The Amana Gas Furnace Backfires When Starting

Amana Gas Furnaces

• Amana manufactures mid- to high-efficiency gas furnaces with annual fuel utilization (AFUE) ratings of up to 96 percent, according to WebHVAC, a furnace review site. An AFUE rating indicates how efficiently a furnace converts natural gas into heat energy. Amana brand furnaces use a tubular heat exchanger design that enhances their heat performance capacity. This feature, combined with variable speed blowers and modern pilot ignition systems, helps to distinguish the Amana brand within the heating and cooling industry.

Ignition Delays

• As with other types of gas furnaces, Amana systems use a thermostat, pilot ignition and burner devices to start the furnace. When the thermostat signals the furnace to come on, the gas valve opens so the igniter system can start a flame. Once the pilot lights, a flame sensor triggers the lighting of the burner devices. A delay in lighting the pilot can cause gas to build up in the heat exchanger compartment. The heat exchanger creates an area where combustion gases can vent and also transfers heat from the burners into a home’s duct system. When gases accumulate in the heat exchanger compartment, the build-up can cause the burners to make a loud backfire noise when lighting. A service technician can analyze the problem and replace or adjust faulty components within the ignition sequence.

Furnace Burners

• Over time, a malfunctioning igniter or burner component can cause soot to accumulate where burner flames ignite. Soot develops in cases where condensed combustion gases form along igniter and burner surfaces. As a result, dirty or clogged furnace burners hamper the flow of the burner flame after the pilot flame appears. As gas emissions begin once the thermostat signals the furnace, delayed burner ignition can cause gases to build up in the heat exchanger compartment. Much like with a delayed pilot ignition, once the burners do light up, excess gases cause a backfire noise to sound. Soot build-up along the burner trays can also cause a pressure build-up that eventually gives way in a sporadic pattern. When this happens, multiple backfires may result.

Combustion Air Flows

• Amana gas furnaces feature a tubular heat exchanger design that promotes efficient combustion processes within the heat exchanger compartment. Combustion processes involve transferring return air from a home’s duct system into the heating compartment where furnace burners operate. The burner component also includes a shutter device that helps regulate air flows across burner surfaces. Blockages in a home’s duct system or shutter device can block off normal air flows within the heat exchanger compartment. When this happens, soot build-up may develop along burner surfaces, causing backfires to occur once the burners ignite.