Double Elbow in Horizontal?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by mhw, Dec 18, 2011.

  1. mhw

    mhw New Member

    Messages:
    4
    Location:
    California
    Hi All,

    I'm a plumbing neophyte having recurring blockages in two upstairs toilets that are connected to the same drain pipe and am wondering what the problem is. The toilets are about 12 feet apart and come together into another horizontal pipe with what I think is called a double elbow. That ABS horizontal pipe is about 3' long and connects to a cast iron vertical with a cast iron 90 degree elbow. Here is a diagram and some pictures:

    diagram.jpg double elbow.jpg from toilet.jpg 90 horiz to vert.jpg

    Could the double elbow be the problem? Also, there seems to be some slope away from the toilets to the elbow, but the 3' section between that and the vertical is fairly flat. We sent a camera down to have a look and saw that when one toilet was flushed, the water ran straight through the elbow towards the other toilet. in other words, there wasn't much if any deflection provided by the elbow. The water sloshed back and forth between the two toilets until it eventually found the elbow and drained out (although there was some standing water.)

    We've never had four blockages in a 9 month period before, and are wondering if it's not us but the design.

    I would greatly appreciate any help and/or advice.

    Thanks,

    Michael
  2. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,072
    Location:
    Maine
    Yea, that's not the correct fitting there. Should have been a double combo or a long sweep ell into the end of a wye fitting.
  3. mhw

    mhw New Member

    Messages:
    4
    Location:
    California
    Thanks for the quick response. I assume this is part of the plumbing code?
    Last edited: Dec 18, 2011
  4. billthebuilder

    billthebuilder New Member

    Messages:
    4
    Location:
    San Diego, CA
    706.3 Horizontal drainage lines connecting with other horizontal drainage lines shall enter through 45 degree (0.79 rad) wye branches, combination wye and one-eighth (1/8) bend branches, or other approved fittings of equivalent sweep.

    agree with TS. all yr fitting's gonna do is send waste from one end of the line to the other end. no real sweep, so everything flows across and solids get stranded - just asking for trouble. standing water means you prob don't have good slope ether. short bend to vertical sholdn't be problem except if the 3 ft section is flat.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,285
    Location:
    Cave Creek, Arizona
    Most codes prohibit "double elbows" for anything other than vent lines. But the crucial question is WHERE does the stoppage occur? If it is in the horizontal sections between the toilets, then the twin ell is the reason, if anywhere else you have a different problem. you show a tub and shower connecting to those lines also. I would be interested in HOW they are connected, and is there a "vent" on the left side also?
    Last edited: Dec 19, 2011
  6. mhw

    mhw New Member

    Messages:
    4
    Location:
    California
    Thanks for weighing in.

    There's no clean out, and the toilets connect to each other with that 12' horizontal line, so attempts to snake it by pulling a toilet have not worked -- the snake just comes up into the other toilet. So, they've had to go up on the roof and snake through a vent (so, at least there's one.) Never pulled anything out, but eventually it just cleared.

    My past attempts to plunge the problem have always led to waste in the tub and shower, so I'm guessing they connect to that horizontal pretty much as drawn. The picture of the toilet shows a (2 1/2" ?) line coming up at a 45, so I'm guessing that's the tub and not a vent as I had originally thought (it's a whirlpool tub, so not so easy for me to decipher from down below.) If that's not the vent, then there's only one vent on the "left" side for the entire run. I supposed there could be one that's hidden on the right side, but that picture showing the toilet is taken from the ell, so you can see everything that I can.

    Several plumbers who were here for the look through the camera thought that the blockages probably occurred somewhere in the long horizontal or just after the twin ell (didn't know what the fitting was until later) in the 3' horizontal which is pretty darned flat. We opened up the ceiling after the camera work; it had appeared through the camera as a tee without any real sweep into the other horizontal line. We almost didn't notice it as the camera just moved across toward the other (left) toilet.

    My guess is that stuff eventually makes it to the ell and stops there or slightly past it (just based on my plunging results.) I don't know how things are configured to the left of the twin ell as we haven't opened up that ceiling yet and the view is blocked by framing. If there's just one vent on that side for the whole run, might that be the problem?

    Thanks in advance.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,285
    Location:
    Cave Creek, Arizona
    WHICH vent do they snake through, where does it go, and where is it in the photos? It could NOT be the one in the drawing because that one would wind up going through the twin ell the same as snaking from a toilet. IF that 2" line on a 45 degree angle is the tub or shower drain then it is COMPLETELY improper. WHO DID THIS INSTALLATION, and did he get it plumbing knowledge from a "Become a Plumber in Two Weeks" book?
  8. mhw

    mhw New Member

    Messages:
    4
    Location:
    California
    "Become a Plumber in Two Weeks" LOL, great. I wish I knew. It happened before we arrived on the scene, no doubt by the same general contractor who screwed stair rail into dry wall instead of bothering to find the studs.

    Re the vent, the short answer is I don't know. I get your point, though. I can only assume it didn't come down through that vent for the reason you state. There must be some other venting, maybe in the part of the short horizontal that we haven't exposed yet. I'm going to have to open up more of the ceiling to see what exactly is going on. Guess I know what I'm doing this weekend...

    I'll post more info as soon as I find out. Thanks, again.
  9. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    Looks like you have a good bit of replumbing to do...

    You definitely need to get rid of the double el, and replace it with a combination wye and long sweep 90, or wye, 45, and long sweep 90. I'm guessing they used that fitting for ease of use, as it was easier to pull it through and go both ways on the other side of the joist, rather than drilling 2 pipes through that joist. Understandable, but problematic, and generally against code.

    While you're doing all that cutting, I'd cut the CI vertical line out, use one of those banded ferncos to convert it to ABS, and put in a new ABS elbow, but lower it a bit to get 1/4" per foot fall on that horizontal line. Now that its all open, worst part will be cutting the CI pipe.

    As far as the drain/vent tie in... Looks like a vent to me based on the way its tied in, proximity to toilet, etc, but it's hard to say. If you were snaking down through the roof through a main stack, there is almost no chance that the snake would come down that particular vent. Only way it would end up there is if that vent goes directly through the roof. If it ties into a main stack, the snake would have to magically do a 90 degree turn into a smaller pipe while going down the stack... just doesn't happen that way.

    Why is there a banded fernco on the other end of that CI line? Is that fitting lose? Seems odd...
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