I am replacing a intertherm furnace in a modular with a intertherm furnace do I need to replace the venting and roof jack or can I just reconnect them and if I do need to replace them why is that, I don't deal much with modular furnaces usually just deal with standard residential equipment
talk to Intertherm. probably need to replace them. they are VERY finicky when it comes to venting. may cause pressure switch tripping problems and lighting problems if you don't. has to do with the amount of combustion air that enters thru one of the pipes and back pressure on the other. uses a concentric vent setup from what I have seen.
"Cut it twice and it is still too short".