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Thread: Connecting 4" Cast Iron with 3" PVC

  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).

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    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

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    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.

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    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]

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    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

  7. #7
    DIY Senior Member molo's Avatar
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    Quote Originally Posted by hj View Post
    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.

    Thanks for the reply,
    What is a code compliant method for this?
    "Any American who is prepared to run for President should automatically, by definition, be disqualified from ever doing so."
    Gore Vidal.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    I think that this would meet code anywhere... http://www.charlottepipe.com/Product...?product=00218 You'd need some no-hub connectors and to rent a snap cutter. You'd also want to buy and install some hangers to hold the upper pipe from falling when you take out a section.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  9. #9
    DIY Senior Member molo's Avatar
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    Thanks jad,

    Is this what you mean by no hub (link below)? Also, If I cut the CI there will be another 15' of CI above this point. Could someone recommend a riser clamp that will be able to be supported (either at the floor above or from the floor in the room)? Here's a pic of some, are these good? http://www.creativehomeowner.com/ind...ectid=chplm167
    Thanks again!

    http://www.google.com/imgres?imgurl=...QEwBg&dur=2776
    Last edited by molo; 09-18-2012 at 04:15 PM.
    "Any American who is prepared to run for President should automatically, by definition, be disqualified from ever doing so."
    Gore Vidal.

  10. #10
    Retired Defense Industry Engineer jadnashua's Avatar
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    Yes, those connectors are what is required. The riser clamps may require opening the wall above. If it goes through the middle of a stud bay, you can just install it using the floor as the support, otherwise, you have to get creative. A tall stack of CI can weigh hundreds of pounds. Now, the horizontal offshoots may support it, but it also could sag considering lead is maleable...so, it needs to be supported BEFORE you cut anything. Convert to pvc at the outlet of the wye using another nohub connector.

    Word of warning, the snap cutter usually makes a fairly decent cut, but if the pipe is particularly old and maybe thin, it can shatter. If the tool is well used, the cutter teeth may be a little dull, making a nice cut harder. It literally squeezes the pipe with what looks sort of like an oversized bike chain with round beveled disks placed around it. Those come to a point and when tightened, produce immense pressure which, once you get it tight enough, will crack the pipe at that point. Once you have the section cut out, you may need to grind things to get the edges smoother, but if you're lucky, you won't. Depending on the tool, you may need to be careful keeping the chain nice and straight until it gets tight...the straighter you start out with, the cleaner the cut. They usually don't have a huge amount of side-to-side play, but again, when old they get stretched, and it can make a difference.

    I've rented one at HD a couple of times. They don't tend to get a lot of use, and the ones I've gotten were nearly new. Your results may differ! From start to finish, a cut only takes a couple of minutes once you figure out how it goes together (it's pretty simple). So, often, you only need an hour or two for the rental depending on how far away it is.
    Last edited by jadnashua; 09-18-2012 at 05:01 PM.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  11. #11
    DIY Senior Member molo's Avatar
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    Thanks again Jad,
    I'm leaning toward a CI wye because of the weight. I'll have to see if the local supply houses have them. Either way I will be clamping and bracing the CI riser.
    "Any American who is prepared to run for President should automatically, by definition, be disqualified from ever doing so."
    Gore Vidal.

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    Moderator & Master Plumber hj's Avatar
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    You may want a no-hub sanitary tee rather than a "Y". In almost EVERY case the piping connected to the cast iron in the wall, and at the toilet will support it without any additional bracketing. I have cut into many cast iron risers and have never used riser clamps on any of them. IF the pipe went directly from the basement to the roof, without any connections, it MIGHT need a support, but even then the "hubs" would probably support it from a top or bottom plate. But you would not need a 4" riser if there were no connections to it.
    Last edited by hj; 09-18-2012 at 06:03 PM.
    Licensed residential and commercial plumber

  13. #13
    DIY Senior Member molo's Avatar
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    Thanks for the input HJ. Do you think that a PVC san-tee would work, or should I be using a CI san-tee?

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

  14. #14
    Moderator & Master Plumber hj's Avatar
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    Either one, but a cast iron one will not need as much of the pipe cut out to fit it in. If you use PVC, or ABS, get a "street tee" so you only need a piece of pipe on the top end.
    Licensed residential and commercial plumber

  15. #15
    Retired Defense Industry Engineer jadnashua's Avatar
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    Some places don't want pvc stuck in the middle of a CI stack. But, if it really is self-supporting, there should be no excessive pressure on it.
    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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