What generates heat in a boiler?

The generation of heat in a boiler primarily occurs through the combustion of a fuel. When fuel (such as natural gas, oil, or coal) is burned, it releases heat energy as a byproduct of the chemical reaction. This heat is then transferred to the water or steam within the boiler, raising its temperature and allowing the system to perform tasks such as heating a building or generating power.

While other methods of generating heat may exist, combustion is the most common means in traditional boiler systems. Electrical resistance can produce heat but is not the primary method for large-scale boilers. Renewable energy sources can also generate heat, but they need to be specified to understand their effectiveness in a particular system. Circulating water through a boiler is crucial for heat transfer and efficiency but does not itself generate heat; it merely serves to transport heat away from the combustion area to where it is needed. Thus, combustion stands out as the central process that drives heat generation in most boilers.