A flue pipe is the exhaust vent that carries the dangerous combustion byproducts of a furnace or water heater safely out of the home. For Mobile Home Gas Furnaces, the flue pipe must be specifically rated for use in manufactured housing to handle high temperatures and tight clearances. Modern high-efficiency ACIq furnaces often use PVC flue pipes because their exhaust is cool enough to not melt the plastic. It is critical that the flue pipe is pitched correctly to allow for Condensate drainage and prevent water from backing up into the unit. You can find various venting kits and roof jacks in our Accessories-Kits collection. A blocked or leaking flue is a major safety hazard, as it can allow carbon monoxide to enter the living space. Regular inspection of the flue pipe's joints and exit point on the roof is a mandatory part of any HVAC safety check. It is the primary exhaust system for any gas or oil-fired appliance in your home.