During heating, how is the fan cycled in a gas furnace with an electronic control board?

In a gas furnace with an electronic control board, the fan is typically cycled based on a time schedule after the burner has activated. This means that after the heat exchanger reaches a certain temperature, the electronic control board will turn on the fan to circulate warm air throughout the space, ensuring that the heating process is efficient and effective.

This cycling method allows the system to provide consistent airflow and temperature control while minimizing the chances of overheating the heat exchanger or wasting energy. Time-based cycling is often paired with various sensors to ensure that the operation aligns with performance needs, but the primary cycling mechanism relies on a predefined time interval.

In contrast to other mechanisms like room temperature adjustments or manual controls, which would require constant user input or additional equipment, time-based cycling provides a balance of automation and control suited to maintain comfortable indoor temperatures efficiently.