What is referred to as the boiler heating surface?

The boiler heating surface is defined as the area where water is heated directly by the heat generated from combustion gases. This includes surfaces that are in contact with water, allowing efficient transfer of heat to convert water into steam. The efficiency of the boiler and its ability to produce steam effectively depend on the size and quality of this heating surface.

The other areas mentioned, such as where fuel is atomized or where combustion gases pass through, serve different functions in the overall operation of the boiler but do not contribute directly to the heating of water. Similarly, the outer surface of the boiler relates more to safety and insulation than to the actual heating process. Understanding the role of the heating surface is crucial for efficient boiler operation and ensuring optimal steam production.