High O₂ or excess air: why burner efficiency drops

Very high O₂ in flue gas usually means more air is passing through than combustion requires. This increases flue gas losses and reduces efficiency.

Possible causes

Incorrect damper position, poor servomotor adjustment, air leakage, or excessive draft can lead to excess air.

Relationship with flue gas temperature

The more air that is heated and exhausted through the chimney, the higher the energy losses.

Do not reduce air arbitrarily

Adjustment should be performed in conjunction with CO measurement and flame stability checks. Excessive air reduction can lead to incomplete combustion.

Curve verification

The correct ratio must be verified throughout the entire modulation range and not just at a single load point.