DIY Doctor UK DIY Forums

Hi I am helping my mate put in his new toilet. It has a saniflow so the outlet is 32mm and we have to join that to the main stack which I believe is cast iron.

As I understand it we need a boss I see these have two little lumps on them which one of the guys at the DIY store told me you cut the stack hole big enough to encompass these lumps as I call them, not sure what size hole that should be, it looks like it will have to bigger than the 32mm front opening, but have not measured that bit yet.

Anyway apart from that, all the DIY stores seem to have is solvent weld types. Surely if we are joining to cast iron we will need a different kind ( which it seems DIY stores do not keep) or is it possible to use the solvent type anyway? The guy in the store said he thinks you can get ones for cast iron that will take the 32mm plastic pipe but they are really expensive, £35 or something, is this right? In that case definitely is it possible to use the solvent weld type obviously not with the solvent but maybe with silicon or is that not possible, the guy did mention something about the cast iron being bigger than plastic stacks as well.

Some guidance and help would be appreciated please.

Hi Happyhero,
I recently put in my 32mm saniflow(liquid only!!). I also had cast iron soil stack, inside house. I removed a section of soil pipe and replaced it with plastic. It made it so easy. As for the boss collar, mine went around the whole pipe and where the boss meets the soil pipe I used plumbers mate(like putty) just in case repairs are needed. One wife, two kids, no leaks.
Hope this helps
Jackhawk