Connecting 4" Cast Iron with 3" PVC

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by molo, Sep 17, 2012.

  1. molo

    molo New Member

    Messages:
    840
    Location:
    cold new york
    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
  2. kreemoweet

    kreemoweet New Member

    Messages:
    371
    Location:
    Seattle. WA
    It is extremely uncommon, and as far as I know illegal (contrary to plumbing codes).
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
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    Location:
    New England
    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.
  4. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,335
    Location:
    Yakima WA
    Just because a store sells it, doesn't make it legal. They still sell S traps at Ace Hardware.
  5. Tom Sawyer

    Tom Sawyer In the Trades

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    3,135
    Location:
    Maine
    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
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,525
    Location:
    Cave Creek, Arizona
    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.
  7. molo

    molo New Member

    Messages:
    840
    Location:
    cold new york

    Thanks for the reply,
    What is a code compliant method for this?
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Location:
    New England
  9. molo

    molo New Member

    Messages:
    840
    Location:
    cold new york
    Last edited: Sep 18, 2012
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,934
    Location:
    New England
    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: Sep 18, 2012
  11. molo

    molo New Member

    Messages:
    840
    Location:
    cold new york
    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.
  12. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,525
    Location:
    Cave Creek, Arizona
    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: Sep 18, 2012
  13. molo

    molo New Member

    Messages:
    840
    Location:
    cold new york
    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
  14. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,525
    Location:
    Cave Creek, Arizona
    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.
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,934
    Location:
    New England
    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.
  16. molo

    molo New Member

    Messages:
    840
    Location:
    cold new york
    Would this be a no-hub street tee? Also by "street tee" do you mean the "leg" of the tee can have a piece of PVC pipe slide right over it?

    Also, what is the problem in using a "Y"?

    Thanks again
    Last edited: Sep 19, 2012
  17. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,135
    Location:
    Maine
    Where is he going to find a street T? I'd bet that of the 6 plumbing supply houses near me, none of them carries a street T in any size. Charlotte and Mueller both say they make them though.
  18. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,934
    Location:
    New England
    The pvc fitting will have hubs on both ends...the street T will only have them on one end. It might make getting the whole assembly just the right length when cutting out a section easier. If you go with a CI hubless fitting, neither end will have a hub. Getting the section of pipe just right - nice square cuts with the proper gap to slide in the fitting will be tougher.
  19. molo

    molo New Member

    Messages:
    840
    Location:
    cold new york
    There is a challenge to using the no-hub couplings that are available at the supply house. They have a "stop" half-way through the fitting (the rubber forms the stop). This "stop" will prevent the coupling from being slid up (or down) the pipe so that the new piece can be placed into the cut out area. In other words, I need a repair no-hub coupling. Are these made, or is there another way?

    Thanks again!
  20. MACPLUMB 777

    MACPLUMB 777 TROJAN WORLDWIDE SALES RP

    Messages:
    679
    Location:
    Houston, Texas, United States
    You take the rubber coupling and roll it back over itself then you
    only need a extra 1/4" or so to slide your tee/wye into place roll rubber back down and slide
    your metal band into place, ! be sure to tighten the nuts equally
    Last edited: Sep 26, 2012
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