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Thread: Anything wrong with this sink addition drain/vent plan?

  1. #1

    Default Anything wrong with this sink addition drain/vent plan?

    Hi all. I'm planning to move the kitchen in an apartment, and need to tap a drain line into existing plumbing of 4" cast iron and 2" galvanized. Any critique or better plan would be appreciated. I don't trust the local plumbers to plan this stuff well, the last odd job it took 3 plumbers to finally get it right. I was advised to take this here for some expert eyeballs.

    Since I don't want to mess with the ancient cast iron, I want to cut into the 2" lav & shower branch to mount PVC T's with rubber couplers. This apartment is identical to the ones above and below on the same vent & soil stacks. I'm not certain why there's a parallel vent coming from the unit below, there isn't a corresponding one from this unit to the one above which is the top floor, but I've only done the exploratory surgery on this unit, as the others are occupied. The run of 2" from the new kitchen sink to the vent is less than 7' so I should be okay with the local National Standard code. I know the vent to vent stack tie in needs to be 24" above the basin top.

    Here's a drawing of the existing plumbing, with the proposed addition in red. Any thoughts would be appreciated.


  2. #2
    Plumber jimbo's Avatar
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    Make sure to use the right fittings: sanitary tee on the vertical to connect the trap arm, wye + 45 on the horizontal tie in.

    Vent can connect 6" about the flood rim of the lav.

  3. #3
    Moderator & Master Plumber hj's Avatar
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    Default vent

    quote; Vent can connect 6" about the flood rim of the lav

    OR 42" above the floor, whichever is HIGHER. Looks like it will work as long as you use a combo or similar to connect to the tub drain, a sanitary tee for the sink, and long radius ells for the horizontal turns. I might consider a "Y" into the main drain riser easier and more direct than trying to connect and pipe to the tub drain.

  4. #4

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    Quote Originally Posted by hj View Post
    quote; Vent can connect 6" about the flood rim of the lav

    OR 42" above the floor, whichever is HIGHER. Looks like it will work as long as you use a combo or similar to connect to the tub drain, a sanitary tee for the sink, and long radius ells for the horizontal turns. I might consider a "Y" into the main drain riser easier and more direct than trying to connect and pipe to the tub drain.
    Thanks for the feedbacks. I've had code hassles here with existing low sink vents, and am pretty sure they want 24", and since it's no problem to do it, I might as well. No plumber I've ever had here has been willing to cut into the 4" cast iron drain risers, the possibility of disaster make it not worth it if it's not supported well. The last job was adding a shower on the 2nd floor of a place and they all preferred running a new 2" line down the chase to a PVC line in the basement.

    What fitting exactly do you mean by a combo? I guess I understand the idea of using a 45 and wye to send the water in the right direction. Like this right?



    What about this long turn wye instead of the wye & 45? With the long radius ell it'd make a nice smooth turn into the drain.

  5. #5
    Moderator & Master Plumber hj's Avatar
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    Default fitting

    THAT is a "combo" and I use them much more often than a "Y" and 1/8 bend. Unless the plumbing is very uniquely done, there are MANY, or at least one which is all it needs, pipes attached to the riser and anchored in the walls which will support it BETTER than any riser clamps. I have cut MANY 4" cast iron risers and cannot remember any that I had to put additional supports under. NO code accepts 24" for the vent connection. Normally 42" is the standard, UNLESS you have some fixture higher than 36" in which case it has to be 6" above THAT one.

    Last edited by Terry; 01-12-2010 at 08:15 PM.

  6. #6

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    Quote Originally Posted by hj View Post
    THAT is a "combo" and I use them much more often than a "Y" and 1/8 bend. Unless the plumbing is very uniquely done, there are MANY, or at least one which is all it needs, pipes attached to the riser and anchored in the walls which will support it BETTER than any riser clamps. I have cut MANY 4" cast iron risers and cannot remember any that I had to put additional supports under. NO code accepts 24" for the vent connection. Normally 42" is the standard, UNLESS you have some fixture higher than 36" in which case it has to be 6" above THAT one.
    Thanks HJ. Combo it is! As for the cast iron, all I know is they REALLY didn't want to cut it. I'm staying away from the the cast iron since it appears I can do it successfully.

    I think we're miscommunicating about the 24". How could a vent 24" above the basin top be no good if 6" is OK?

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    Plumber jimbo's Avatar
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    Quote Originally Posted by hj View Post
    quote; Vent can connect 6" about the flood rim of the lav

    OR 42" above the floor, whichever is HIGHER. Looks like it will work as long as you use a combo or similar to connect to the tub drain, a sanitary tee for the sink, and long radius ells for the horizontal turns. I might consider a "Y" into the main drain riser easier and more direct than trying to connect and pipe to the tub drain.

    I don't know.....CA code ( UPC) 905.3 just says 6" above the flood rim....

