pipe for the radiator is taken from the range connection and carried to the radiator, which should be provided with an air valve, the return being taken into the return of the range connection. Valves are placed on the flow pipes to boiler and to radiator, the latter being located at the radiator if more desirable. The use of Boiler Supply Not to Fixtures, Wall Coil Water Front FIG. 329.-Wall Coil and Fixtures of Apartment Supplied by Horizontal Boiler. these valves allows the heat of the range to be thrown either to the boiler or to the radiator, as the case may be. For instance, if the demand for hot water is heavy, the radiator may be turned off for the time being. It must be seen to, however, that each of the two valves is not closed at the same time. In this connection it may be stated that valves should be used to as small an extent as possible on hot-water supply work, as their wrong use is sometimes attended with serious consequences. Small rooms, such as bath rooms, small bedrooms, etc., which FIG. 330.-Heating Radiator by Stove Coil on Floor Below Stove. would require only a few feet of radiation may often be successfully heated in this way. Another familiar problem is that requiring the heating of a radiator or coil on the same floor as the range and boiler. Such an arrangement is shown in Fig. 329. To heat the coil, the flow pipe from the boiler is carried up and then directly down into the top of the coil or radiator, a valve being placed on the pipe. The return is connected from the bottom of the coil or radiator into the return of the range connection. It is necessary to relieve this connection of air by means of an air valve at its high point. In the case of a supply system under tank pressure, the expansion pipe would perform this duty. A more uncommon connection is shown in Fig. 330, in which a radiator is to be heated by a stove coil, without use of the hotwater supply system, and with the radiator on the floor below the stove. This radiator may be heated by running the flow pipe from the stove as high as possible, and connecting it into an expansion tank provided with an overflow. From the bottom of the expansion tank a feed pipe into the bottom of the radiator is taken, and the return end of the radiator connected back to the return of the coil. The water in the tank must stand above the opening of the flow pipe into it, and should be turned on from time to time to make up for any loss that may have been sustained. The heating of a radiator under these adverse conditions is due to the weight of water rather than to circulation, and can be made to give fair results with a good heating surface in the stove. The range boiler is very often fed from two or more different sources, such, for instance, as kitchen range, furnace coil, laundry heaters, gas ranges, etc. Such a combination is seen in Fig. 331 in which the boiler is heated by a coal range, gas range, and furnace coil. Either one of these sources of heat may be used independently of the others. The connections of the flow pipes from the two ranges are so made as to produce quick heating of the boiler, while the flow pipe from the furnace coil enters the boiler at the side in the usual manner. The boiler shown in Fig. 331 is of the three-tube pattern, which allows the circulating pipe to be carried to the bottom of the boiler. CHAPTER XXIX THEORY FOR THE PLUMBER In order to be successful in his work, the plumber of to-day must have at his command not only a knowledge of the practical requirements of his trade, but also a knowledge of the theory that underlies it. Every action that takes place in the drainage or supply system depends in some way upon some natural law, as also the action of various devices employed on the plumbing system. It will be evident then that a knowledge of certain of these actions, and the laws governing them, is necessary to the plumber, in order that he may be able to understand and solve the various problems that are constantly arising in his work. Possibly to a greater extent than in almost any other trade the efficiency of the plumber consists largely in his ability to avoid trouble and to successfully get out of trouble that he already finds himself in. Of the various phenomena to be considered, that of atmospheric pressure is perhaps of first importance. The atmosphere may be considered as a very light fluid, of certain depth, surrounding the earth. Although of small density, the weight of the atmosphere, which is computed to be about 45 miles in depth at the sea level, is very appreciable. Experiment has demonstrated that at sea level, the pressure of the atmosphere amounts to about 14.7 pounds per square inch. In ordinary computations, atmospheric pressure is considered as 15 pounds per square inch. Now in a square foot of surface, there are 144 square inches. Therefore, the pressure of the atmosphere on each square foot amounts to about 2160 pounds, or over a ton. This will serve to indicate what an immense pressure the atmosphere is capable of exerting. That this pressure does not result in crushing everything that it comes in contact with, is due to the fact that the same pressure is exerted from all sides, thus equalizing the effect. Thus in the case of the human body, atmospheric pressure is exerted from with |