Gas Furnace Vent Above Roof

Twist the roof s vent pipe clockwise one half turn with one hand while holding the gas furnace s vent pipe still with the other hand.

Gas furnace vent above roof.

See the detailed b vent chimney rooftop clearance table below. If your furnace has an afue rating of 90 percent or above it will have a flue pipe that goes. That s because the combustion byproducts are in a gaseous form so the gases can float up through the flue pipe and out of your roof. All gas furnaces must be vented to allow exhaust gases from the combustion process to escape.

If your furnace has an afue rating below 90 percent it will most likely have a flue pipe that goes up through your roof. Vents must be tall enough so burned gases exit above a roof line and cannot filter back into a house. The top of the chimney should be at least two feet above anything within a ten foot radius of the chimney.