A thermocouple is a small but fundamental part of many gas-powered appliances, such as water heaters, and stoves. It detects temperature changes and controls the flow of gas based on whether a flame is present. This mechanism prevents gas leaks, protecting both the appliance and the home

When two different metals are joined together and exposed to a temperature difference, they produce a small electric current. In appliances, this current keeps the gas valve open while the flame is active. If the flame goes out, the thermocouple cools, cutting off the current and automatically closing the gas valve to prevent leaks.