What is Flue?

Definition of Flue in Construction
Flues are located within chimneys. Confusion between the two terms is very common.

A chimney will incorporate a number of flues.

A flue is the hollow assembly, could be a pipe, built up tile pipe, or any other type of noncombustible material that can be assembled to vent the exhaust gases, smoke or fumes from a heating component, such as a boiler, hot water heater, furnace or fireplace. The flue needs to be air tight along its length and open at the top to properly work. A natural draft will be created within a flue to vent the exhausts from any of the heating components. The failure of a flue can cause a fire and the build-up of solids within the flues interior can also cause a fire condition. It is important to keep flues clean of all soot and build up on the interior. The material that accumulates within a flue system for a wood or coal burning heat source is called creosote. This material is highly flammable and can cause fires, if not properly removed from the interior of the flue pipe.