disagree from actual experience as a pissed homeowner that thinks I have a faulty installation and can't trust licensed plumbers or city inspectors to do their jobs.
     

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  20. standardairconditioner

    standardairconditioner HVAC'ker

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    What makes you think what you have is improper? I see a straight stand pipe, and p-trap, and then a San-Tee after it.

    You understanding of an S-trap is incorrect, and is not what you have here. And do not go with the rest of the pics in this old thread too, they are also incorrect.

    You need to accept you have a clog somewhere down there after the San-Tee. Plastic is all soft to cut and cheap to replace, you may want to remove a section of that vertical to get a Wye and cleanout in there, and mended back with a rubber coupler.
     
    Last edited: Apr 10, 2016
  21. robert mcalister

    robert mcalister New Member

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    Simply because it doesn't have a minimum of two pipe diameters as required by code. There is a reason it is required. And I think I am finding out why, the hard way.

    What you don't see is a P-trap, because there is not a legitimate trap pipe apparently. I'm not an expert, and maybe I have a clog in my less than two year old 3" plumbing I just snaked, but it is a PITA to rip out everything, tear out drywall and repair.
     
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