What is the main function of the fan and limit switch in a furnace?

The fan and limit switch in a furnace primarily controls the air temperature by regulating when the fan should turn on and off based on the temperature of the air within the system. When the furnace heats the air, the limit switch monitors the temperature. Once the air reaches a certain temperature, the limit switch activates the fan to circulate the warm air throughout the home. Conversely, it can also turn off the fan when the air cools down to prevent unnecessary energy consumption and maintain comfortable indoor conditions.

This functionality is crucial for ensuring that the heating system operates efficiently and safely. In scenarios where the temperature exceeds safe operating limits, the limit switch can protect the furnace from overheating by shutting off the burner and possibly the fan as well, contributing to both safety and efficiency in heating an environment.