Is this a "P" or "S" Trap or which is the better alternative?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by dw85745, May 25, 2012.

  1. dw85745

    dw85745 Member

    Messages:
    71
    Location:
    Arizona
    1)

    The shower tailpiece is a straight drop to the "P" trap.
    At the "P" trap exit I can go 90 degrees for about 6 inches, then use a short sweep 90 to drop to the 2 inch drain line.
    FWIW - the vent (wet) is upstream about 15 inches where the shower will connect.

    ==================

    2)
    As a alternative:

    The shower tailpiece is a straight drop to the "P" trap.
    At the "P" trap exit I can insert a street 45 into the 90 degrees (P Trap Exit) fitting
    then run a longer 2 inch line (about 12 inches) to a Y.


    Thanks
    David
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,284
    Location:
    Cave Creek, Arizona
    #1 is a definite No-No!

    We would have to know more about the line you are connecting to in order to say whether #2 is correct or not. How you do it is as important as what you do. My impression is that it would also NOT be a proper connection, given the little you describe about it.
  3. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,237
    Location:
    Land of Cheese
    The key point is that upon leaving the trap, the horizontal pipe cannot exceed 1/4" per foot of pitch before the vertical vent take-off.
  4. dw85745

    dw85745 Member

    Messages:
    71
    Location:
    Arizona
    The existing line is a 2 inch which is "horizontal and hangs from the existing floor joints. (1/4 to 1 slope).
    The existing vent (wet) for the lav is at the end of the the 2 inch line.
    Need to insert a shower drain on the downstream side of where the lav and wet vent are located.

    Normally would go with a San T at the "P" trap exit if a vent was also needed.
    However, no vent needed here.
    So the issue becomes, what's best to use at the "P" trap exit -- or short distance from it --
    so that I get a vertical drop to the existing 2 inch line without creating an "S" trap.


    <<<<<<<< Existing 2 inch <<<<<< Shower <<<<<<<<<<< Lav Wet Vent (ties into the 2 inch with a long sweep 90)

    Agree - However is this case no vertical vent, just a drop (vertical in #!) to the other 2 inch line.


    ///////////////////////////////////
    One other option I could do is use the San T and the run a short piece of 2 inch (like a normal vent pipe) and put a cap on it.
    Would be simplier with a short sweep 90, but not sure whether this creates an S trap with the short piece of 2 inch inserted
    after trap exit ??
    Last edited: May 25, 2012
  5. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,071
    Location:
    Maine
    Untitled.jpg

    ..................................................
  6. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,237
    Location:
    Land of Cheese
    To answer the question headlining your post, S-traps are strictly prohibited in U.S. plumbing codes.
  7. dw85745

    dw85745 Member

    Messages:
    71
    Location:
    Arizona
    Tom Sawyer:

    Don't agree a vent is needed on the vertical since the vent (wet) is upstream and services the lav, the shower and the toilet.

    cacher_chick

    Agree. Hence the basis of my post. That is at what point does one consider going from a "P" trap to an "S".

    For example:
    1) I think we are in agreement that Tom Sawyer's graphic is a "P" trap.
    2) I also think we can agree that if a Ell (90) was put at the "P" trap exit that it would constitute an "S" trap.
    3) So where the debate arises is whether putting a Ell (90) some distance X from the "P" trap exit still makes it an "S" trap or
    can it be considered a "P" trap?
    If a "P" then what is that X distance?
    Last edited: May 26, 2012
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,284
    Location:
    Cave Creek, Arizona
    quote;
    The key point is that upon leaving the trap, the horizontal pipe cannot exceed 1/4" per foot of pitch before the vertical vent take-off.

    NOT true, but the slope cannot be such that the vent connection occurs below the weir fo the trap. There is NO distance that will convert an "S" trap to a "P" trap without adding a vent. IF there is no vent then it is NOT a "P" trap regardless of what YOU call it. You also CANNOT connect it to the "drain line" with a sanitary tee since it is a horizontal line.​
  9. dw85745

    dw85745 Member

    Messages:
    71
    Location:
    Arizona
    HorizDrain.jpg

    Here's a picture. I'm venting the bathroom from the end with a wet vent. FWIW there is also an existing vent downstream from the toilet.
    The fixture arm for the shower is my PROBLEM because of the space available. Since the vent is at the end I do NOT need and cannot work in
    a separate vent for the shower. So this leaves me trying to get a "P" trap in with only six inches left before I am directly over the 3 inch horizontal branch line
    (which is below the sub-floor about 12 inches) . So as I see it I have two options available to connect to the 3 inch line.
    1) Bring the the "P" trap end into a San-Tee which will give me a vertical drop to the 3 inch Y Combo and Cap the top of the 2 inch San-Tee since there is NO VENT.
    2) Bring the "P" trap end into a 45 and then drop to my 3 inch line.

