Boiler fireside chemicals are used to treat the fireside of boilers and thermic fluid heaters. These ensure proper combustion, reduce clinker formation, increase heat transfer and reduce corrosion. Common boiler furnace treatment chemicals include multifunctional additives, sludge and sediment dispersants, fuel system corrosion inhibitors, antioxidants, and combustion improvers.

Fouling, sooting, clinker formation and other combustion deposits are common in boiler and thermal fluid heater chimneys. The sticky properties of unburned carbon led to the formation of non-combustible solids on the heat transfer surfaces, resulting in poor heat transfer, lower overall boiler efficiency, and increased fuel consumption.