Excess Air Calculator
How Much Extra Air a Burner Is Actually Running
Excess air is the air supplied beyond the stoichiometric requirement, expressed as a percentage. It's one of the first numbers checked during a combustion tune-up, since too little starves the flame of oxygen and too much wastes energy heating unnecessary air.
The Formula
Excess Air % = ((Actual Air − Theoretical Air) / Theoretical Air) × 100
Worked Example
A burner supplied with 15 kg of air against a theoretical requirement of 12.5 kg:
Excess Air % = ((15 − 12.5) / 12.5) × 100 = 20%
How to Use This Calculator
- Enter the Actual Air supplied to the burner.
- Enter the Theoretical (stoichiometric) Air required.
- Select Calculate to see the excess air percentage.
Related Calculations
Find the theoretical air this compares against with the Stoichiometric Air Requirement Calculator, or check the resulting O2 in flue gas with the Flue Gas Oxygen Calculator.