I read some of the other posts regarding CI to PVC. I get the general idea. What is the correct connector for this situation?

Greetings. I am in the midst of a bathroom remodel. I have removed the old, rusted, deteriorated cast iron pipe. The old pipe was a 3" which lead to a 3" cast iron pipe fitted into a 4" PVC pipe that drains out to the city sewer. I want to put 4" PVC back in the bathroom toilet drain. My problem, is that the cast iron pipe that the toilet drained into, also has the rest of the house draining into it also. The upper portion of the iron pipe reminds me of an octopus, with leads into a central area of the pipe.
So, I have a 3" iron pipe that is tied into a 4" PVC that leads to the sewer system. The plumbing vent pipe is within reach so that I can attach the PVC and still have the metal pipe extend upwards through the walls and roof.

Any and all assistance is appreciated.

PD01

If need be, I can upload a photo.

Please, post photo. Thanks

But in the interim: Fernco connectors can be used in your situation. They sell them to fit any size and type of pipe. Home Depot carries the basic ones; you will probably have to go to more professional store to get the other sizes.

Please, post photo. Thanks

But in the interim: Fernco connectors can be used in your situation. They sell them to fit any size and type of pipe. Home Depot carries the basic ones; you will probably have to go to more professional store to get the other sizes.

Here are a couple pic's that show the junction I am described.

15598

15599

15600

Thanks for the visual...

Cut out the Multi-Y fitting. Remove the vertical pipe from where it connects to the 4" PVC . Also cut it below the ceiling. Leave yourself enough space so you can reconnect new pipe to it. You will be using 4"Cast Iron to 4" PVC Fernco fitting.

Now, if I understand correctly, you want to upgrade toilet line to 4", get rid of the Multy-Y fitting and rest of the Cast Iron vertical drop. Run new horizontal toilet drain in 4" PVC below the ceiling. When you get to horizontal to vertical drop (where the Multy-Y used to be), use 4" Double Y fitting. One side will connect to your toilet with using street 45 fitting.

The other side of the Y will connect the two 2" PVC drains. But first, you have to Combine those two into one pipe, about a foot before they reach the new 4" double Y. You combine them by using 2" Y and 2" street 45 fittings. Once combined, you will continue with on pipe towards your new 4" Double Y. There, glue in 4" x 2" reducing bushing into the other inlet of 4" Double Y, glue in short piece of 2" pipe pointing upwards, then 2"-45 fitting that will get you from vertical to horizontal - and connect the 2" horizontal run to it.

I think that the 1 1/2" galvanized drain on the left is capped off. If so, disregard it. If it is active drain, than glue another 4"x 1 1/2" Y immediately bellow the new 4" double Y, pointing towards the concrete wall. Glue in 1 1/2" - 45 and connect.

Install 4" Clean Out on vertical run, before the new 4" pipe turns from vertical to horizontal.

You will have to support the new pipes. You could run the vertical pipe closer to the wall and attach it there. If it is active area, you should also protect the vertical drop from being damaged. In this case, you can run two 2"x 6", one from each side, floor to ceiling.

(note: the drawing should read 4" toilet instead of 3" toilet )