S32 -- Boilers (I-P)

Excluding special and unusual fluids, materials, and methods, a boiler is a cast-iron, carbon or stainless steel, aluminum, or copper pressure vessel heat exchanger designed to (1) burn fossil fuels (or use electric current) and (2) transfer the released heat to water (in water boilers) or to water and steam (in steam boilers). Boiler heating surface is the area of fluid-backed surface exposed to the products of combustion, or the fire-side surface. Various manufacturers define allowable heat transfer rates in terms of heating surface based on their specific boiler design and material limitations. Boiler designs provide for connections to a piping system, which delivers heated fluid to the point of use and returns the cooled fluid to the boiler. In the 2024 ASHRAE Handbook -- HVAC Systems and Equipment, Chapters 6, 11, 12, 13, and 15 cover applications of heating boilers, and Chapter 7 discusses cogeneration, which may require boilers. Classifications Selection Parameters Efficiency: Input and Output Ratings Performance Codes and Standards Sizing Burner Types Boiler Controls Flame Safeguard Controls