Hello, I am a newbie here and trying to purchase my piping online, here is my situation: I need 25" of length and 23.5" of rise so far I have a 3" to 4" adapter, the appliance connector which togther give me 5.5" of length, so that leaves 19.5" of length I need. I also have the pipe that goes outside, not sure how much length that gives me. so far my parts list looks like this: 1 4PVP-E90 1 4PVP-T 1 4PVP-12A 1 4PVP-18A make sense, or am I way off base? thank you!!