What device starts operating first when there is a call for heat in modern gas furnaces?

In modern gas furnaces, when there is a call for heat, the blower motor is typically one of the first devices to activate. Its primary purpose is to circulate air throughout the system and ensure that the heated air reaches the living spaces efficiently. By starting the blower early in the heating cycle, the furnace can enhance the heat transfer process, allowing for more effective and immediate warmth in the home.

Starting the blower before the ignition ensures that the airflow is established, which is critical for the combustion process and the overall efficiency of the system. It prepares the pathway through which heated air will flow once the combustion begins. This preemptive operation also helps in achieving a more consistent temperature in the space being heated.

Other components like the gas valve and igniter will operate shortly after the blower begins. The gas valve opens to allow gas to flow, and the igniter or pilot light activates to ignite the gas. However, the blower starting first helps in efficient heat delivery and maintaining a steady flow of warm air when the furnace reaches the desired temperature.