I once attempted to use a Fernco coupler to connect my cast iron waste stack to new PVC. My town's plumbing inspector told me Fernco connectors are not "legal." He was not willing to tell me what I needed to use, but referred me to the UPC. Someone at the plumbing supply store told me that I needed a no-hub connector. I used that and passed the inspection.

I didn't really see much difference between the two, but obviously they have different uses.

For the project I'm working on now, I need to connect new 2" pvc to old 1-1/2" galvanized steel pipe. This is a vent pipe for a kitchen sink. My questions -

1) Can I use a reducing Fernco coupling? I'm wondering if it was illegal before because it was a 4" waste stack?

2) Is it "legal" to reduce my new pvc vent from 2" down to 1-1/2 to fit the old galvanized?