Combustion Fundamentals1 / 10
The Combustion Process
Fuel, air, and ignition — stoichiometric and excess air.
10 min read · Jacob Willis, Net Zero Lead · Last reviewed July 2026
A boiler is a heat-exchange system that converts chemical energy in fuel into heat in water or steam. Understanding combustion, the chemical reaction that releases that energy, is the key to understanding where boiler efficiency is lost and how to recover it.
In this lesson
- 01The combustion reaction
- 02Excess air: the practical necessity
- 03Measuring combustion quality: O₂ and CO
- 04The energy balance
- 05Condensing boilers: capturing latent heat
- 06Sources and further reading