Check this Y before I glue it

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Layne, Sep 22, 2011.

  1. Layne

    Layne New Member

    Messages:
    16
    Location:
    Bryan, Texas
    Hello all,
    I'm replacing an old lead bathtub trap and adding a washing machine drain at the same time here. My concern is to make sure I'm doing the Y correctly to prevent washing machine water from backing up into the tub. Specifically, would it be better if the tub Y'd in from the top rather than from the side? The tub is the 1.5" trap, the washer is the 2" pipe facing the camera. The center of the horizontal pipes is 7" below the floor. I don't think it matters, but the washer drain has 3 elbows and a trap before entering the photographed area.

    Bonus question: The rubber hub donut is not very tight. Previous ones I've used had to be soaped up and driven in. This one just pressed in by hand. Should I put some kind of sealer on it?

    [​IMG]
  2. nukeman

    nukeman Nuclear Engineer

    Messages:
    711
    Location:
    VA
    You need to get some vents in there. One for the tub, another for the washer. You may have already planned the vent for the washer (and we can't see it), but the way it is, the washer will likely pull the water out of the tub trap when it discharges.
  3. Layne

    Layne New Member

    Messages:
    16
    Location:
    Bryan, Texas
    The vent is directly above the old cast iron pipe. I was of the impression that this was adequate to vent both items, but I do see what you're saying with the velocity of the washer possibly creating a suction. I could go from just to the right of the tub trap up the wall and tie into the existing vent. It won't be easy since it's galvanized steel up there, but it beats going through the roof. There is no vent for the washer out of view. I can't see the need for one being as there's one at the cast iron like I said, but maybe I'm missing something.
  4. nukeman

    nukeman Nuclear Engineer

    Messages:
    711
    Location:
    VA
    Every trap needs a vent in order to protect the trap seal. Also, the CI pipe might not really be a vent. If there is something draining from an upper level, it is not considered a vent. Sure, it may have worked like one, but a plumbing inspector would not approve it as a vent now (if being used as a drain). Even if the CI was a true vent, it would be fine if only the tub was connected like that, but since the washer is also tied in, there needs to be a vent between the tub trap and where it connects to the washer drain. An inspector will want to see a vent for the washer as well. If the CI pipe is a true vent and within distance, it may work without another vent on the washer, but I think your distances are too great.

    For 2" pipe, you typically need the vent within 5' to 8' (depending on your code) from the trap. Another challenge with vents is they can't go horizontal until at least 6" above the flood rim of the highest fixture served (or sometimes 42", whichever is larger). This can make some of the underfloor connections tricky (tub, shower, etc.).

    BTW: Typically code calls for the washer trap to be above the floor (in a wall) and there are limitations (min and max) on how tall the washer standpipe can be.

    I'm not a plumber, but I've been through all this stuff in detail with my reno. :)
    Last edited: Sep 22, 2011
  5. Layne

    Layne New Member

    Messages:
    16
    Location:
    Bryan, Texas
    Hmm, very interesting stuff. The CI is a true vent, there is no upper level. It changes to a galvanized pipe and turns horizontal just above the toilet tank, then ties in to the 6" CI vent going out the roof. The washer hookup is just barely past the foot of the tub, so about 6ft away from the CI pipe. I'm interested in why the washer trap would need to be in a wall, as I've already planned to place it under the floor. There won't be an inspection, but obviously I want it to work well anyway.
  6. nukeman

    nukeman Nuclear Engineer

    Messages:
    711
    Location:
    VA
    The washer trap is usually raised as there is a limit on how long the standpipe can be. Around here, it has to be between 18" and 42". If you put the trap below the floor, you will exceed the 42" mark.

    Terry has some nice pics on here on what the washer setup should look like. I'll see if I can find it for ya.

    You probably have different code in Tx, but this might help to guide you:

    https://www2.iccsafe.org/states/Virginia/Plumbing/Plumbing_Frameset.html

    See sections 406 and 802.4. Chapter 9 will give you some info on the vents.

    EDIT: Here it is...

    http://www.terrylove.com/forums/attachment.php?attachmentid=12678&d=1301504620
    Last edited: Sep 22, 2011
  7. mrmedic

    mrmedic Junior Member

    Messages:
    57
    Location:
    Delaware
    Here is another washer stand pipe drawing

    laundry standpipe.jpg
  8. Terry

    Terry Administrator Staff Member

    Messages:
    15,416
    Location:
    Bothell, Washington
    The washer needs to come in "below" the tub drain.
    Cut a fitting in below the tee, run over for the washer, extend through the floor and trap it at about 12" from the floor, vent it and either go through the roof at that point or revent in the ceiling to the existing vent that the tub uses.

    If you run the washer past the tub, is will suck the trap dry.
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    The cast iron pipe WAS a vent at one time, but now that you have changed the piping it is useless as a vent, and could be eliminated if it were necessary. Falling water has "inertia" and if it falls far enough, its inertia can carry it right through the trap without stopping to keep the trap full of water.
  10. Layne

    Layne New Member

    Messages:
    16
    Location:
    Bryan, Texas
    Where exactly are we talking about here? The cast iron below where the tub goes in? That space is already occupied by the kitchen sink drain coming from the other direction (barely visable in the picture).

    As I understand the VA code linked above, the washer vent needs to be within 8ft of the standpipe, which it is so long as I don't mess it up by adding the tub drain. What I think I'm hearing here is that splicing in the tub prior to the vent makes the washer setup no good? So even if I add a seperate vent for the tub, it doesn't fix the washer. So I either need to add 2 new vents, or bring one of the items in somewhere else so it doesn't interfere with the existing vent?
  11. nukeman

    nukeman Nuclear Engineer

    Messages:
    711
    Location:
    VA
    It can be a bit tricky to satify all of the code requirements. This is why plumbers have to study and do on-the-job training for this work. Often, you meet one requirement and you mess up another in the process.

