I am considering the installation of a saniflo upflushing style toilet a saniplus to be precise. I need to vent the unit. I have a chase up to the attic next to the existing cast iron vent stack. I can run the pvc up to the attic I assume but the vent pipes that tie into the cast iron main vent pipe are like a galavanized pipe. I am looking for the best way to tie into these vent connections. Should I cut out a section of pipe and insert a pvc wye fitting to connect the pvc vent pipe?
Thanks in advance for you advice.
"What if the hokey pokey really IS what its all about."
WOW - You are lucky you can chase a pipe up to attic. You could couple to existing stack. It would be easier to just put a new hole in the roof. Probably cheaper too. Just flash it properly of course.
Cutting the stack could cause problems depending on where the weight is supported. You also need special tools to cut it. Connections are now easy with rubber/stainless "no hub" connectors.
Actually I don't think, once I was in attic, I would try to tee into the cast iron. I would probably cut the cast iron and replace the roof penetration with PVC. That way you do not need to worry about more than once CI>PVC connection and you do not have the weight of the stack above to support.
So - Either new penetration or new stack from attic up is how I would do it.