NATE Gas Heating Practice Exam

What is indicated by a steady yellow flame in a gas burner?

1. Efficient combustion

2. Sufficient airflow

3. Inadequate air supply

4. High combustion pressure

The correct answer is: Inadequate air supply

A steady yellow flame in a gas burner is an indication of inadequate air supply during combustion. When a gas burner is functioning properly with sufficient airflow, the flame typically appears blue. A yellow flame suggests that there is not enough air mixing with the gas, which can lead to incomplete combustion. This can produce carbon monoxide and other harmful emissions, and it often signifies that the burner is not operating efficiently. In contexts where the flame is not blue, such as in situations requiring high combustion pressure and sufficient airflow, one would expect a different flame color. Thus, monitoring the color of the flame is crucial for diagnosing the efficiency of a gas burner, as it can impact both safety and performance. Overall, the presence of a steady yellow flame should prompt further investigation into the burner setup to ensure proper combustion.