“The Kensington Smoke-consuming Grate” (Brown and Green, Finsbury Pavement, London) is an underfed grate, and has received high commendation from good authorities; it has not the complication of Dr. Arnott’s, and is of good appearance, being fixed in a similar manner to any ordinary grate.
“Hollands’ Patent Underfed Grate” (Hollands & Co., Stoke Newington) is a still further improvement, and, except for a little complication in construction, may be considered the best in action and results. The advantages of underfed grates are, firstly, an abatement of the smoke nuisance, full utilisation of the fuel, and more powerful radiation from the top of fire, which is always incandescent. There is commonly no provision made for the supply of air for combustion, nor to replace that which is taken from the apartment by the draught in the chimney—the cracks and fissures around doors and windows sufficing for this purpose, is the too commonly general idea; but for perfection in warming upon hygienic principles, there must be a proper supply from external sources; but this will be more fully treated under Ventilation; it will, however, be noticed that some of the ventilating stoves make provision for this in themselves; this particularly applies to Captain Galton’s principle.
Close-Fire stoves.—The old form of close-fire warming and ventilating stove is that known as the “Cockle.” It consists of a closed circular fire-box with a dome top and a similar shaped outer casing; between the fire-box and the casing is a space of a few inches all round, known as the air-chamber, which by means of a pipe is connected with the outer air. The action is similar to a flue; the air within the air-chamber, being in contact with the heated surface of the fire-box is warmed, and rises and flows out at the top through an aperture provided at the top (as explained with the Wharncliffe grate), or it is made with a nozzle at top to attach a pipe and carry the warm air wherever required, so making it a hot-air furnace, in which case it would be fixed in a basement or cellar as at the best it is not ornamental, but this primitive form of stove has gone somewhat into disuse.
40. Thames Bank Iron Co.’s Stove.
Where a continual genial warmth is required at little cost in an apartment, the slow-combustion stove, such as that made by the Thames Bank Iron Company, London, (Fig. 40), may be employed. The external air is drawn in by a smoke-pipe channel and impelled through orifices in the stove. The smoke can be made to pass out at any level in the stove that may be found most convenient, but unless there is a high chimney shaft 25 to 30 ft., an underground flue connection is not recommended. The fuel, consisting of coke or cinders broken small, is supplied at the top, the ashes or cinders being removed through a sliding door at the base; a special soot-door is provided for clearing the flue before lighting the fire.
This appears an appropriate moment to mention that additional results can be obtained from close-fire stoves, by carrying the smoke flue down, and just below the floor level, in a properly made channel, and covered by a grating, as with hot-water pipes. It is known that a good proportion of the heat must be carried away by the flue, so that by this means nearly the whole of the heat evolved by combustion can be utilised; but it is necessary to bear in mind that the Building Act prescribes that no hot-air or smoke-pipe shall be nearer than 9 in. from any woodwork or inflammable material, and it is necessary that the main flue be high, as a good draught is needed to withdraw this nearly cold smoke or vapour, and in many instances where the under-floor horizontal flue is of good length, a pilot stove or rarifier is necessary at the foot of the main up-flue to keep up the draught, but in most cases the rarifier is only needed at first lighting. This arrangement is rarely applicable in dwelling-houses.
Improved forms of close-fire stoves are as multitudinous as improvements in open-fire grates; they are made either wholly closed, generally called “slow-combustion stoves,” and are arranged to burn many hours without feeding; or, as convertible open and closed; the latter have the advantage of the cheerful radiating fire when open.
“The Tortoise Slow-combustion Stove” (makers, Portway and Son, Halstead, Essex) is finding a ready sale and considerable favour, as maybe judged by the fact of its being obtainable at nearly any ironmonger’s. This stove, as with the majority of slow-combustion stoves, consists of an ornamental outer casing (cylindrical, square, or hexagonal), the height being about 2½ times the diameter; this casing is lined with fire-brick, and constitutes the fire-box; there is an ash-box and door below, in which is fitted a ventilator or damper to regulate the draught and speed of combustion. The fuel is supplied through a door provided at the top, and the smoke outlet is also placed near the top. In use, the fire-box is filled with coke and cinders, and the draught is regulated by the ventilator; it will then burn, and heat an apartment for many hours without attention. It is a very useful form of stove for greenhouses (in which case it would be fitted with a vaporising pan), halls, offices, &c., but hardly suited for living-rooms; the fire-brick lining tempers the heat, but if in use where children or dresses would come in contact, a guard must be provided. Slow-combustion stoves are made in a variety of forms, and the effect is very pleasing when externally fitted with tiled panels, &c.
For slow-combustion stoves that are required to burn for a longer than usual period without attention a chamber or hopper is fitted on top to take a further charge of fuel; it is taper-sided and open at the bottom, very much like an inverted pail, but about 2½ ft. high. It will be readily understood that as the coke is consumed, the upper supply gradually sinks down until the whole is consumed; this would utterly fail with a fuel that cakes, such as soft or bituminous coal.