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the stop-and-waste cock e, the hot and cold water supply to the fixtures on the second floor being controlled by similar stop-cocks in the circulation pipes.
A series of waterbacks W. B. may be connected to a boiler, as shown in Fig. 4, so as to secure a positive and efficient circu. lation between each waterback and the boiler. The arrows show the direction of the currents. To prevent the waterbacks farthest from the boiler from being short-circuited by those nearest the boiler, the pipes are reduced in size, as indicated. In case the side tapping of the boiler is too small, or in case the ranges are set too far apart, and the proper head for circulation cannot be obtained, hot-water flow pipes may be connected to the top of the boiler as shown by the dotted
lines in the illustration; or, the boiler may be raised so that a satisfactory head may be secured for a connection to the side opening.
Boiler Connections for Heating.-Connections may be made as shown in Fig. 5 for utilizing the water heated by the kitchen fire in warming rooms located above the range boiler. The heated water ascends in pipe a and enters the side of the boiler, where it rises to the top of the boiler because it is lighter than the colder water. Cold water from the bottom of the boiler flows through b to replace the heated water that leaves the range. The hot water at the top of the boiler flows up the pipe c and enters the radiator through the radiator valve shown at the right. It then passes through the radiator,
gives off heat to the room, and when cooled descends in the pipe d and returns to the boiler to be reheated. An air vent placed at c will automatically allow air to escape from the radiator. If it cannot thus escape it will accumulate and stop circulation. The pipes c and d must be graded so as to avoid pockets that would retain air.
Range boiler connections may be made as shown in Fig. 6 for heating the water in winter by means of a hot-air furnace heating coil a and in summer by means of a gas heater b, a radiator c being used to supply heat to the kitchen. The water heater in the furnace must be set and maintained dead level in order to produce good results. By connecting the hot-water pipe from the furnace water heater to the side of the boiler d, two distinctly separate circuits are secured, neither one depending on the other for circulation except at the nipple e, which can be made 1 in. The connections between the furnace coil and the branches to the radiator and range
boiler should be 1" pipe, as shown, the supply and return branches to the radiator being 1 in., and the supply branch to the range boiler in. The arrows indicate the direc tion of the circulation of the water through the boiler, furnace, and gas heater. It is advisable to run a hot-water branch from the highest point to supply a wash basin upstairs, so that the air that accumulates at the highest point of the piping system may be drawn off at the basin.
Hot-Water Supply to Fixtures Below Range Boiler.-To pipe a
building so that the hot water can be drawn instantly at fixtures located at a lower level than that of the boiler, it is necessary to form a loop by running the hot-water pipe up as high as possible before descending to supply the lowest fixtures, as shown in Fig. 7. The laundry tubs are located
Hot Water Outlet
in the basement and the system is supplied from a tank in the attic. The hot-water distributing pipe forms a loop, the flow pipe of which connects to the top of the boiler, and the return end to the bottom. A relief pipe is located at a, the highest point of the loop. This allows the air to escape
from the loop, which would otherwise become air-locked. A stop-cock is placed at the base of the relief pipe, as shown, which may, if necessary, be checked down to a very small opening to prevent air from being sucked into the cock while the hot water is being drawn at the fixtures. A checkvalve fitted with a very light swinging valve is attached to
the return pipe of the loop as shov to prevent cold water in the bottom of the boiler from being drawn at the hot-water faucets of the tubs.
Stop-Cock Arrangement.-The symmetrical arrangement of stop-cocks is one of the distinguishing characteristics of an
expert plumber or pipe fitter. The low-grade mechanic places the stop-cocks anywhere without reference to a neat appearance of the work. The skilled mechanic, who is a neat, tidy workman, arranges them symmetrically and with taste. Fig. 8 shows a neat job in which a is the cold supply from the street; b, the boiler tube; c, hot water to laundry; d, a waste pipe from the stop-cocks on the pipes that supply the fixtures upstairs, and the safety valve e.
Hot-Water Supply Tanks. These are cylindrical in form and are made plain or galvanized, and with or without steam coils. The table "Capacity of Hot-Water Supply Tanks" gives some of the common stock sizes of tanks.
Hot-water supply tanks used where a large quantity of hot water is required are usually provided with steam coils, as shown in Fig. 9. The coil is made from pipes and fittings; steam enters the coil through the pipe a and passes into a manifold b, whence it passes through the pipes c, c
and return bends d, d into the manifold e and leaves through the pipe f. The number of coils to be used depends on the amount of heating surface desired. The pipes a and ƒ screw into large bushings g, g threaded outside to fit a tapped hole