I have 2" steel vent pipe from my sink to the cast iron stack at home.
If I need to reroute this vent run to the stack, can I use PVC or do I need
to stick with steel piping?
I might have trouble unthreading the steel pipe, so I was thinking of cutting
it and using a PVC compression coupling.
Would it be agianst code to use a compression coupling to connect the steel
pipe to the pvc pipe In a hidden wall?
If at all possible get rid of all the old cast and steel that you can. It will leak and plug up at some point.
There is no "compression" fitting for steel pipe. Going to just need a hubless connector, also called a Furnco. http://www.plumbersurplus.com/Prod/L...160422/Cat/429