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Thread: Connecting 4" Cast Iron with 3" PVC

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  1. #1
    DIY Senior Member molo's Avatar
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    Default Connecting 4" Cast Iron with 3" PVC

    Hello,
    I have a vertical 4" Cast Iron piece that I want to connect a horizontal 3" PVC drain to. The local store has a "saddle" with a gasket on the inside and u-bolts that will wrap around the CI. The connection will be at approximately a 90 degree angle. So, the material in the PVC drain will travel horizontally at 1/4"/ft. and then drop down into the CI. Is this a common and good way to make this connection?

    Thanks,
    Bill
    "Any American who is prepared to run for President should automatically, by definition, be disqualified from ever doing so."
    Gore Vidal.

  2. #2
    DIY Senior Member kreemoweet's Avatar
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    It is extremely uncommon, and as far as I know illegal (contrary to plumbing codes).

  3. #3
    Retired Defense Industry Engineer jadnashua's Avatar
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    I'm not a plumber, but if I had to do this, I'd probably cut out a section, then insert a wye using no-hub connectors. Now, there may be an issue with putting pvc in the middle of the run because of the weight. If the pipes are properly braced, that shouldn't be a problem. But, you could put in a CI hubless wye, then convert to pvc, and all would be well.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  4. #4
    In the Trades Gary Swart's Avatar
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    Just because a store sells it, doesn't make it legal. They still sell S traps at Ace Hardware.

  5. #5
    In the Trades Tom Sawyer's Avatar
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    They sell S traps because it's legal to repair or replace and existing one. Now if you want to talk about the plastic accordion tail stocks LOL
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

  6. #6
    Moderator & Master Plumber hj's Avatar
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    1. It is an illegal connection. ALL plumbing codes prohibit "saddle connections" except for connections to the main sewer in the street.
    2. It is also a bad connection function wise.
    3. Cutting a 3" round hole in a 4" cast iron riser will be a very time, and tool, consuming process.
    Licensed residential and commercial plumber

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