I was hoping I could get an experts opinion here because I think my "experts" took a shortcut. The PVC exhaust pipe coming out of my furnace passed through the black flange and ended flush with the black flange. They then had the black coupler/ fernco clamped over the black flange, that has ribs on it, and on the PVC pipe on the left. I'm no expert but I would think that there is no way that rubber coupler is supposed to clamp onto that black flange that is not smooth on the outside with the ribs. I replaced the PVC with a longer piece that passed through the flange so the coupler could clamp onto round flat PVC on both sides. That's when I noticed the rubber coupler was 2" on one side and 2.5" on the other. My guess is that it is the only size they had on the truck so they made it work. Hopefully my attached pictures tell the story a little bit better. I have had enough problems that I'm sure the contractor will just tell me it's fine. Thank you in advance!