    Personally I don't see the difference in one or two (both make the connection).
    Any feedback on (1) or (2) with advantages / disadvantages explained would be appreciated.
    Any alternative also appreciated.


    ==================================

    Here's a good diagram re: "P" Trap slope issue:
    PTrap-Critical.jpg


    On the above example, I disagree with the maker of the drawing that a San-Tee can NOT be used in a horizontal. From my reading it can be used on the
    horizontal for a VENT PIPE ONLY -- however, it can NOT be used as a drain. So in the top picture, the Y Combo could be a San-Tee since it just services a vent.
    However, if this was a wet vent then it would NOT be acceptable.

    Thanks
    David
    Last edited: May 27, 2012
  10. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,237
    Location:
    Land of Cheese
    We still cannot see what YOU have to work with. From what you are describing, the solution might be to make the connection further downstream instead of so close to the shower drain.

    The drawings above fail under code, as they show a 1-1/2" wet vent, which is not allowed.

    The sanitee on the horizontal is strictly prohibited except on a DRY vent connection to a horizontal vent (above the flood rim of the highest fixture served). A wye or combo is the only proper fitting for a vent take-off on a horizontal drain.
    Last edited: May 27, 2012
  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,284
    Location:
    Cave Creek, Arizona
    Options 1 & 2 BOTH mention a "drop". Without a vent you CANNOT "DROP" the line into the main line, PERIOD! You can run from the trap into a horizontal "Y" in the main line as long as the trap outlet and main line are at the same elevation. I am not sure WHY you posted the "P" trap drawings because they have little bearing on what you are describing. FYI, the toilet's "trap weir" is at the poing INSIDE the toilet where the waterway turns downward, NOT in the closet bend, which is why ALL toilets, (except "blow out" bowls which are a separate category), are "S" traps.
  12. dw85745

    dw85745 Member

    Messages:
    71
    Location:
    Arizona
    First let me THANK All for the feedback and your time.

    Let it be known that NONE of these are my drawings. Just some examples I found to help describe the situation.

    cacher_chick

    FWIW I'm using a 2 inch wet and dry vent and where it shows 1 1/2 I'm also using a 2 inch.

    Will double check SAN-TEE can NOT be used for a dry vent on the horizontal.
    Logically -- to me -- this doesn't make sense since whether you use a Y combo to vent vertically from the horizontal or a SAN-TEE,
    both are only carrying air.

    Add: Look at the bottom Note which supports SAN-TEE use for venting. https://ibcode.com/uploads/Aug_24_Sanitary_Tee.pdf
    The bottom pictures show waste into SAN-TEE and I agree NOT TO CODE.

    ===========================================

    Question:

    Then how are you supposed to make the connection from the shower to the 3 inch line ?
    Some how some where the 2 inch line has to get from the shower drain to the 3 inch branch line
    with a "P" trap in the line.

    Posted to show that with the "P" trap connection to the shower, and that at the "P" trap exit, my only alternatives is some kind of drop to the main (in my case branch) line.
    (similar to FIg B as described in Option #1)

    NOTED. As indicated NOT my drawings.

    ---------------------------

    The floor joists are 3 x 9's. From the bottom of the floor joints to the 3 inch branch line is approx. 10 inches. From the bottom the 3 inch branch line to the concrete
    crawl space floor is approx 6 inches. The 3 inch line runs perpendicular to the floor joints.

    So as you see I have approx 19 inch crawl space under the joints in which to work. On top of that, this was a solar home that had river rock originally as the crawl
    space floor which was flooded with self leveling concrete to fill the voids in the rock to keep the rattlesnakes out. The concrete is NOT level, but has rock BUMPS throughout
    on which I have to crawl over or lay on to work. NOTE: This has nothing to do with the plumbing issue other than the difficulty of the working conditions.
    Last edited: May 27, 2012
  13. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,071
    Location:
    Maine
    See post #5

    Cacher, Under the IPC we can now wet vent not one but two bath groups with a single 1 1/2" wet vent.....woooopee

    Here's the rule for venting be it wet, circuit, individual or stack. Anytime crap goes down air goes up. Again see post #5
  14. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,237
    Location:
    Land of Cheese
    I hate to think that you are right about that, but I don't doubt that you are.
    I don't fall under the IPC, so am not completely in the know.


    If the OP would show us some decent pictures of what he has, I'm sure there is a solution.

    The trap can be turned to give you a little more room. The trap can be lowered so that the trap arm is properly pitched to a wye facing out the side of the main line. Again, without seeing it, all we can do is speculate.
    Last edited: May 27, 2012
  15. dw85745

    dw85745 Member

    Messages:
    71
    Location:
    Arizona
    cacher_chick:

    As the original OP there is nothing to show other that the floor joists and a concrete floor. Guess I could show the 3 and then the 2 inch line sloping upward to where the shower will connect.
    I'll try an post a picture or two.

    ===================

    Regarding using of a Y combo, a sanitary tee, and capping the top of the sanitary T since NO vent (as part of the fixture arm).

