Heating system such as furnace and boiler are frequently carried out to generate thermal energy for many applications. In a pasteurized milk plant, heat is mainly required to kill virus and bacteria in raw milk. This means that the hot water supplied to this process should be over 72 C [1]. Furthermore, the heat is also utilized to sterilize piping systems and equipments before and after production [2]. Hence, a boiler is mostly employed to supply ther- mal energy in terms of steam or hot water for these processes. Generally, it has an inefficient consumption in energy owing to heat loss as waste heat in term of an exhaust gas. The waste heat in the exhaust gas is able to be recovered by many techniques: pre- heating the boiler’s feed water by the economizer, preheating the