NATE Gas Heating Practice Exam

What characterizes an intermittent ignition system?

1. It lights the burner continuously

2. It lights the pilot only on a call for heat

3. It uses a thermocouple for ignition

4. It is the most reliable ignition method

The correct answer is: It lights the pilot only on a call for heat

An intermittent ignition system is designed to enhance efficiency and safety by lighting the burner only when there is a call for heat. This means it activates only when there is a demand for warmth, such as when a thermostat signals that the temperature has dropped below the desired level. By only igniting the burner as needed, this system avoids wasting gas when heating is not required, making it an energy-efficient choice. The pilot is activated in response to this demand, ensuring that there's a flame present only when it is necessary for generating heat. This characteristic distinguishes intermittent ignition systems from continuous systems, which keep the burner lit at all times, regardless of whether heat is needed. This on-demand operation helps to reduce both fuel consumption and the potential for gas buildup in the system during periods of inactivity. In terms of reliability, while intermittent ignition systems are effective, they do not necessarily represent the most reliable method when compared to other ignition systems like power vent or hot surface ignition. Additionally, while thermocouples are involved in safety and monitoring functions in some heating systems, they are not inherently used for ignition in intermittent systems. This highlights how option B accurately represents the defining feature of intermittent ignition systems.