Please look at my washing machine/utility sink drain setup...need advice.

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Dave88LX, Nov 27, 2011.

  1. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
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    quote;
    And here I thought that each trap required it's own vent...

    Every trap REQUIRES a vent, but the vent can be shared with other traps is that is more convenient. There are MANY ways to revise the drain system so it is "correct", but if you were to purchase the wall mount bracket for that sink so you could elevate it a couple of inches higher, what you have, even though it is "improper", would work, after you unplug the stoppage causing the backup.​
  2. Dave88LX

    Dave88LX Network engineer

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    Location:
    AA Co, MD
    OK I don't mean to stir the pot, but just get a better understanding of things. I have had a couple people tell me that since my drains are within 4' of the waste/vent stack, then I do not need additional ventilation? Looking at my diagram with a "WTF are you doing?" face...

    Also, more for my understanding, what is the reasoning on where you can and can't use SanTee vs. Wye fittings? What is the difference in function? Thank you.
  3. jimbo

    jimbo Plumber

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    8,997
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    San Diego
    It has to do with the sweep and not tending to back waste up into the side inlet. On the vertical, a wye inlet would have the vent below the weir of the trap, and thus the trap would siphon.
  4. mtcummins

    mtcummins In the Trades

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    380
    Location:
    Pittsburgh PA
    Basically, you can't put a Tee fitting on its side, so that you have a 90 degree turn, in a drain line. You also should not use a 90 degree elbow on its side in a drain line. What you want for your sink to be proper is a 45 degree turn into a wye fitting, giving a more gentle turn and better flow rate.

    Vertically, you do not want waste lines going into a wye, as the vent line comes down too far (below the trap weir, as jimbo said), and you end up with an S-trap. This is where you need a SanTee, which keeps the vent line higher than the trap.

    For venting, most of this doesn't apply, but for drain lines, you have to be very cautious which fitting you are using and where.

    As for your vent situation, i'm not sure exactly what the code is, but I think that you're ok with the sink drain being between the standpipe and the vent, with both sharing the vent. If the standpipe was between the sink and the main line, you would probably have very poor venting of the sink while the washer was discharging, and this would be more concerning. If you don't mind raising your sink, you could simply cut out the SanTee and replace it with a wye and 45, put in a proper trap, and call it a day, other than cleaning out whatever clog you have going on. Again, i can't say for sure that this will pass code, but it would be very functional. If you want to get into a much bigger project, you could rip it all out and follow the advice above.

    It looks like you could also just lower your entire assembly (rather than raising the sink) by cutting the vent line above the main drain tie-in, pull the whole drain assembly out, cut the drain part below the cleanout shorter, put it back in, and extend your vent with a chunk of 2" and 2 sleeves. I'd still fix the sink drain with a wye and proper P trap, but this would solve the height problem with minimal work.
  5. Dave88LX

    Dave88LX Network engineer

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    21
    Location:
    AA Co, MD
    Wow, thanks for taking the time to type all that out.

    In the picture above, the sink drain, what is the proper way to come out from the 2" horizontal? A Wye/45 with a cap in the other end? I already purchased a 2" 90 with 1-1/2" adapter for the trap stub-out (I suppose I could have just done 1-1/2" the entire way). Is this going to pose a problem? Probably not optimal, but I don't see it saturating the drain...

    I'll re-read all the rest after supper. :)
  6. Dave88LX

    Dave88LX Network engineer

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    21
    Location:
    AA Co, MD
    Well, that was a hard lesson to find out that vent wasn't entirely 'dry'...up comes 3 rows of flooring + underlayment, and a lot of towels (Translation: Opened up the vent/drain in the basement, used the sink upstairs. Water all over the downstairs.) I tested it a couple days ago, and the drain was definitely coming down the other pipe. Wonder if there is an issue upstairs too. FML. Time for a beer.
  7. Dave88LX

    Dave88LX Network engineer

    Messages:
    21
    Location:
    AA Co, MD
    Alright, got it all done last night, minus the vent line coming out from the sink drain. I had a few people tell me it was so close to the vertical stack that it wasn't necessary.

    But, I screwed up. How badly? I don't know...you can tell me.

    I THOUGHT when I was checking the pipes to see if they were drain/vent or just vent, that it was just a vent. Well, I found out the hard way last night when I washed my hands, that it was in fact the drain from the sink upstairs. What a mess to clean up.

    Here is where I went wrong. When I had the water draining, I felt the 2 pipes, and I felt what felt like water flowing in the other pipe, and felt the vibration etc.; but felt no vibration in this pipe we are working on. Turns out, that vibration I was feeling is because that other ABS pipe was resting on the copper supply line, and transferring vibrations in that way. Once I pushed up on the other ABS pipe, with the water running, I felt nothing in it. So, I don't know what the heck is going on. I will take a couple more pictures and hopefully you can help me understand.

    Based on that information, is my 'vent' completely wrong now?

    Also, even with the sink T above the washer T, when I put the hose in the washer stack, it backs up and then fills up the sink. I must have a good clog below the slab somewhere. My little 25' snake didn't catch anything though. Might need to call someone in for that?
  8. cacher_chick

    cacher_chick Test, Don't Guess!

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    The pipe coming down from the upstairs is a drain, and it cannot be used as a vent.
    You need a new vent if you plan on complying with any plumbing code.

