What component turns off the blower fan in a heating system?

The limit switch is essential in controlling the operation of the blower fan within a heating system. Its primary function is to monitor the temperature of the heat exchanger. When the temperature rises to a set limit, the limit switch signals the blower fan to turn off, ensuring that the system does not overheat and operates safely. This helps to maintain the efficiency and longevity of the heating system.

The thermostat plays a different role by regulating the overall temperature within the space by starting or stopping the heating process based on the desired setpoint. The transformer is responsible for supplying power to various components within the heating system, while the pressure switch monitors the pressure levels in systems like gas and oil furnaces to prevent unsafe conditions. However, none of these components specifically control when the blower fan turns off; that responsibility lies with the limit switch.