Furnace Flue Pipe Roof Clearance

Inadequate fire clearance from combustibles may not be obvious until you open a door such as our client is pointing out in this photograph.

Furnace flue pipe roof clearance. In contrast modern high efficiency condensing furnaces exhaust much cooler gasses and need only plastic pipe materials such as pvc cpvc or abs for their exhaust vents some high efficiency furnaces also include a plastic pipe for intake area and all types. Clearance distances for chimneys that are 10 ft 3 1 m or more away from the roof ridge measured at the up roof side of the chimney. Clearance from combustibles ranging from 0 to 18 to 36 typically depending on the fuel type electric gas oil. Transite generally requires 1 to 3 inches depending on various factors.

There are several gas or oil fired heating furnace clearance distance types. 9 is a typical clearance between a gas fired boiler or furnace flue connector and combustibles. Trim back the wood shift the vent or. The top of the flue opening should be at least 10 ft 3 1 m away from any roof surface or other structure.

Table of type b vent rooftop clearance requirements. The top of the chimney should be at least two feet above anything within a ten foot radius of the chimney. Vent caps 12 and smaller may terminate a distance above the roof if 8 feet or more away from a vertical surface as follows. The pipes can be set in two ways.

See the detailed b vent chimney rooftop clearance table below. Horizontally through the sidewall or vertically through the roof. Metal double wall b vent requires 1 inch minimum clearance 3. Furnace water heater vent pipe clearance double wall typical listed and labeled double wall vent pipe clearance to combustible materials is one inch but you should always check before installation.

The 1992 vent sizing tables require that all type b gas vents terminate above the roof with a listed cap or listed roof assembly in accordance with the manufacturer s instructions. Except for flat and very low slope roofs such as those listed in the table below b vents should be at least two feet above the roof surface as well. Traditional gas fired forced air furnaces produce hot combustion exhaust gasses and therefore need metal vent pipes or chimneys. Maximum horizontal section of the furnace water heater double wall vent pipe cannot be longer than 100 of the vertical vent pipe length.

When compared to the natural vent this one is more flexible although it is also costlier.