How does a thermocouple work in gas appliances?

A thermocouple functions by generating a small electrical voltage in response to temperature differentials, which makes it a vital safety feature in gas appliances equipped with pilot lights. When the pilot light is lit, the heat generated by the flame warms the thermocouple, causing it to create a voltage. This voltage activates a solenoid within the gas valve, keeping it open and allowing gas to flow to the burner.

If the pilot light goes out, the thermocouple cools down, resulting in a drop in the generated voltage. This drop triggers the solenoid to close the gas valve, stopping the flow of gas and preventing potential leaks or dangerous situations. Thus, the thermocouple serves as a critical safety device that ensures gas is only supplied when the pilot light is operational, effectively protecting against gas buildup and associated hazards.

Understanding this mechanism emphasizes the importance of the thermocouple in ensuring safe operation of gas appliances, distinguishing it clearly from other functionalities such as igniting the gas or regulating pressure and temperature.