Gas Heat ESCO Practice Exam

The primary cause of burner "flashback" is:

1. high inlet gas pressure

2. improper venting

3. low manifold pressure

4. read-back ignition

The correct answer is: low manifold pressure

"Flashback" in a burner is a dangerous occurence in which a flame starts burning back towards the fuel source, often resulting in an explosion. This is primarily caused by low manifold pressure, as it disrupts the proper balance of fuel and air in the burner. The other options, such as high inlet gas pressure, improper venting, and read-back ignition, may also contribute to burner issues, but they are not the primary cause of "flashback."