In a gas water heater, what is the function of a thermocouple?

In a gas water heater, the thermocouple serves as a small electric generator. It converts heat energy from the pilot flame into a small electrical voltage. This voltage is used to keep the gas valve open, allowing gas to flow to the burner when the pilot light is lit. If the pilot light goes out, the thermocouple cools and the generated voltage decreases, causing the gas valve to close and preventing gas from leaking into the environment. This safety feature helps ensure that the water heater operates efficiently and reduces the risk of gas leaks, which could be hazardous. Therefore, the thermocouple plays a crucial role in the overall operation and safety of a gas water heater.