NATE Gas Heating Practice Exam

What type of ignition system commonly uses a thermocouple?

1. Intermittent pilot systems

2. Direct spark ignition systems

3. Glow coil ignition systems

4. Standing pilot ignition systems

The correct answer is: Standing pilot ignition systems

The type of ignition system that commonly uses a thermocouple is the standing pilot ignition system. In this system, the thermocouple serves a critical safety function. It is heated by the flame of the pilot light and generates a small electrical voltage. This voltage keeps the gas valve open while the pilot flame is lit. If the pilot flame goes out, the thermocouple cools down, and the voltage drops, which causes the gas valve to close and stop the flow of gas, preventing potentially dangerous situations. The standing pilot ignition system provides a reliable method of ensuring that gas is only supplied when there's a flame present, highlighting its use of the thermocouple to enhance safety. Other ignition systems mentioned do not typically use a thermocouple in the same way: - Intermittent pilot systems rely on a separate ignition source for the pilot light, which is not continuously lit. - Direct spark ignition systems use an electric spark to ignite the gas directly without the need for a pilot light. - Glow coil ignition systems involve a heating element that glows and ignites the gas, again not requiring a thermocouple for operation. Understanding the role of the thermocouple in standing pilot systems underscores its importance in gas heating safety protocols.