Mating CI to PVC

[pcleiter]

I am in the process of remodelling a powder room to make it into a laundry area on the ground floor of my home. I am hoping to utilize the existing drain entrance point, which was previously used for the toilet, as the drain for the sink. Therein lies question #1 - is there any reason code-wise, practical-wise, or otherwise which would make this a bad idea or just not advisable? Question #2 is this: How can I go about making the connection from the existing cast iron to PVC pipe? I picked up a Fernco Donut adapter 3" SV CI to 3" PVC but when I put the adapter into the CI pipe by itself, it buckles due to the difference between its OD and the pipes ID. When I put a piece of PVC into it and put it at the mouth of the CI pipe, the only part that will go in is the very edge of the donut. I've read elsewhere in the forum that these things can be a real chore to get in place, but I think that something may be missing in my situation - like maybe the bell collar on the CI pipe? Question #3 - Other than removing the flange from the pipe, is there anything else that I should do to it for the conversion?

Thanks in advance.

(I have attached two photos of the existing drain.)

 

[Gary Swart]

You're going to have to remove the toilet flange. I don't know what kind of access you have under the floor, but if possible go under the floor and cut the cast iron before it enters the closet bend. Then make the transition to PVC pipe. Assuming the toilet was vented, that part of the conversion is taken care of. You do have to trap the sink, but once you have made the transition from cast iron to PVC, it shouldn't be too much problem. But that flange has to go. There's no way connect anything but a toilet to a toilet flange. If there is no access from below, you may have to remove sub flooring to access the drain line below, but that shouldn't be a major problem. Take out what is necessary to gain access, then replace it with a piece of plywood.

 

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[Mikey]

There's no way connect anything but a toilet to a toilet flange.

"No way" is kind of strong. You could manufacture a transition fitting from 2" PVC to a toilet flange, likely using using a wax ring to assure the seal. I'd have to spend a few minutes browsing in Lowe's to check, but I'll bet it could be done mostly with standard fittings and pipe. At worst, you'd have to machine an adapter in the mess somewhere, and think of the enjoyment watching the inspector wonder what to do with it.