I'd like to reuse the current copper vent pipe inside the wall. I have no sound reasons for wanting to reuse the pipe other than I just like the idea of reusing old materials rather than always buying new, even if it adds to the cost of the job. We'll be asking the plumber about this, and I anticipate that his answer will be that it is way easier and cheaper to just run new PVC inside the wall than trying to clean up the pipe enough to sweat new couplings on as sections of the pipe are stuffed up the wall cavity.
Also, current waste pipe for the toilet is 3" (I think) copper. This had to be cut in one place as part of the renovation, so it would only take one coupling to reconnect the existing waste line to the new stuff.
So my question is, how hard is it to sweat a 2"+ diameter copper pipe? I've done plenty of 1/2" and 3/4", so I know how easy it is to do that, but does it become exponentially more difficult to sweat larger diameters? Is the plumber going to run screaming from our house if we ask him to do this? I assume he will want to just rip everything out and re-run PVC, so should we let him do this?
Thanks for any insight anyone can give me.