In some cases it is very desirable that brickwork should be avoided; a vertical type of boiler should then be used, such, for instance, as that shown in Fig. 547. This type has the very important advantage that it possesses a central fuel-hopper, so that a considerable charge of coal can be put on at once, and the boiler will not require so much attention. It" is arranged with a ring of vertical fine-tabes, through which the products of combustion rise, and also with a second ring of tubes, through which they descend; these tubes are surrounded by the water, so that an efficient heating-surface is obtained. A good steam-space is also provided, which is important, as it is very desirable that dry steam should be obtained.



Fig. 548 - View, section, and Plan of the "Caloric " Boiler for Steaming-heating.

A neat little boiler, which, however, requires brick-setting, is shown in Fig. 548.

This has also a central hopper for receiving the fuel, and therefore will require leas attention than if the door on a level with the grate were the sole means of stoking. The products of combustion pass up into the water-space in an annulus before going out to the chimney-stack. One outlet-pipe is provided, and one inlet, although two inlets are shown in the illustrations.

Low Pressure Steam Heating 400143Fig. 549.   section and Plan of Lumby, son, and Wood's Patent   Pioneer  Boiler.

Fig. 549. - section and Plan of Lumby, son, and Wood's Patent " Pioneer" Boiler.

A boiler of somewhat novel construction is shown in figs. 549 and 550, and is known as the "Pioneer" independent boiler. As will be gathered from the illustrations, it consists of outer and inner cases, and of a series of water-tubes. It is made in suet varying in height from 54 to 82 inches; the smallest size is said to be capable of heating 600 square feet of actual radiating surface, and the largest 1750 square feet These boilers are made of Siemens mild steel plates welded together, and are fitted with safety-valve, water-gauge, and prssure-gauge. It may be remarked in passing that a very similar boiler is made for low-pressure hot-water heating, but in this case the water of course fills the boilet completely.

Every boiler, no matter how small, should be provided with the following fillings: Two safety valves (one of the lever type, loaded so as to blow off at. say, 5 lbs., and the other a dead-weight safety-valve which cannot be tampered with, and loaded to, say, 7 lbs. pressure), a reliable pressure-gauge of the Bourdon type, made by some well known maker, and a water-gauge, so that the level of the water in the boiler may be easily observed. There should be a mark upon the gauge, or a brass pointer should be fixed upon the boiler-casing, showing the proper working-level of the water, so that the attendant may observe instantly if the water is getting too low. If this were to occur the crown of the firebox would become dry, and might become red hot. Fusible plugs are often inserted to guard against such an occurrence, as the fusible metal contained in them melts out, and the water pours in upon the fire and extinguishes it.

Messrs. Korting Bros, have a special system of low-pressure steam-heating, which certainly deserves notice. The boiler itself is represented in figs. 517 and 518, pages 120 and 121. This system differs considerably in many points from the usual methods of heating by steam. Fig. 551 is an illustration of the general arrangement. G is the low-pressure steam-boiler, t the fuel-hopper and patent furnace, s the safety-pipe, v v the steam-distribution pipes, ss the coils or radiators to the rooms, v v the steam-admission valves, c c' v the return-pipes for condensed water, a the air-pipe, W the syphon-pipe between the air and water vessels, R the syphon water-vessel with air-pipe, and r' the syphon air-vessel. The steam-generator, or boiler, which has already been described in detail upon page 121, is placed in the basement of the building, in as central a position as can be conveniently arranged. The steam generated, at a pressure of 1 to 5 lbs. per square inch, is conveyed by the steam-distribution pipes v v to the radiators s s. The radiators, which are filled with air from which most of the oxygen has been absorbed, are placed upon the various floors, so that they stand as far as passible in series one above the other, and, where this can be arranged, they have joint condensed-water return-pipes c c, falling vertically to the basement, where they are collected into a common main return-pipe at the floor-level. A further connection is made from each radiator to the air-collect ing pipe a, which is carried under the ceiling of the basement, and connected to the air-vessel r', and also by means of a "drain-pipe" c, to the main return-pipe on the floor. The air-vessel r' is joined by the syphon-pipe w to the water-vessel r, and as this latter has a pipe open to the atmosphere, it is in consequence always under atmospheric pressure. The capacity of each of the two A, air-pipe. e e e. return-pipes lor condensed water: G, low-pressure steam-boiler; R, syphon water-vessel with air-pipe; R', syphon air-vessel. s. safety pipe; a, coils or radiators in the rooms; T, fuel-hopper and patent furnace; v, steam-admission valves; V . steam distribution pipes; W. syphon-pipe between air and water vessels.

Fig 550   View of Lumby. Son. and Wood's Patent   Ploneer  Boiler

Fig 550 - View of Lumby. Son. and Wood's Patent " Ploneer" Boiler.

Fig 551.   General Arrangements of Kortlng's Low presure Steam Apparatus.

Fig 551. - General Arrangements of Kortlng's Low-presure Steam Apparatus.

vessels , R and r', is equal to the total cubic contents of the radiators, the steam connections, and the steam-space of the boiler.