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Thread: Looking for advice on venting

  1. #1

    Default Looking for advice on venting

    Below are some pictures (and a video) of my current basement plumbing. Not being a plumber, I don't know the proper venting or requirements. I'm looking for your help to lead me in the right direction. I can do the work.

    The current stack goes like this, from the floor up:

    It's 4" coming out of the floor.
    Next up is a 4" cleanout tee.
    At the top of the cleanout tee, it drops down to 3".
    A couple of elbows and it makes its way to 3 tees. 1st is a toilet drain, 2nd is vent stack, and 3rd is another toilet drain.

    My plan is to put a washer standpipe in and replace the concrete washtub (which currently drains to a different drain) with a plastic one. The new washtub will drain into this stack on the left.

    Here's what I'd like to do:
    - 4" coming out of the floor as it is.

    - 4" x 4" x 2" hub sanitary tee (with the 2" pointing back towards the wall) with a trap and standpipe for the washer.

    - Directly on top of the first santee, I would put a 4x4x4x2 (right side inlet santee). The 2" would point to the right and become the drain from the washtub (with a trap).

    At this point, my plans don't include any venting or any other changes to accomodate venting.

    Am I ok? Is any venting necessary other than, in theory, utilizing the 3" main stack from above? There isn't any venting on the washtub as it is and it's working fine. I guess it's tied into a different stack though so it's not a good comparison.

    I doubt it's possible that somebody would be flushing both toilets, washer draining, and washtub draining to completely fill the pipe.





    Here's a link to a video I shot of the plumbing just for reference.

    http://www.youtube.com/watch?v=UagbfLO_R-o

  2. #2
    One who lurks Basement_Lurker's Avatar
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    Wow I applaud your thoroughness in presenting your question and details surround it. If you do what you propose, you will be "wet venting" the washer standpipe and the wash basin. Every time someone flushes a toilet upstairs, you risk siphoning the traps down below. And besides, it is usually code to not have anything downstream of a toilet. Of course you'll have to check your local codes for venting requirements as well as allowable fixture units for a 3" stack, but I would have to say that the job is not as quick and easy as you think it is.


    I hope you replace that washtub with something nicer...that thing is a beast!

  3. #3

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    Ok, I don't know any codes but I'll agree with the idea of not putting any other plumbing downstream of a crapper.

    Here's my new idea, tell me what you think.

    Leave the vertical stack on the left alone as it's got the toilet drains plumbed into it.

    Moving over to the right vertical stack, we make some mods. The plumbing will all run along the wall from the left over to it. I would also like to use AAV's to avoid the venting issues.

    1) The washer needs a standpipe. Fasten one to the wall, go in/out of a trap, and start heading towards the right with it.

    2) The horizontal pipe would then meet up with a wye. The other inlet of the wye would come from the new washtub drain which would include a trap.

    3) Immediately after the wye, install an AAV on a santee.

    4) After AAV it would run into a new 4x4x2 tee which would be facing the wall.

    5) On top of the first tee, would be another double tee. Front would be for a cleanout plug, and rear would be for a small standpipe, AAV, and trap for a softener drain.

    Does this plan sound better and correct?

    I'll attach a sketch in a bit here.
    Last edited by mckeand13; 08-21-2007 at 09:39 PM.

  4. #4

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    A quick Photoshop job for a visual. A single basin washtub is going in place of the double. Imagine this one missing half.


  5. #5

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    Just wondering if nobody has any suggestions, or if nobody wants to commit to any advice?

  6. #6
    Forum Admin, Expert Plumber Terry's Avatar
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    The 2" plastic pipe above the laundry tray drain is a vent?
    Why not tie all vents into that at 42" above the floor.

    Each p-trap downstairs should come off separately, and vent separately, and then tie together at 42"

    The toilet waste and vent, is just wierd.

  7. #7
    Retired Defense Industry Engineer jadnashua's Avatar
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    The AAV's won't work properly where you have them...they need to be ideally, above the flood rim of the sink. Under a counter, they would be as high as you could get them and still remove them when they failed.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  8. #8

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    Quote Originally Posted by Terry
    The 2" plastic pipe above the laundry tray drain is a vent?
    Why not tie all vents into that at 42" above the floor.

    No, the 2" you see coming down vertically on the right side of the washtub is a drain from the kitchen and also a shower that was recently added by the previous owner. The kitchen has it's own dedicated vent (if I remember correctly from the last trip to the attic), and the shower has an AAV. This must comply with code as it passed city inspection just before we bought it.

    Each p-trap downstairs should come off separately, and vent separately, and then tie together at 42"

    The toilet waste and vent, is just wierd.

    All of the plumbing on the left side of the washtub is original to the house. It must have met code, at least in '58 when the house was built.
    Does that explain anything further?

  9. #9

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    Let's completely abandon my ideas for the minute.

    I'd like to ask "how would a licensed plumber, doing it correctly, do this job"

    Is that possible to answer without standing in my basement and looking at it?


  10. #10

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    I'll ask one more question. Hopefully. I just want a plan and to get this project taken care of.

    I know "wet venting" isn't the preferred way to do things, but is it ok to do so ?

    Looking at my colorful drawing above, would it make sense to bring a vent up from the washer standpipe, the new washtub, and the softener drain standpipe and tie all of them together and into the pvc on the right side of the existing tub?

    Note: The 2" pvc on the right side of the tub is the drain from a show (with AAV) and the kitchen sink (which has it's own true vent).

    Thanks.

  11. #11
    Commercial Plumber markts30's Avatar
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    I would replace the 4X1 1/2" tapped tee with a 4X2 santee (PVC) attaching it with a transition coupling.
    Above that I would re-build the stack with PVC and a new cleanout (PVC) and, above the new cleanout (about 42" to center) insert an inverted santee...
    Then I would make a new lateral out of PVC with one combo to pick up the laundry sink and a sweep on the end to pick up the stand pipe for the washer...
    Above the combo, use a santee for the PTrap of the tub and do the same for the standpipe for the washer...
    Re-vent the 2 together and tie back into the santee you have inserted into the newly re-built vent stack.

  12. #12

    Default

    Thanks for the reply markts30.

    I think we are on the same page.

    Does the drawing below look like what you are suggesting? I guess I didn't draw every component and maybe not perfectly routed, but the idea seems right?

    The washer, washtub, and softener each gets it own trap and a vent. All of the vents are tied together and back into the stack.


  13. #13

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    Quote Originally Posted by markts30
    I would replace the 4X1 1/2" tapped tee with a 4X2 santee (PVC) attaching it with a transition coupling.
    Above that I would re-build the stack with PVC and a new cleanout (PVC) and, above the new cleanout (about 42" to center) insert an inverted santee...
    Then I would make a new lateral out of PVC with one combo to pick up the laundry sink and a sweep on the end to pick up the stand pipe for the washer...
    Above the combo, use a santee for the PTrap of the tub and do the same for the standpipe for the washer...
    Re-vent the 2 together and tie back into the santee you have inserted into the newly re-built vent stack.
    Could you explain what you mean by combo?

    Do both the washer standpipe and the washtub drain need their own trap? Or could each one just have an elbow and then lead into one trap?

  14. #14
    Forum Admin, Expert Plumber Terry's Avatar
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    They need their own trap and vents.
    And the vents tie together above the flood level, say at 42" off the floor.

  15. #15

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    Quote Originally Posted by Terry
    They need their own trap and vents.
    And the vents tie together above the flood level, say at 42" off the floor.
    Could you explain "flood level"?

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