    You see, if you had just the washer, you might be okay in VA in terms of distance to vent. However, that distance is based on 1/4" drop per ft. If you were to drop more, then you would have to shorten the distance. Many parts of the west use UPC code, which is 5'-6' for 2" pipe, I believe. Now let's say you keep the trap under the floor. What hj is saying is that the falling water (if falls far enough) can carry the water right out of the trap. So then you say, "I'll just raise the trap up and use an elbow to get it going back down under the floor". That won't work either as it forms an S-trap. To get the washer "right" you really need to do like in Terry's pic with the raised trap, a santee (with vent going up), and then go under the floor. After all that, you still need to figure out venting the tub.

    The codes don't really tell you *how* to do it, but they do tell you *what* requirements your design has to meet. The only easy way to figure it out is with education + experience. Without the experience, you have to spend a lot of extra time drawing things out and checking them against the code to make sure they will work. For me, I spent the time to educate myself to do it right. If I was in a hurry, I would have hired a plumber as their experience saves a ton of time. It really does take a lot of time to figure it all out (even for an engineer) as there are many requirements to try to meet and any one of them that you miss could mean tearing it out and starting over. I know you aren't getting it inspected, but if you treat it like it was, you'll be happier in the end as you know it will work correctly and you'll feel good that it is "right".
  12. Terry

    Terry Administrator Staff Member

    Messages:
    15,416
    Location:
    Bothell, Washington
    You can't combine the tub and the washer on the same line without two individual vents.
    The traps need be vented before they combine.
    If that means you go farther back, then that is what you do. More pipe will need to be worked on and replaced if you plan on "adding" more to the job.
    You can paste a nose on a nose and call that a pretty face.
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    Unfortunately, we cannot really tell WHAT you are going to do based on your description. The washer trap should NOT be under the floor, for several reasons, and if it is NOT under the floor it DOES require a separate vent. The tub CANNOT connect to the washer drain unless it also has a vent. HOW you do the venting is the reason we have to go to school to become plumbers, and we do NOT have enough information, from the pictures, to advise you on it. As far as the donut is concerned, if it is NOT tight in the hub or around the pipe, it WILL leak. You probably have the wrong donut, but since it was lead piping the cast iron should be from the era when the hubs were NOT made to fit rubber donuts.
    Last edited: Sep 23, 2011
  14. Layne

    Layne New Member

    Messages:
    16
    Location:
    Bryan, Texas
    Alright guys, I can see your frustration with me after learning how erroneous my intended setup was. I promise I am not a dumba$$ most of the time. I'll have to redo the washer standpipe in the wall so the trap and vent are there. It's a tricky place to vent as it's right where the orignal structure meets an add on room, and there is a valley in the roof right over that area. Might be able to go into the attic and tie into the main vent, but that's all cast iron.

    Here's the rest of the vents. It's a one bath house, the only thing not in this picture is the kitchen sink.

    [​IMG]

    The part I already botched. Yeah I used a vent 90 at the bottom, don't worry I'll redo it. The foot of the bathtub is right on the other side of those studs on the right. The part I'm standing in is a bedroom.

    [​IMG]

    Would this be an acceptable solution so that I can still use the same hole through the wood? Would you place a cleanout at the X location on the vent pipe?

    [​IMG]
  15. Terry

    Terry Administrator Staff Member

    Messages:
    15,416
    Location:
    Bothell, Washington
    You can add a p-trap above the floor here for the washer, and you will still need to separately vent the tub.

    [​IMG]
  16. Layne

    Layne New Member

    Messages:
    16
    Location:
    Bryan, Texas
    Right. I was thinking like this. But do I cap off or T in the pipe marked in green?

    [​IMG]
  17. Terry

    Terry Administrator Staff Member

    Messages:
    15,416
    Location:
    Bothell, Washington
    It would be easier to leave the existing vertical vent in place and add the tee for the tub vent in red.
  18. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    You can put the cleanout ANYWHERE in the vertical pipe. You do NOT have to connect to the existing venting OR go through straight up to the valley of the roof. Offset the vent elsewhere and go through the roof there.
  19. Layne

    Layne New Member

    Messages:
    16
    Location:
    Bryan, Texas
    Ok, problem solved I hope. I put the tub back the way it was (minus the lead trap), and found another place at the end of the 4" horizontal pipe where I can Tee in the washer. I went in the attic to confirm the vent will work out and it looks like no problem. The hub donut was only loose because I had a short piece of pipe in it. Once I put a long enough piece all the way though it drove in tight.

    Next question: Sometime in the past my toilet was replaced and the flange is connected to the cast iron using a rubber coupling with hose clamps on each end. Is this an acceptable practice? I'll be replacing the toilet and the floor under it so I can modify it if neccesary.
    I can see 3 possibities:
    1) leave the coupling as-is
    2) install a hub donut with a PVC pipe and flange
    3) something more difficult... lead in another cast iron flange?
  20. Terry

    Terry Administrator Staff Member

    Messages:
    15,416
    Location:
    Bothell, Washington
    [​IMG]
    I normally just pull the lead out of the cast iron tee, and use a 4x3 flush bush into a insert rubber pipe donut.
    With this, I use a 4" closet flange.

    If you know someone that can pour lead, that would work too.
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