  8. #8

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    One more question if you guys don't mind. Since I'll be running the drain from the sink trap around the back of the cabinets to the vented line, do those horizontal ells need to be wide turn, and should I put a cleanout in a sanitary tee by the tee into the vented line like I've shown? It'd be a crawl into the back of a corner cabinet to get to it, but it seems like a good idea anyway.


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    Master Plumber Dunbar Plumbing's Avatar
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    These CAD images are getting better and better, no plumber involved either.

    What a difference from 8 years ago, on the internet.

    It wouldn't hurt to have long sweep 90's but it is not required.
    Read what the end of this sentence means.

  10. #10
    Moderator & Master Plumber hj's Avatar
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    Default drain

    IF you went into the 4" you would not need a cleanout. Doing it your way, you should have one. In fact with all the turns, it would be a requirement to install one. Whether the elbows have to be long turn or not would depend on your code and inspector. Most places would require them.

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    Plumber krow's Avatar
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    I just want to mention that you have too many 90's between the p-trap and your vent. You are only allowed 135 degrees change of direction between the p-trap and your vent.

    In the latest pic above, you have 270 degrees change of direction

  12. #12

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    Quote Originally Posted by krow View Post
    I just want to mention that you have too many 90's between the p-trap and your vent. You are only allowed 135 degrees change of direction between the p-trap and your vent.

    In the latest pic above, you have 270 degrees change of direction
    Again, thanks all. Damn Krow, I don't think I can swing that without running the drain just behind the cabinet doors. It's not like I can put the vent in the wall behind the cabs, it's plaster right on brick. I'll just have to go as is with wide turns and hope they, like most of the commenters so far, don't bother about it.

    Dunbar: I figure in this game a picture IS worth 1000 words! Besides, I use CAD in my day job, so this wasn't tough. I could have easily done it 8 years ago too (or 20), but Sketchup really is an amazingly easy tool. I was even able to download drawings of some of the fittings.

  13. #13
    Master Plumber Dunbar Plumbing's Avatar
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    Quote Originally Posted by gellfex View Post
    Again, thanks all. Damn Krow, I don't think I can swing that without running the drain just behind the cabinet doors. It's not like I can put the vent in the wall behind the cabs, it's plaster right on brick. I'll just have to go as is with wide turns and hope they, like most of the commenters so far, don't bother about it.

    Dunbar: I figure in this game a picture IS worth 1000 words! Besides, I use CAD in my day job, so this wasn't tough. I could have easily done it 8 years ago too (or 20), but Sketchup really is an amazingly easy tool. I was even able to download drawings of some of the fittings.

    You figure out how to make a software program for plumbers and DIY'rs that has a very small learning curve in how to use it, you'll mint your first million in a very short time.

    It would be a great improvement to the plumbing profession across the board. Anything difficult to learn I can't see working.
    Read what the end of this sentence means.

  14. #14

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    Well, as I'm sure you pros know, no plan survives contact with what you find when you cut the wall. Instead of the drains of apt 3L looking like those of 4L above, and 2R & 3R, they're different, as shown in the drawing. The WC and the traps go into one big ass 4" casting that also has a vent arm, that unidentified tie in I mentioned in the 1st post.



    I successfully did plan A discussed earlier for the future sink drain of 4L above, shoving a capped 2" pipe up in the wall for the day I move that kitchen, but doing 3A that way is a problem. Can I just cut into that vent like I've drawn in the closeup below? Why did that 3 way cast iron fitting need a vent anyway? (it's so bizarre I didn't even try to draw it accurately)



    Quote Originally Posted by Dunbar Plumbing View Post
    You figure out how to make a software program for plumbers and DIY'rs that has a very small learning curve in how to use it, you'll mint your first million in a very short time.

    It would be a great improvement to the plumbing profession across the board. Anything difficult to learn I can't see working.
    There's seriously nothing easy out there? With a complete catalog of fittings anyone could do it in Sketchup in a snap. If the fittings and pipe have a centerline built in, you just spin them to the right orientation and drag them by the end of the line to the end of the line on the next fitting. Pipes can simply be stretched out to the right length, and pitched.

    The Sketchup 3d library has a "beginner kit" of fittings, just simple T's and ells in various sizes, but if you download free Sketchup, do the tutorials, and try it, I'll bet you'll get it. When I'm not up to my ass in dust, maybe I'll try to do a tutorial file for you guys.

  15. #15
    Plumbing Designer FloridaOrange's Avatar
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    Quote Originally Posted by gellfex View Post
    When I'm not up to my ass in dust, maybe I'll try to do a tutorial file for you guys.
    I would be interested in that. I use CAD and played with Sketchup but not enough apparently.
    Matt
    Semi-professional plumbing designer
    Enjoying life in SW Florida

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