What is a primary cause of burner "flashback"?

A primary cause of burner "flashback" is low manifold pressure. When the manifold pressure is too low, it can prevent the proper mixing of gas and air, leading to the flame not being established correctly at the burner ports. Instead, the gas can ignite at the burner tubing before it properly reaches the burner assembly. This improper ignition can lead to a "flashback," where the flame attempts to travel back into the gas supply line instead of burning at the intended location.

Low manifold pressure results in an imbalance in the combustion process, making it difficult for the burner to maintain stable and safe combustion conditions. This can not only lead to flashback but also affect overall heating efficiency and safety. Proper manifold pressure is essential for stable burner operation, effective flame retention, and preventing dangerous conditions such as flashback.