Note

An illustration of a reverse attachment, which is sometimes used in connection with the double boiler by steam, is given in Figures 95 and 96, and its functions explained.

The reverse attachment alluded to in the note on the preceding page is illustrated in Figure 95. In order that the following explanation may be more readily understood, it will be well to refer to the illustration of the double-boiler system on page 147. In most houses where this system is adopted, it is found that on the second floor the flow of water from the street-main is intermittent - i. e., at times water is not obtainable, by reason of an insufficient pressure in the street-mains; at other times the pressure is ample to supply that floor.

In such situations, therefore, the reverse cock is placed on the branch-pipes from both the tank and street-main hot and cold water pipes. This is put under a wash-basin or in some accessible place, so that when the supply from the main fails, a supply from the tank can be obtained by a turn of the lever, which, when closing the two stop-cocks on the supply-pipe from the street, opens the stop-cocks on the hot and cold supply - pipes from the tank. Of course, when these are open the water used is that which has to be pumped; consequently they are only kept open when the street-pressure fails to reach that floor. By reference to the sketch, it will be noticed that the pipes all come through the lead safe, which indicates its location under a wash-basin; of course a plumber will understand the various ways that the branches can be run so that they may come up through the safe as shown. It will also be noticed that I refer to this reverse attachment as being placed on the branches. I have no positive knowledge of the fact, but it is asserted that in some instances plumbers have connected one or more of the cocks in this attachment to the main pipes, either to save pipe or because it was a little more convenient. By an examination of the double-boiler cut it will be made evident that this would be a dangerous proceeding, because the closing of one of these cocks would close the expansion-pipe that extends from the boiler over the tank, with its end open to permit the escape of steam, and would result in straining the boiler, if not the more serious casualty of an explosion.

Figure 95.

Figure 96 shows the usual arrangement before the reverse attachment was made, which, as will be seen, consists in placing separate stopcocks on each branch from street and tank supply. This is also shown located under a washbasin. It is customary to put a label on each stopcock to indicate its particular use.

Occasionally two independent boilers are used in place of a double boiler, to secure the same results; but in most kitchens a convenient space to locate them cannot be found, although when such an arrangement is practicable, each boiler can be larger - that is to say, from 50 to 80 gallons each, which would be equivalent to an 120 to 160 gallon double boiler, whereas the sizes most frequently used are from 80 to 100 gallons capacity. As a general thing where double boilers are used, an independent single boiler of from 40 to 50 gallons capacity is provided for the laundry, and placed alongside the laundry range, and connected with its water-back. This is intended to supply hot water only for laundry purposes.

In the reference to hot-water boilers placed in the laundry of a private dwelling, mentioned above, I simply described the custom in New York City. It may be well to explain that in the New England States, or in the vicinity of Boston, water for laundry purposes is often heated in an open-top copper boiler, which is set in brick-work alongside of a set of soapstone wash-trays. The fire is built under this boiler, a draw-off cock is placed on it, and the hot water is drawn off and poured into the tubs as required.

Figure 96.

I have, in the preceding pages, referred to the various methods of fitting up bath-boilers in this country and in Europe with which I am acquainted, and I shall now conclude the chapter on boilers by a few suggestions that occur in considering the conditions of their use.

In this city, where the building of flats has become so general, the question is frequently raised whether it is better to have a bath-boiler for each flat in each kitchen, connected with the water-back in the range, or whether the hot water should be supplied to each flat from some central source - as, for instance, a large boiler in the basement. In intelligently deciding this point various things must be considered. In the smaller flats, where steam is not required to run elevators, and is only needed to heat the halls in the winter time, it is the practice, and is, no doubt, more economical for the owner of the building to provide a boiler for each flat, as the fuel required by the family for cooking will also heat what water is needed, and this, of course, involves no expense to the landlord. As usually fitted up in flats, copper boilers are apt to collapse, because of the liability of the water being syphoned out of those on the upper floors when it is drawn off at a lower point. This could be guarded against, but specifications do not require the precautions to be taken, and the cost would deter any plumber from doing it in contract work, consequently galvanized-iron boilers are now almost universally used in such situations, as they are sufficiently strong to withstand the atmospheric pressure in the event of there being a vacuum formed inside of them by the withdrawal of their contents. One other objection is the fact that the boiler in the small kitchen of a flat adds to the heat of this, as well as of the adjoining rooms, and in hot weather this is sometimes an inconvenience.

In hotels and first-class flats water is heated for use throughout the building by placing a coil of brass or iron pipe inside a large wrought-iron tank, and heating the water by passing steam through this coil. Brass pipe is considered for this purpose to make the best job; but iron is most frequently used, although copper mains - such as are used in stills - are sometimes adopted.

Exhaust steam is sometimes availed of for this purpose, and is the most economical, although I think, as a general thing, live steam is taken from the boiler required to furnish the power to run elevators, etc. These hot-water tanks are supplied with water from the tank on the top floor; connections are also made to supply them from the street-main, with a check-valve on this pipe to prevent the tank-water from running back to the main, but to permit the street-pressure to supply the boiler when there is no water in the upper tank.

In these articles on hot-water boilers it seems proper to refer to the wearing out of hot-water pipes, which occurs with the most frequency near the range or between the boiler and the range. This is generally due, in the case of lead pipe, to impeded circulation or too much heating capacity in the water-back, there being considerable difference in this respect with the various makers of ranges. In some cases, where the water-back was large, I have known of a piece of wrought-iron pipe, this shape (⊃), to be substituted for a large cast-iron water-back. This will burn out in time, but is capable of making a great deal of hot water. Where lead is used for the hot-water pipe, it has been the practice, in first-class work, to have a copper pipe brazed on to the coupling of the boiler and of the water-back, and in order that the coppersmith could get the exact dimensions and the proper direction for this connecting piece, a lead-pipe connection was made to serve as a model; and to insure an absolutely tight and strong joint where the pipe was brazed to the couplings, a good soldered joint was wiped over it. Connections made as here described have been found much more durable than with the ordinary lead pipe.

Vacuum-valves have been largely sold for use on the hot-water pipes of copper boilers, to supply air and prevent a collapse. Some are made to screw into a spud attached to the boiler for this especial purpose. I have never considered them reliable, and I think the experience of plumbers has been that the valve, not being in constant use, is liable to stick to its seat and become inoperative when most needed. An expansion-pipe, as before explained, with its open end above the source of the supply to the boiler, which should be a tank in the upper part of the house, is, in my judgment, the only safe plan.