S-Trap Workaround

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by zinc65man, Feb 14, 2009.

  1. zinc65man

    zinc65man New Member

    Messages:
    5
    Location:
    Ontario
    Hi Everyone,
    Looking for a little advice. I have a vanity that has a "drawer" under the sink (see attached pic) so I'm unable to install a proper P-trap. That leaves me with the dreaded S-trap. But after searching this and other forums, I haven't been able to find an adequate answer to my issue. It looks like most S-trap issues are unvented, or otherwise attach to vertical drains. In my case, I have a vent only 4 inches away from the end of the "S". I just don't see a siphon happening. At the same time, I could envision possible gurgling. So here's the question, is this a rare instance where a S-trap is acceptable?

    As I see it, I have 4 options.

    a) Install the S-pipe as shown in the diagram.

    b) Raise the T joint about 5 inches and install a proper P-trap

    c) Cut the vanity and install a proper P-trap.

    d) Increase the horizontal distance between the trap and the other half of the "S" thereby converting it to a legitimate P-Trap. I've heard that I need at least 2 times the pipe width. If I have 1.5 inch ABS, would that mean a horizontal run of 3 inches? I think this would fit.


    My instinct tells me that the best ways to deal with this (in order) are b, c, and d. I'm hoping that no one finds an issue with a) but it's probably unlikely.

    Really appreciate any commentary.
    Thanks,
    Mike

    Attached Files:

  2. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Raise the tee.
  3. zinc65man

    zinc65man New Member

    Messages:
    5
    Location:
    Ontario
    Well, by that short answer, I'm assume that a) the S-Trap is out. I figured as much. Let's further assume that to move the tee I'm dealing with cast iron and replacing tile that just can't be found or replaced. So I'd rather not do b) either.

    If I implement the d) solution, it'll probably pass code, but will there be gurlging? (In which case, this is not a viable solution for me). Is there any plumber out there that can tell me that "yes, that is legal (barely) and that should work correctly"?
  4. zinc65man

    zinc65man New Member

    Messages:
    5
    Location:
    Ontario
    Also, a quick image of what I mean by the d) solution. A P trap where the "run" is equal to twice the width of the pipe width. So, 3 inch run for 1.5 inch ABS. It's not clear whether this should be twice the width of the pipe or twice the width of the entire trap diameter (around 8 or 9 inches) using 1.5 inch ABS.

    Attached Files:

  5. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    Thats still an S-Trap
  6. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    solution D will never pass code either. No matter what you do you need a P trap configuration there.
  7. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    As long as you have a drop before the vent, you have siphon potential, and it will be ruled an S trap
  8. zinc65man

    zinc65man New Member

    Messages:
    5
    Location:
    Ontario
    Hi everyone,
    This morning I knocked out the drawer in the base of the vanity (which surprisingly also gives me more room to store stuff) and installed a correct P-trap. Thanks to those for addressing my specific vented S-trap question.

    I guess I knew what I was supposed to do all along. I read in one of my books (Do it Yourself, Casell, Parham And Eakes, 2007) that there was no problem with an S-Trap. Also, I read here

    http://www.homerepairforum.com/forum/plumbing/3428-s-traps-o-k.html

    about the "conversion" (with picture). The reason I decided to install a standard P-Trap was that about 90% of articles I read said to just avoid S-Traps, and 10% said that there was no problem. I'm one of those guys that always wants to know why? So in this case, why are these 10% of plumbers saying that it is ok? They seem to have "decades of experience" as well.

    Please remember that I've already installed a P-trap, so I'm on your side.
    I'm just curious as to an ambiguity in the code about run or something like that.

    Mike
  9. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    10% are just plain wrong or uneducated I suppose.
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,235
    Location:
    Cave Creek, Arizona
    wrong

    That is because those 10% are either not plumbers or they are construction plumbers who NEVER have to work with traps. All they have to do is install pipes the way the blueprints show them and they will never create a need for "S" traps.
  11. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    10% of plumbers are lazy.
    10% of plumbers don't know the codes
    10% of plumbers are in their 90's (when they worked in the trade in 1950's, S-traps were allowed)
  12. zinc65man

    zinc65man New Member

    Messages:
    5
    Location:
    Ontario
    I think I get the message :), thanks for all the help and opinions.
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,235
    Location:
    Cave Creek, Arizona
    Not really

    10% of plumbers are in their 90's (when they worked in the trade in 1950's, S-traps were allowed)

    1. I am not 90, yet.
    2. I worked in the trades in the 50's.
    3. "S" traps were NOT allowed then and had not been for many decades. Even "crown vents" which were an upgrade to true "S" traps had been outlawed by the 50's.
    4. Your historical knowledge needs upgrading.
    5. I went to the site that posted that "revising an S trap into a P trap" diagram and explained that anyone who did that must have been fired from Home Depot, and received a somewhat nasty reply that ALL their experts are professionals and I should butt out.
    [​IMG]
  14. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    HJ, that site, ... wow. We could have some fun there. I think it was redwood that posted a link to an old 1910 code book that showed S-traps and my 1917 Ohio plumbing code book only prohibits mechanical traps and traps that have partitions. Also it goes into the allowed material a trap can be made of. I do love the old code books.
  15. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    That particular forum is "controlled" principally by two people, both the plumbing and electrical areas, and they get a little touchy when anyone tries to horn in.
  16. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    This one....
    Google Books Standard Practical Plumbing By R. M. Starbuck 1910

    I almost clicked to join but then again I figured I was on enough Forums already...

    Sewerratz since you already joined why don't you go back and discuss venting with them...

    At least offer this "Hack" solution as better than what they show....

    [​IMG]
  17. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    If that "LazyPup is who I think it is...he's an arrogant know-it-all who is often wrong. I'll have to check out that forum and see if I know of any of their other experts. :rolleyes:
  18. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    don't need it............... don't want it...........
  19. kingsotall

    kingsotall Plunger/TurdPuncher

    hj, red and ratz,
    you guya make me laugh :p Did you guys hold hands when venturing into that other forum or did you guys bum rush 'em like gangbusters¿ :D
  20. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    Looks like Redwood bumrushed them. I was to busy laughing my a$$ off reading some of them posts.
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