I have a quick question regarding the remodeling of my kitchen. I have an 85 yr old home that has the 1.5" vent pipe coming up out of my kitchen counter and going up into the ceiling and taking a few turns before exiting the roof. I am planning on ripping out the plaster, reworking the wiring and hiding the vent in the wall as well as insulating. I am wondering if I should use a 1.5" or 2" vent for this sink with disposal and dishwasher when I tuck the piping into the wall. The old drainpipe is galvanized which is shot and needs to be pulled. Also, does it matter if the vent pipe exits the roof midway up, or do I need to direct the vent out at the peak as it is currently set up? And what size would I need to bump the vent up to at the roof to prevent freezing/frosting over during the cold Wisconsin winters? Any advice would be helpful.