Connecting 4" Cast Iron with 3" PVC

[molo]

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.

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

[Tom Sawyer]

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.

[jadnashua]

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.

[molo]

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!

[MACPLUMB 777]

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