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Thread: Tying into old cast iron sewage line.

  1. #1
    DIY Junior Member PleX's Avatar
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    Default Tying into old cast iron sewage line.

    I'm currently remodeling our house and I'm finally at the master bathroom. I got a quote from several local guys all for around $1500-$2500 which is outside my budget. To be fair, their quotes included moving the water lines as well. Moving the water lines isn't an issue.

    I finally pulled up the patch on the sub-floor to get to the plumbing (I'm moving the toilet and bath drains) and I came across this:

    http://i.imgur.com/aFKSLDI.jpg

    The toilet will be moving 6 feet to the left and the vent will be staying where it is.

    More pics just for reference:

    http://i.imgur.com/kDQ2vnw.jpg

    http://i.imgur.com/i4qRmXS.jpg

    I'm thinking about replacing the vent pipe and everything else with PVC(DWV 40?) as well as part of the stub off the main sewage line.

    My question is, if I cut the cast iron right past the part where if flanges out, can I use a Fernco? coupling on that stub for the sewage? Is there a better way to do it? My concern is that could catch some of the sewage and eventually lead to a blockage.

    The toilet is moving almost 6 feet away so I have plenty of room to make sure it slopes properly and almost three feet of crawl space underneath.

    The reason I want to replace the vent pipe is the half wall it will be in is going to be covered completely (after I repair the sub floor and wall it's currently in) and I don't want the Fernco? on the old sink drain somewhere I can't access.

    Also, if the supply line for the toilet was placed in the wall, it would be really close/right on to the electric line/box so I'm thinking of bringing it up through the floor. Any suggestions?

    I'll be calling a few plumbers tomorrow and the county to check on code/practicality just to make sure. Just looking for some advice in the meantime.

    Thanks in advance.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    A properly installed nohub fitting (Fernco is a brand name...they make thousands of products) is what you'd use to connect between CI pipe and PVC. An alternative would be to take the CI out of the hub, and use a properly sized donut (Fernco makes these, too). Both of these are approved, and if installed properly will outlast the house. IF the ends of the pipe are cut square and clean, the stop in the nohub fills the joint between the two pipes...it's essentially a smooth joint - probably even smoother than pvc-pvc with a coupler.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    Moderator & Master Plumber hj's Avatar
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    The "vent" for the toilet seems to be horizontal, which is NOT code approved. Since you intend to remove a lot of the old stuff, it is irelevant and the pictures have no purpose. Show us HOW you intend to do the new piping and we might have an opinion. However, IF you intended to do it yourself, don't bother calling me, because I will NOT tell you how I would do it, at least until we had a contract and deposit.
    Last edited by hj; 03-10-2013 at 03:16 PM.
    Licensed residential and commercial plumber

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    DIY Junior Member PleX's Avatar
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    Quote Originally Posted by jadnashua View Post
    A properly installed nohub fitting (Fernco is a brand name...they make thousands of products) is what you'd use to connect between CI pipe and PVC. An alternative would be to take the CI out of the hub, and use a properly sized donut (Fernco makes these, too). Both of these are approved, and if installed properly will outlast the house. IF the ends of the pipe are cut square and clean, the stop in the nohub fills the joint between the two pipes...it's essentially a smooth joint - probably even smoother than pvc-pvc with a coupler.
    Thank you!

  5. #5
    DIY Junior Member PleX's Avatar
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    Quote Originally Posted by hj View Post
    The "vent" for the toilet seems to be horizontal, which is NOT code approved. Since you intend to remove a lot of the old stuff, it is irelevant and the pictures have no purpose. Show us HOW you intend to do the new piping and we might have an opinion. However, IF you intended to do it yourself, don't bother calling me, because I will NOT tell you how I would do it, at least until we had a contract and deposit.
    The vent pipe currently runs horizontal until it meets the vertical stack and exits the roof. The second and third picture show where it is and where I would like to keep the vent? as it works out well.

    The toilet will be close to where I drew the circle in the third picture.

    The house was built in 1960 I don't know WTF was to code then and I don't know what is now. Which is exactly why I said I was calling them.

    I paid the last dude who came out for some advice on running the water lines. I understand the business/responsibility side of it dude, experience/know how doesn't come cheap.

  6. #6
    Test, Don't Guess! cacher_chick's Avatar
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    A vent can only be turned horizontal after it is at least 6" above the flood rim of the highest fixture which it serves or 42" above the floor, whichever is greater. It has been this way since before I was born.

  7. #7
    Retired Defense Industry Engineer jadnashua's Avatar
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    I didn't look at your pictures... To be a vent, it must come off of the trap arm before that drops down. Depending on the diameter of the pipe, there are distance restrictions to where the vent must go up - it's longer for larger pipe. The idea is to ensure that there's still an air path, and at 1/4" per foot drop in a normal drain line, and they don't expect the pipe to be full, they've established limits.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Junior Member PleX's Avatar
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    Quote Originally Posted by cacher_chick View Post
    A vent can only be turned horizontal after it is at least 6" above the flood rim of the highest fixture which it serves or 42" above the floor, whichever is greater. It has been this way since before I was born.
    If I understand this correctly, the vent pipe as I keep calling it should only be horizontal after it's 6" above the overflow holes/top of the rim in the sink? or as you said, 42" above the floor?

    In this house, it comes right off the toilet drain which drops straight down. The horizontal portion is under the floor in the crawlspace and then goes off for roughly 3 feet and goes up through the roof.
    Last edited by PleX; 03-10-2013 at 04:46 PM. Reason: Should Google More Before Replying.

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    Forum Admin, Expert Plumber Terry's Avatar
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    There is plenty of old stuff done wrong. Sometimes it's easier to just cut it out and start over.

    A shielded coupling like a Misson works well going from cast to plastic. The metal wrap keeps the pipe from shifting out of line.
    I would measure the OD of the cast you have first. If it's something like 4-1/8", that's like a copper size. New plastic pipe is more like 4-3/8"
    In that case I pick up a copper x cast coupling.

    Last edited by Terry; 11-07-2013 at 03:48 PM.

  10. #10
    DIY Junior Member PleX's Avatar
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    Quote Originally Posted by Terry View Post
    There is plenty of old stuff done wrong. Sometimes it's easier to just cut it out and start over.

    A shielded coupling like a Misson works well going from cast to plastic. The metal wrap keeps the pipe from shifting out of line.
    I would measure the OD of the cast you have first. If it's something like 4-1/8", that's like a copper size. New plastic pipe is more like 4-3/8"
    In that case I pick up a copper x cast coupling.
    Thank you!

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