Double-wall vents pipes are used for ventilating gas appliances that have draft hoods and other appliances such as water heaters, space heaters, boilers and furnaces. Double-wall vent pipes can be used to form an uninterrupted passage between a gas appliance and a vent above a structure’s roof.
A vent pipe constructed with a double wall offers health and safety protection and is economical, efficient and easy to install. Double-wall pipes allow for the fast removal of flue gases because they are able to reach operating temperature rapidly. Reflective aluminum in the inner wall of the pipe heats quickly to contain any gases inside. However, pipe made of materials such as cement, brick or asbestos requires a longer time to warm and function properly.
An insulating air space between the inner and outer pipes helps to cause warmed flue gases to rise. The outer pipe, made of galvanized steel, resists corrosion and offers durability, strength and safety. A building structure can be kept free from condensation damage and pollution if the rise of flue gases is effectively maintained by using a double-wall vent pipe. Double-wall vent pipes should not be used with coal or wood burning appliances or for venting at high temperatures.