Furnace Vent Pipe Clearance

What are the allowable clearances.

Furnace vent pipe clearance. American gas association has certified the design of condensing furnaces for a minimum of 0 clearance from combustible materials with a single wall plastic vent pipe. Maximum horizontal section of the furnace water heater double wall vent pipe cannot be longer than 100 of the vertical vent pipe length. Metal single wall generally requires 6 inches of clearance. The clearance between gas vents and combustible materials is listed by the manufacturer but is typically 1 inch for type b.

Clearance is the distance that is considered to be safe between a heat producing appliance chimney chimney liner vent pipe vent connector or other hot surfaces and combustible materials. Furnace water heater vent pipe clearance double wall. I m trying to confirm the necessary clearance for a direct vent concentric pipe on a 95 propane furnace. See direct vents side wall vents for a complete table of recommended clearance distances from a direct vent gas appliance terminal to other building components or features.

Below are the allowable clearances for a number of common situations. Inadequate clearance from combustibles at the gas vent stack for the furnace at the drywall and wooden structural components. I ve checked the vendor literature and don t see the specific senario that i m looking at. Colour illustration of direct vent sidewall terminal clearance distances adapted from american standard furnace installation instructions that in turn cites ansi z223 1 nfpa 54 national fuel gas code for us installations and cites csa b149 1 natural gas and propane installation code for canadian direct vent gas vent installations.

Transite a whitish looking cementious pipe containing asbestos material. Each type of vent pipe has recommended clearances to combustible materials. In my situation there is a three foot space between the edge of a window and a wall. Early 1900 s to about 1975 it was used.