Chapter II.—Steam Heating; Systems of Piping and Steam Supply.
Systems of piping.—The three systems of steam heating as described in Chapter I.—the direct, indirect and direct-indirect radiation are governed by much the same rules in the matter of piping arrangement and steam supply, the two latter requiring only special rules for proportioning the amount of heating surface and for the arrangement of air supply. As regards piping, there are the one-pipe and two-pipe systems, with several varieties and combinations of each; and as regards the steam supply, there are high and low-pressure systems, exhaust systems, gravity systems, vacuum systems—terms more or less indefinite and somewhat mixed in their application.
The essential requisites of a steam-heating system comprise: First, a source of steam supply, which may be either an independent boiler or a heater or tank of some description supplied with exhaust steam from an engine. Second, a system of piping to conduct the steam from the source of supply to the radiators. Third, a series of radiators or radiating surfaces consisting of enclosed spaces in which the steam is condensed by the cooler air of the room on the outside of the surface. Fourth, a system of return pipes through which the water condensed in the radiators is removed; and fifth, a receptacle into which this water is drained.
The second and fourth of these requisites may be either wholly or in part embodied in one, as may also the first and fifth. It might be more briefly stated, therefore, that the prime requisites are only the source of steam supply, the radiating surface and a system of piping connecting them. But even though the supply and the return pipes be embodied in the same system, it is just as necessary that they be so arranged as to dispose of the water of condensation as it is for them to supply steam to the radiator, which fact should never be lost sight of.
One-pipe system.—The simplest possible heating system, therefore, is one which would be known as a one-pipe gravity system,
