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Thread: Connection ABS drain directly to cast iron pipe

  1. #1

    Default Connection ABS drain directly to cast iron pipe

    Hello,

    I am planning to installing the Schluter Kerdi shower system in my basement shower remodel. After removing all of the old drain hardware the shower stall area, I discovered that the old cast iron drain pipe stub was the perfect height for the Kerdi drain.

    The drain has a 2" ABS solvent weld-on fitting. It slips perfectly over the 2" cast iron pipe.

    My question is can I attach the ABS drain DIRECTLY to the cast iron pipe???

    I am aware that you can use a Fernco-type adapter to go from cast iron to ABS, but that would involve having to cut the cast iron down a bit and installing a section of ABS to attach to the drain. I was wondering if you could somehow attach the ABS drain directly onto the cast iron pipe?

    Is it possible or just a pipe dream???

    Thanks!
    Last edited by Terry; 05-22-2006 at 10:37 AM.

  2. #2
    Plumber Cass's Avatar
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    Pipe dream. they shouldn't fit like that if they are the same size. Measure them.

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



    Lots of things look like they should fit together, but do not. This is one of them. There is no way to make a joint between an ABS fitting and cast iron pipe. In fact from the description of your base, I would not use a glued drain fitting anyway. I would use one with a rubber compression gasket that installs from inside the shower base.
    http://www.oatey.com/shower_drains/101pnc.html
    Last edited by Terry; 05-22-2006 at 08:28 AM.

  4. #4
    Retired Defense Industry Engineer jadnashua's Avatar
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    The Kerdi drain is a special application - Kerdi is a tileable waterproof membrane applied on top of the preslope, then tiled. You must attach the membrane to the special Kerdi drain via thinset, there is no clamp. So, you must make the plumbing connection to the drain through either abs or pvc (depending on which type you buy). I think the only acceptable way to do this would be to tear out the CI p-trap and replace with pvc.
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    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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