The objections to this form of stove arise chiefly from the formation of deleterious gases, which are not carried off completely. The slow combustion of the fuel produces a large quantity of carbonic oxide, which is liable to escape into the room, and is of an injurious character. Carburetted hydrogen gas is also formed in these stoves. Many modifications of form have been suggested for the remedy of these evils; but the slow combustion, which was one of the merits originally claimed for the stove, and which it certainly deserves, seems an unavoidable cause for the production of these gases.
All the varieties of open fire-place, as adopted in English houses, the hearth, the recess, and the chimney, are at one side or at one corner of the room; but in the adoption of close stoves this arrangement is not necessary; for the stove may be in any part of the middle of a room, provided the pipe constituting the flue be long enough. In some cases this pipe is carried upwards to the ceiling, and thence conveyed to some outlet into the open air; in other cases it is turned downwards and conveyed under the flooring to a proper place of exit; while in others the pipe is stretched or extended horizontally from the stove to the regular chimney of the room.
Warming Buildings by Heated Air.
Our builders have not yet entered so far into the mechanical contrivances of the age as to dispense with chimneys altogether; nor could such a thing be done until a total change is effected in the opinion of persons concerning the cheerfulness of an “open fire.” But there are nevertheless three modes, more or less adopted in the present day, whereby a house is warmed without the necessity for anything like a fire-place. These methods—in all of which the heating agent is brought from another room into the one to be warmed—are of three kinds; heating by hot air, by hot water, and by steam.
When we speak of warming an apartment by heated air, it is necessary to give precision to the meaning of the term. All rooms are, in fact, warmed by heated air, for the stove or grate must raise the temperature of the air in the room before we can appreciate the sensation of warmth. But what is generally meant by the term as here used is the warming of one apartment by air heated in another. The stoves used in Russia, though not coming exactly under this description, will serve in some degree to illustrate the principle.
The Russian stove is intended as a sort of magazine, in which a great quantity of heat maybe quickly accumulated, to be afterwards slowly communicated to the apartment. The stove is therefore made of a massive size. It is formed of brick-work, clay, glazed tiles, which together form a great mass of matter to be heated by the fuel; and there is in every part a considerable thickness of slow-conducting material between the fuel and the air of the room. The fire is kindled early in the morning, after which the stove door is shut, and the air aperture below left open for some time as a means of admitting draught to the fire; but in the course of a short time the fire-door is opened to check the draught, so as to prevent the too rapid combustion of the fuel. In this way the combustion is allowed to go on, and the substance of the stove becomes warmed, after which the air passages are shut, so as to prevent any abstraction of heat by the current that would otherwise be occasioned. The stove thus becomes a great mass of heated matter, which is gradually pouring warmth into the apartment during the whole of the day; and as the temperature of the surface never becomes very high, the impurities in the atmosphere are not decomposed, and it is consequently free from those offensive effluvia, unavoidable when metal stoves are used. The fuel is allowed to be nearly burnt out before the apertures of the stove are closed; and therein the stove differs greatly from those hitherto considered; the heated air within the stove being so completely shut in that it can find no outlet, except through the substance of the brickwork.
The modifications of the arrangements whereby warmed air is conveyed from one room to another, may next be noticed. In such cases the air either escapes from a heated receptacle outside the fire-case, or else it merely passes over a heated metallic surface. The following description relates to one variety of the first of these two methods. In the lower part of a house or building is a cast-metal double stove; the inner part forming the stove, and the outer one the case or envelope. The fuel is burned in the inner stove, and the smoke produced during the process of combustion is carried off by a chimney, which passes through both stoves or cases, and is conveyed to the outside of the building. The outer case includes not only the furnace or inner stove, but also a considerable space occupied by the air of the atmosphere, which is freely admitted through a number of holes placed around it; and when any current of warmed air is produced, it passes off from the space between the outer case and the inner stove, and is conveyed by tubes to any apartment in the building; so that the rooms are warmed by the air which has passed between the outer case and the inner stove.
In another form of arrangement, having the same end in view by means of heated air, the air, instead of passing through an enclosed space between the outer case and the inner stove, passes over a surface of metal which is heated either by a fire underneath, or, which is better, by steam or hot water contained in pipes. The temporary House of Commons, the Reform Club-house, and many other buildings, are warmed in this way.
The following simple and cheap form of stove has been erected in the cottages of Sir Stewart Monteath’s labourers. The accompanying figure represents a section of the stove, the principle of which will be understood from the following explanatory notes:—
