What does the fan and limit control on a warm air furnace manage?

The fan and limit control on a warm air furnace plays a crucial role in managing the operation of the burner in relation to set temperatures. This control is designed to ensure that the furnace operates efficiently and safely by regulating both the temperature of the air being heated and the periods of operation for the burner.

Specifically, the limit aspect of the control monitors the temperature of the air in the heat exchanger or the environment. When the desired temperature is reached, the limit control will typically shut off the burner to prevent overheating, ensuring that the temperature remains at a comfortable and safe level. Conversely, when the air temperature drops below a specific threshold, the burner will activate again to provide heat.

In this context, the fan component of the control also activates the blower fan to circulate warm air throughout the living space once the burner is operational. This ensures that the warm air generated by the furnace is effectively distributed.

By managing these operations based on temperature settings, the fan and limit control helps maintain the overall comfort and safety of the heating system while also promoting efficient energy usage.