    In addition, the drain pipe itself is likely too small to meet code seeing that there are additional fixtures connected to it.

    Isn't plumbing fun?
    Last edited: Nov 29, 2011
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
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    Location:
    Cave Creek, Arizona
    quote; You also should not use a 90 degree elbow on its side in a drain line.

    Interesting because almost EVERY DWV has a least ONE elbow on its side, and most have SEVERAL. Being "close" to a vent is NOT the definition of whether it is proper or not. Just because your refrigerator is next to the kitchen table will NOT keep it from going sour. In fact, the washer flowing past the sink drain is NOT the ideal configuration, and is FAR from ideal, but as I mentioned previously, it WILL work, but it is NOT how I would do it. The prohibition against a sanitary tee in a horizontal line has to do with the limited "sweep" the branch open has, compared to "Y"s and combos.
  10. Dave88LX

    Dave88LX Network engineer

    Messages:
    21
    Location:
    AA Co, MD
    No, not fun, not fun at all! :) Just so you guys understand I'm not trying to add anything new or fancy here, just trying to properly 'fix' was was done previously. It's also a very slow drain still. Might have to call out one of you pros to do a real job on cleaning out all my drains/traps/pipes whatever.

    I'm going to post a couple pictures to see if you can hopefully help me figure out what I have going on here. Any ideas?


    This is below the bathroom sink upstairs. The drain is obviously the drain, Line B is unknown. There is something protruding up into the attic above this area and 90'd over to the main stack vent and through the roof though.
    [​IMG]



    Same 2 lines. Line labeled 'drain' is what is turning down the wall and is the same pipe that the washer/sink are draining into. Line B goes into the adjacent room.
    [​IMG]



    Line B coming in. Not connected to anything, just runs straight into a soil pipe and down into the concrete slab.
    [​IMG]



    Another shot of the big mess in the adjacent room. I'd like to tuck it up as closely to the joists as possible when I refinish the basement so I don't have to build a huge bulkhead around all that mess.
    [​IMG]
  11. Dave88LX

    Dave88LX Network engineer

    Messages:
    21
    Location:
    AA Co, MD
    Here is what I ended up with. Go easy on me, first time using PVC for something other than a potato gun. :) Still need to put a couple more hangers on it.

    Open to any criticism/opinions.


    [​IMG]
  12. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    HJ, are you referring to long sweep 90s on a horizontal drain line? I'm not sure if my county allows those (we have lots of dumb extra rules), but those I think are fine. I was talking about the tighter elbow, i think usually you guys refer to them as vent elbows. Sorry if I wasn't clear on that, I usually just call that a 90 and the other a long sweep 90.

    I was told by local plumbers that we can't even use the long sweeps on their side in my county. As dumb as it is, we had to do a 45 and a street 45 to make a 90 turn, which is exactly the same thing, but has an extra potential leak point. yeah... dumb.

    Looks like you have quite the mess of a project there now... Def want to get some kind of venting on that, even if you have to just do a couple AAVs (as a last resort). You might have a vent in there somewhere you can use, but its hard to tell (for me at least) from the pictures. The Line B... is there a kitchen sink, shower, tub, anything near there? Could this be a trap vent for a floor drain? Plumbers, can this be used if it is a floor drain vent, or would that overload it?
  13. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    Sorry, was typing while you posted, so didn't see ur last one. I believe this is all correct, other than the whole wet vent thing... what you're using as a vent is in fact not a vent, so its still not done correctly. It will probably work ok, if whatever sink above that drains through that line is vented, but definitely still not up to code. If you were to have laundry draining while using the upstairs sink, you would probably have very little venting supplied to the laundry, and could end up with a siphoned trap.
  14. dlarrivee

    dlarrivee New Member

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    1,172
    Location:
    Canada
    Nice job on what you did there, now we need to work on the vent though.
  15. Hammerlane

    Hammerlane Member

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    252
    Location:
    Ohio
    What if Dave wanted or needed to have both washer standpipe and laundry sink drain on the same branch drain. And assume he had vent only above the stack. Would the following work?
    Last edited: Nov 30, 2011
  16. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,249
    Location:
    Land of Cheese
    That would put the tee for the sink too high. Also, a vent tee is not a drainage fitting and should not be used on it's back.
  17. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    unless i'm missing something, there is no tee being used as a drainage fitting, only as vent tie-ins. the pictures show some of them backwards and such, but I think they're being used correctly for their intended purposes in your drawing. in which case, yes this would work, if you could keep the sink drain low enough.

    am i missing something?
  18. Yersmay

    Yersmay Writing, constructionDIY Member

    Messages:
    62
    Location:
    Los Angeles
    question

    MT,

    I think I understand the logic of why the latest version will work, as you say it will, but I'm curious about your statement that some of the fittings are 'backwards'. For the life of me, I can't spot one that is backwards. For the purposes of ongoing education, can you indicate which? Thanks in advance!
  19. Dave88LX

    Dave88LX Network engineer

    Messages:
    21
    Location:
    AA Co, MD
    OK this is probably a goofy question but I will ask...washing machine supply hoses, how far open do you turn the spigot? All the way? I don't know if it's bad to leave it all the way open.

    Thanks.
  20. Dave88LX

    Dave88LX Network engineer

    Messages:
    21
    Location:
    AA Co, MD
    Top vent SanTee backwards?
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