The O₂ value is not set with a generic number for all burners. It depends on the burner type, load, combustion chamber, and manufacturer's instructions.
Too low O₂
Can increase the risk of CO formation and unstable combustion.
Too high O₂
Means excessive excess air and increased flue gas losses.
Adjustment across the entire modulation range
In a modulating burner, combustion must be checked at low, medium, and high loads.
Final verification
The correct value is one that falls within the manufacturer's limits, with safe CO levels and a stable flame.
