As it showed from the name, our bi drum boiler comprises quantities of cylinders through which hot gasses are passed. These hot gas tubes are drenched into the water, in a shut vessel. Entirely shoot tube heater contains water, through which hot cylinders are passed. These fire tubes or hot gas tubes warmed up the water and convert the water into steam and the steam stays in the same vessel. As the water and steam both are in the same vessel, our bi drum boiler cannot deliver steam at high weight.