How is the fan cycled during heating in a gas furnace with an electronic control board?

In a gas furnace equipped with an electronic control board, the fan is cycled based on pre-programmed time intervals to optimize heating efficiency and comfort. During the heating cycle, the electronic control board manages the sequence of operations, monitoring various parameters such as temperature and system diagnostics. After the furnace ignites and begins to produce heat, the control board will activate the fan after a designated time delay to ensure that warm air is circulated throughout the space efficiently.

This time-based cycling helps protect the system components, allowing the heat exchanger to warm up before the fan distributes the heated air. This approach minimizes the risk of blowing cold air into the living space and enhances system longevity by preventing excessive cycling that could lead to wear and tear.

The other methods, such as temperature-based activation, involve turning on the fan in response to specific temperature thresholds, which is not the primary method in standard modern gas furnaces with electronic controls. Pressure triggers often relate to safety mechanisms rather than regular operational cycling of the fan. Manual override controls are typically used for emergency situations or maintenance rather than standard fan operation during regular heating cycles.