Where are the tertiary air openings located on a fixed combustion head?

The tertiary air openings play a crucial role in the combustion process of oil burners, especially in promoting efficient burning by mixing additional air with the already atomized oil. These openings are typically found around the outside of the retention head.

This location is significant because it allows the tertiary air to be adequately mixed with the fuel as it enters the combustion zone, enhancing the combustion process. This means that the air can reach the fuel at the right moment, supporting more complete oxidation of the oil and resulting in better combustion efficiency and lower emissions.

When the tertiary air openings are positioned around the retention head, they facilitate a swirl effect that promotes thorough mixing with the fuel and contributes to stable flame characteristics. This design ensures that the combustion is more efficient while maintaining appropriate flame stability.

In contrast, other locations implied by the other options, such as the center of the retention head or beneath the burner, would not effectively promote the necessary mixing of air and fuel for optimal combustion, thus highlighting the importance of the specific location of these openings for burner performance.