Page:Steam heating and ventilation (IA steamheatingvent00monrrich).pdf/29

 valve. These valves, one of which is represented by Figure 5 C, are of such construction that they can be set for any desired difference between the high and low-pressure sides. The reducing valve must always be set for a pressure somewhat lower than that at which the back-pressure valve opens, as otherwise some live steam from the reducing valve might pass through the back-pressure valve to the atmosphere and thus be wasted.

Steam Heating and Ventilation - Figure 5c.png

5C

Steam Heating and Ventilation - Figure 6.png

Figure 6—Exhaust Steam-Heating Supply Connections.

Figure 7 shows an arrangement with a pressure heater which is much employed in steam-heating systems. The exhaust steam enters the bottom of the heater and goes out at the top. The connection is also provided with a by-pass so arranged that in case it is necessary to shut out the heater for repairs or cleaning, the valve B in the by-pass may be opened and the valves A and C closed, so that the steam will pass around the heater. In ordinary use the valve B in the by-pass is closed and A and C opened. The arrangement of the supply to the heating system, which is connected to the outlet of the heater, and the back-pressure valve on the free exhaust, is the same as indicated in Figure 6. The main return pipe is run into a cylindrical receiving tank, from which the water is pumped through the heater. Attached, to the receiving tank is an automatic pump governor, which, by means of a float operating on the steam