Flue
What it is
Have central air handling systems, including furnaces, flues and chimneys, inspected annually and properly repair cracks or damaged parts.
The boiler flue (stack) will need to be made of stainless steel to avoid corrosion from flue gas condensate on the inner surface of the stack
Combustion gases and particles also come from chimneys and flues that are improperly installed or maintained and cracked furnace heat exchangers.
Its parts
- Vent connector
- A draft hood is a flanged hood at the base of the flue pipe above the gas water heater tank (Figure 3).
- Draft hood
- A draft hood is a flanged hood at the base of the flue pipe above the gas water heater tank (Figure 3). It has openings around the base of it under the hood that allow air from the surroundings to enter the flue pipe where the air gets heated by the emissions from the tank burner.
- Type B vent
- Type B vent is double-wall pipe for gas- or propane-fired combustion appliances. An air gap between the pipes acts as an insulator. The inner vent pipe is aluminum and the outer is galvanized steel.
- Backdrafting
- A newer type of Category 1 furnace has an induced draft fan that pulls air through the combustion chamber, which assists in getting a draft started and encourages more complete combustion for higher efficiencies of 80% to 86%. However, because the furnace still relies on negative flue pressure to carry away combustion byproducts, the induced-draft furnace can, like the naturally drafted furnace, have the potential to backdraft.
- With a sealed combustion chamber and separate air intake, it is almost impossible for these types of water heaters to backdraft harmful flue gases back into the house.
- Combustion air
- Building America recommends using a sealed-combustion, direct-vented system that draws its combustion air from outside and pushes exhaust flue gases outside.
- Atmospheric drafted (also called naturally drafted) furnaces use the heat in the flue to draw combustion air through the furnace and to lift combustion exhaust up and out of the chimney.
If it may be unsafe
If you smell gas, leave the house and call Peoples Gas at 866-556-6002 or 911 from outside. If your CO alarm sounds or anyone feels sick, leave and call 911 from outside.
AirLogic is not an emergency service.
Related pages
- Glossary: Flue
Its entry, and the guide's pages that use it.
Sources
- U.S. EPA. Sources of Combustion Products.
- U.S. Department of Energy. Boiler Replacement Package Performance Requirements, Savings and Costs (DOE Building Technologies Office).
- U.S. Department of Energy. PNNL Building Science: Look for Signs of a Gas Water Heater Backdrafting.
- U.S. Consumer Product Safety Commission. Inspecting Your Home Heating System Before Winter Could Save Your Life.
- U.S. Department of Energy. Combustion Appliance Safety & Efficiency Testing.
- U.S. Department of Energy. Pre-Retrofit Assessment of Combustion Appliances.
- U.S. Department of Energy. Gas Storage Water Heaters.
- U.S. Department of Energy. Gas Storage Water Heater.
- U.S. Department of Energy. Direct Vent Equipment.