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The number of different heating systems is almost unlimited. Various systems of heating are being used at the present day. They are: direct, indirect, water heating systems, steam heating systems and so on. A direct system is that in which the fuel is consumed in the room. It is being used for intermittent heating, or for heating isolated rooms. An indirect system is that in which the fuel is consumed outside the room. In this system the heat is being conveyed to the room by a medium such as steam or hot water. Indirect system is being used for the continuous heating of a number of rooms or large buildings. It begins from one central source and that’s why it is named Central Heating. Steam heating systems are classified according to the following features: piping arrangement, pressure or vacuum conditions, obtained in operation and method of returning condensate to the boiler. A steam heating system is known as a one-pipingandtwo-pipesystem. Inone-pipingsystem a single main supplies steam to the heating unit and conveys condensate from it. Intwo-pipesystem each heating unit is being provided with two piping connections. Steam and condensate flow in separate branches. Steam heating systems are classified as high pressure, low pressure (vapour) and vacuum systems. This classification depends on the pressure conditions under which the system is designed to operate. The system is known as a gravity return system. Condensate is returned to the boiler by gravity. All heating units are being elevated above the water line of the boiler.