Economiser: Economiser is a device used to heat feed water by utilising the heat in the exhaust flue gases before leaving through the chimney. Economiser improves the economy of the steam boiler.

Superheater: Superheater is an important device of a steam generating unit. Its purpose is to increase the temperature of saturated steam without raising its pressure. Superheater is generally an integral part of a boiler, and is placed in the path of hot flue gases from the furnace. The heat, given up by these flue gases, is used in superheating the steam. Such superheaters, which are installed within the boiler, are known as integral superheaters.