Bossing an 1"1/2 upvc waste pipe into cast iron stack

[Plucky]

Anyone got any ideas on the above.

Situation is I have to replace a bath with shower tray for elderly customer and unfortunately the existing waste is a little higher than I would like so rather than have an upstand into the shower I wanted to boss a new pipe in lower and cap off the old existing copper waste.

The stack is internal and boxed in. I will break out to gain some access but removing a section and replacing with plastic is not an option.

Thanks

 

[darren-]

Pump? Or is that not an option?

 

[ecowarm]

You can get a "timesaver" strap on boss for cast iron

 

[Guest123]

Just drill a neat hole in it with a holesaw and fit a PVC strap on boss. Or as above cut the pipe and use a timesaver.

 

[Bernie2]

Hmm!

Having been required to drill cast in situe over the years to fit bosses, it ain't easy. Its possibly easier but dearer to cut a piece of cast out and fit a proper boss pipe. You can get slip couplers or Time saver couplers that do roughly the same job for cast or could at one time. I would not recommend using plastic if the stack about the boss is cast iron, the weight is usually to much,

 

[Guest123]

Hmm!

Having been required to drill cast in situe over the years to fit bosses, it ain't easy. Its possibly easier but dearer to cut a piece of cast out and fit a proper boss pipe. You can get slip couplers or Time saver couplers that do roughly the same job for cast or could at one time. I would not recommend using plastic if the stack about the boss is cast iron, the weight is usually to much,

A plastic strap on boss is fine and I've done plenty of these without any problems. However I do not recommend cutting the cast iron out and replacing that section with a plastic branch but a timesaver one which is perfect for this. If you cut out a section of the cast pipe make sure it's well supported above and below the cut out section or it will move and be impossible to fix due the weight! The hardest part of fitting a strap on boss is cutting the hole, neatly and to the correct size. Rough drilled edges will cause things to catch on it and eventually cause a blockage. A holesaw for metal is perfect but must be lubricated when cutting so use a spray gun.