How, or Would Schedule 80 PVC compare to that of Sch. 40 in venting a furnace? I’m installing a 90+ furnace and need to run a new Vent and Air pipe system over a heated room with a suspended ceiling.
Would I still need to Armaflex the pipe? Would the thicker schedule 80 PVC encroach on the maximum allowable length of 2″ pipe? I am planning on using the Sch. 80 due to the availability of the pipe. (Shhh… don’t tell work). Thanks Darek.
Hi Dennis, both PVC vent pipe types (Sch40&80) have been certified by the American Gas Association, you can compare markings on your pipe using this table High Efficiency Furnace Plastic Vent Pipe Types .
I’ve never seen a PVC furnace vent pipe insulated in conditioned spaces, it does expand slightly during furnace operation but in a heated room it shouldn’t be a problem (unless your local code requires it).
Make sure that you have a proper support (min every 3′), vent pipe slope towards the furnace for proper drainage (at least 1/4″ per foot), and length / diameter / quantity and type of bends properly calculated – never exceed max allowable length. PVC vent pipe wall thickness – not a factor, not even mentioned in installation manual for American Standard and Trane HE furnaces.