connecting plastic to cast iron stack

[micktamas]

I have a cast iron soil stack with cast iron branch to wc.I need to replace the branch with 4\\\" 110mm as it is corroding and is only 3\\\" diameter ( problems flushing big waste away) Could you tell me if I can connect a plastic branch into soil stack and if so how and how do I remove the cast iron branch,someone told me to grind the cast iron out and fit the plastic in, then make it good with putty is this correct?

[ChrisR]

There are a few methods, as k in your nearest decent plumbers merchant. There's a rubber Branch which goes in where your CI one is and has jubilee clips round the 3 pipes. Looks naff though.

It's much neater and not too difficult to replace the whole stackpipe.

[kevplumb]

micktamas wrote:

I have a cast iron soil stack with cast iron branch to wc.I need to replace the branch with 4\\\" 110mm as it is corroding and is only 3\\\" diameter ( problems flushing big waste away) Could you tell me if I can connect a plastic branch into soil stack and if so how and how do I remove the cast iron branch,someone told me to grind the cast iron out and fit the plastic in, then make it good with putty is this correct?

bit more info might help as in what size is the stack

__________________
a little thanks

goes a long way

[micktamas]

Hi the main long soil stack is 4" diameter with a 3" tee off to wc this is about 12" long from where it goes into the house, there is a coupling ( I think that is what it is) on this pipe and that is where it is starting to corrode

[kevplumb]

would agree with chris r on this one

__________________
a little thanks

goes a long way

[micktamas]

I did think about replacing the whole stack but there is the weight issue and also I am unsure how to take it out of the ground

[ChrisR]

It'll be cemented onto a conversion piece, at or just below ground level. You wiggle the CI slightly and lift it out, and remove the cement. I've siliconed the plastic in but there's probably something pukka for it.

[kevplumb]

replace it from the branch then (mind your head )

__________________
a little thanks

goes a long way

[micktamas]

Would you remove the stack as one length or in sections

[kevplumb]

depends how brave you are and the amount of room you have to play in cut it in sections and remember its heavy

__________________
a little thanks

goes a long way

[micktamas]

many thanks to you both might give it a go one day soon

[doitall]

I would just cut the bad bit out and replace with timesaver cast iron branch and sockets

[htgeng]

doitall wrote:

I would just cut the bad bit out and replace with timesaver cast iron branch and sockets

Im sure someone has mentioned it before, but what is the preferred method to cut cast iron. I've got such a job coming up. I have to install a ground floor loo so need a branch at ground level. Think I may need to go a step further than what Chris suggested and try to chisel out the concrete since I need to be close to ground level for the right drop. 1:40 right?

[ChrisR]

Most folk use an angle grinder. 9" won't do it in one cut but after removing some pipe on the waste side you can end up with a square cut.

Take old stack down from the top. It usually wiggles apart, wall fixings and all. Not so heavy that you can't hold a length in one hand.

[joshgroeny]

doitall wrote:

I would just cut the bad bit out and replace with timesaver cast iron branch and sockets

Hi - interesting thread. I need to join a new pipe into my cast iron stack and I need the timesaver CI branch. Where can I find one?

Thanks,
Josh