Final answer:
An intermittent pilot is a type of ignition system used in gas-fired appliances such as furnaces, boilers, and water heaters. Its function is to ignite the main burner and ensure that it remains lit during operation. Option D, 'Stay on during the main burner operation,' best describes the function of an intermittent pilot. It provides a continuous source of ignition throughout the burner's operation, allowing for efficient and reliable heating.
Step-by-step explanation:
The function of an intermittent pilot is to ignite the main burner and then shut off after the main burner has been lit. Unlike a continuous pilot, which stays lit at all times, an intermittent pilot is designed to reduce energy waste by operating only when the main burner needs to be ignited. When the thermostat calls for heat, the intermittent pilot lights the main burner and once the flame is established and confirmed, typically by a thermocouple or flame sensor, the pilot shuts off until it is needed again to reignite the main burner.