Picked up a used Fahrenheit furnace today. It came with some of the venting I'll need, but not all. I have a 4 inch cleanout tee, a 3 inch section that connects the exhaust outlet to the cleanout tee and a few 2 foot sections of 4 inch venting. And a couple 4 inch type B elbows, which I already threw in the trash. It's made by SPX/Security Venting (P/N on the 2 foot sections is 4SPL24), which appears to be a division of Lennox Hearth Products. Without dragging on, is it worth it to keep what I have and get the remaining pieces I need of the same brand, or should I replace it all with something "better" such as Duravent? I used Selkirk when I installed my insert years back. I'm not opposed to buying all new, but if I can save what I have I'll use the extra money to buy more pellets.