provide steel rods long enough to use on long-range connections, and if provided, the plumber would find them awkward to carry. In the case of long connections, the rods may be built out as far as possible from the range and from the boiler, and the measurement for the long run of pipe taken in the usual manner between the two last measuring points. The use of this device will be found to save much annoyance to both workman and customer. In the event of wrong or incomplete measurements, it often becomes necessary for the plumber to return to the shop to get out Bonge Boiler корде חוחן FIG 283. Use of Center-Meter, a Device for Taking Range Connection Measurements. additional pipe, which is usually much disliked by the customer. The center-meter, if used properly, cannot make these mistakes, even in the hands of an unskilled person. In the running of hot-water pipes, there is often opportunity for the exercise of judgment. For instance, in Fig. 284 are shown two methods of running such pipes, one of them a correct method and the other incorrect. The tendency of hot water is always to rise. Therefore, the practice of carrying the pipe from the top of the boiler directly down to fixtures on the same floor as the boiler, and to fixtures below, does not afford a natural path for the hot water. It means that the hot water must take a downward and unnatural direction, rather than an upward, natural direction. This practice of running hot-water pipes is, nevertheless, a common one. In the instance of Fig. 284, where a connection is taken from the high point, to supply fixtures above the boiler, any accumulation of air will rise in this connection, and escape through the highest hot-water faucet, whenever it is opened. If it were not for this connection, however, there would be danger of the accumulation of air at the high point, which would interfere with the circulation, and very often cause the circulation to cease entirely. The collection of air in high points in the hot-water pipes, is an evil which must always be avoided, as it is the means of endless trouble in both supply and heating systems. The correct method, shown in Fig. 284, consists in carrying the flow pipe from the boiler horizontally above the boiler, and dropping down with branches to the several fixtures. This method provides the more natural path for the hot water, and is in all ways the more satisfactory method of the two. Ordinarily the hot- and cold-water pipes are run parallel and close together. When so run, the hotwater pipe should be carried above the cold water. The reason for this is that as heat rises, the heat from the hot-water pipe will have less effect upon the cold-water pipe, if run above it. CHAPTER XXIV CIRCULATING PIPES IN the running of hot-water piping on ordinary work the supply lines to fixtures are run as directly as possible to them, the different branches ending at the fixtures. This method is shown FIG. 286.-Circulation Applied to a Single Fixture. in Fig. 285. There is great objection to this course many times, and for the following reason. Although the water in the piping is supposed to be hot, it cools very fast under certain conditions, and especially in branches at a distance from the boiler. In many |