What is secondary air?

Secondary air refers to the air that surrounds the burner, which is critical for the efficient operation of combustion processes. It plays an essential role in ensuring that there is enough oxygen available for complete combustion, helping to improve the burner’s efficiency and performance. As the burner operates, this surrounding air mixes with the fuel, allowing for a more thorough and effective burning process.

In the context of this question, the focus is on the air that is available in the environment around the burner, rather than air that is expelled after combustion or specifically introduced through the burner venturi. Additionally, while cooling air is important in maintaining equipment health, it serves a different function compared to secondary air used in combustion. Recognizing the importance of the surrounding air in relation to combustion efficiency is key in understanding why this choice is the correct one.