I am curious about the foil tape on the single wall vent pipe. Is that a requirement in your jurisdiction? I have never seen that as a requirement. The vent for a Catagory 1 appliance is under negative pressure. The IFGC has very little information on installation requirements of single wall "vent" pipe. Very little on specifics as to how sections of single wall vent pipe are to be fastened together, sealed, supported. I am an oldtimer, and we always used at least 3 screws in each joint of single wall vent pipe. Never used tape. Anybody have jurisdiction requirements that go farther than screws in each joint? Such as how often the vent must be supported horizontally? For instance IFGC Chapter 5 vents says All portions of single wall metal pipe shall be supported for the design and weight of the material supported. That leaves a lot up to the discretion of the AHJ.