NATE Gas Heating Practice Exam 2026 – All-in-One Guide to Master Your Certification!

Direct ignition is the correct choice because it refers to a system where the igniter directly lights the burner without the need for intermediate steps. In a direct ignition system, a spark or flame from the igniter immediately ignites the gas as it flows into the burner, providing quick and reliable ignition. This method is commonly used in modern gas heating systems for its efficiency and reliability.

Intermittent ignition, on the other hand, involves the igniter creating a spark only when there is a call for heat, which then ignites the gas as it is present, but it is not directly lighting the burner in the same immediate manner. Continuous ignition refers to igniting the burner with a flame that is always on, which can create safety and efficiency concerns. Manual ignition requires physical intervention to ignite the burner, which is less common in residential heating applications today. Thus, while other options involve ignition processes, they do not directly light the burner in the same straightforward way that direct ignition does.