    In re-reading IPC 704.5, I believe it would be considered a "dead end" and therefore would be prohibited. This makes sense in that gas
    could rise and get trapped in this area.

    So guess my only alternative is go with a 90 to tie into the Y combo or a Y with a 45 which ties in further down the line.

    =====================

    Referencing Tom Sawyer's post #5 -- my plan is to just put a long sweep 2 inch 90 where the sanitary T is shown and tie that into a Y combo that is sitting vertical.
    This way I can get my "P" trap in and a 1/4 to 1 slope prior to making the 90 degree bend downward. Don't personally like the short distance from the P trap exit to where
    the 90 makes it down turn.

    Trying to go flat, then using a 45 to tie into a Y further down the line may pose a problem (will double check)

    >>> Feedback appreciated re use of 90.
    Last edited: May 28, 2012
  16. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,071
    Location:
    Maine
    Absolutely PROHIBITED!

    Untitleduvt.jpg

    Attached Files:

    Last edited: May 28, 2012
  17. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,237
    Location:
    Land of Cheese
    You cannot have a 90 or a tee turning downward unless there is a vent prior to that point. You can use a 90 or 45 on it's side to move the connection further downstream.

    The trap should be low enough for the drain to be piped below the joists. As long as a vent is provided within the maximum allowed distance under your code, the main line connection can be made anywhere beyond that.
    Last edited: May 28, 2012
  18. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,284
    Location:
    Cave Creek, Arizona
    quote; I hate to think that you are right about that

    The IPC is an "opportunist code". If someone wants to do something, usually all he has to do is ask and the code will be revised. As one columnist stated, "The IPC has more ways to 'wet vent' than any other code". As far as the original question is concerned, you can restate the situation as many ways as you want to, but we WILL NEVER tell you it is okay to "drop" into the main line without installing a vent first.
    Last edited: May 28, 2012
  19. dw85745

    dw85745 Member

    Messages:
    71
    Location:
    Arizona
    OK. Will abandon the 90 degree turn idea.
    Still don't get why the shower drain with the 90 is NOT considered vented, since the vent (wet) upstream on the branch line from the lav is within about 1 foot from the shower Y combo rising vertically to tie into the shower fixture arm?

    Add: Here's an example of a 90 degree drop (see picture on page 9) http://www.oboa.on.ca/events/2011/sessions/files/211.pdf
    Any comment appreciated.

    ==========================


    So, general consensus is that if I can go with a Y (rotated upward at 45 degrees and a 45 attached to the P trap exit pipe rotated downward at 45, "I think" I can make the connection further downstream.
    Anyone see any problems with this (assume Tom Sawyer YES picture has the Y rotated Up on on the horizontal)?

    Again thanks all for their time and effort on my behalf.


    =================================

    Re Venting (For my edification can someone please explain why the 90 is not acceptable based on the below venting requirements it would be appreciated):

    909.1 Wet vent permitted.

    Any combination of fixtures within two bathroom groups located on the same floor level are permitted to be vented by a wet vent. The wet vent shall be considered the vent for the fixtures and shall extend from the connection of the dry vent along the direction of the flow in the drain pipe to the most downstream fixture drain connection to the horizontal branch drain. Only the fixtures within the bathroom groups shall connect to the wet–vented horizontal branch drain. Any additional fixtures shall discharge downstream of the wet vent.

    911.1 Circuit vent permitted.

    A maximum of eight fixtures connected to a horizontal branch drain shall be permitted to be circuit vented. Each fixture drain shall connect horizontally to the horizontal branch being circuit vented. The horizontal branch drain shall be classified as a vent from the most downstream fixture drain connection to the most upstream fixture drain connection to the horizontal branch.
    Last edited: May 28, 2012
  20. Terry

    Terry Administrator Staff Member

    Messages:
    14,792
    Location:
    Bothell, Washington
    You are looking at the pictures wrong.
    That is a horizontal wye and a 45
    You can also look at it, and think it's a 90 bend about six inches higher then the main line, but it's not!

    Rotating the wye up to a 45 doesn't work either, unless it's vented above the 45. You can't vent below the trap, which is what happens when you roll the fitting.
    You can roll a fitting and vent the "highest" part. Not the lowest part.
Similar Threads: Trap better
Forum Title Date
Plumbing Forum, Professional & DIY Advice, Tips & Trap/drain on disposer Jul 9, 2014
Plumbing Forum, Professional & DIY Advice, Tips & Strange contraption: Toilet flapper built into middle of overflow tube Jun 11, 2014
Plumbing Forum, Professional & DIY Advice, Tips & 'Nuther S-Trap Dilemma Jun 9, 2014
Plumbing Forum, Professional & DIY Advice, Tips & Straps for PVC DWV Jun 5, 2014
Plumbing Forum, Professional & DIY Advice, Tips & Residential trap primer question Jun 5, 2014

Share This Page