Which component is electrically powered by the millivolts produced by a thermocouple?

The gas valve is the component that is electrically powered by the millivolts produced by a thermocouple. A thermocouple generates a small voltage in response to a temperature difference; this voltage is typically measured in millivolts. In gas appliances, the thermocouple is designed to detect the presence of a flame and produce sufficient voltage to keep the gas valve open. When the flame is present, the thermocouple will generate the necessary millivolts to sustain the operation of the gas valve, allowing gas to flow to the burner.

In contrast, other components mentioned, such as the ignition coil, fan motor, and drain pump, require a higher voltage or power source than what a thermocouple can provide. The ignition coil typically requires battery or line voltage to function properly, while fan motors and drain pumps operate on more substantial electrical inputs that are not derived from the low millivolts generated by a thermocouple. Understanding the specific role of each component and their power requirements reinforces the importance of the thermocouple in maintaining safe and effective operation of gas appliances, particularly in ensuring that the gas valve only opens when there's a flame present.