Excess air is necessary for safe and complete combustion, but an excessive amount reduces energy efficiency.
Why excess air is needed
In actual combustion, mixing is not perfect, therefore some excess air is required to limit CO.
What happens when it is excessive
A larger mass of air is heated and expelled through the flue gases, increasing losses.
Relationship with O₂
Higher O₂ in the flue gas usually means more excess air.
Adjustment goal
The correct range is the one that maintains safe CO, a stable flame, and good efficiency according to the burner manual.
