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Air Stove

heated, chamber, cockle, flue, heat, upper, temperature, iron, lower and flues

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AIR STOVE. A stove, the heat of which is employed to heat a stream of air directed against its surface, which air is then admitted to the apartments requiring to be heated. The principle of the construction is, to inclose the stove containing the fuel in a casing somewhat larger than the stove, so as to leave a space of a few inches between them. At the lower part of the casing is an aperture filled with a register to regulate the admission of the air, and at the upper part is a similar opening to allow of its exit. When the air-stove is not fixed in the apartment which is to be heated, a pipe is fitted to the upper aper ture of the casing, to convey the air to the apartment. The construction may be varied to suit circumstances; the above cut is a representation of one which has been used with very good effect to heat the Infirmary at Derby. It is upon a plan which was first introduced in this country by Mr. Strutt, of Derbyshire who employed it for the purpose of warming his extensive cotton works more uniformly and with greater economy than formerly. Fig. 1 is a section of the air-stove and cockle ; and Fig. 2 a transverse section of the stove, exhibiting the disposition of the masonry surrounding the cockle. a, the cockle, is made of a cubical form, with a dome, or rather a groined arch top, about 3 or 4 feet high, and is made of plate or wrought iron about t of an inch thick, riveted together like the ordinary boilers of steam-engines. smoke passes off by a narrow passage at b, at the base of the cockle into the flue c, which leads to the chimney. The brick-work surrounding the cockle is built with alternate openings, as represented in the side view at f, at about 8 inches distant from the sides of the cockle. Through these apertures pipes are inserted which may be made either of sheet-iron or of common earthenware, so as to extend within an inch of the cockle, by which means the air to be heated may be thrown near, or in imme diate contact, with the surface of the cockle if desirable, which was found by Mr. Strutt to double the effect derivable from the same quantity of fuel. The horizontal partition of the air chamber at d cuts off the communication between the lower and the upper half of the chamber. The arched openings in the lower half g g exhibit the openings of the main air flues leading from the exterior atmosphere. The air passing from these lower flues g through the apertures beneath the horizontal partition d d, and coming in immediate contact with the body of the stove, must find its way into the upper air chamber h, through the numerous apertures or pipes in the upper division, by which circuit its velocity will be retarded sufficiently to obtain the necessary elevation of temperature from the heated cockle. In order that the air may not be injured for the pur poses of respiration, the size of these Belper stoves, as they are called, must be so regulated as not to heat the cockle or body of the stove at an average above 280° False., or according to Mr. Sylvester, or 250° according to Mr. Tredgold, when the air is intended to supply living rooms ; but for drying rooms more heat may be given, if the saving of time is an object ; but still it is far more economical to dry at a lower temperature. From the upper, or hot-air chamber A, a main flue i leads to each of the floors to be heated. The horizontal and

inclined parts of these main flues should be made of brick or stone, and if they have to pass under ground, should be secured in a case. The vertical parts may be of sheet iron, or even of well-seasoned wood. An opening over the door of each room allows the entrance of the heated air into it, and a flue from the bottom of each room proceeds to the roof of the building, from whence the whole of the air is discharged by a tumcap, the mouth of which is kept con stantly from the wind by a vane. Provided a stove of this construction is well built, and so managed as not to allow the heated air to attain too great a tem perature, it is not only much more economical than any other mode of warming extensive buildings, but it is equally salubrious with the more recent method of employing steam pipes for this purpose, if not more so. As the air passages of this kind of stove ought to be several feet under ground, it affords also a con venient mode of admitting a portion of cold air to the interior of the building in the summer season, as well as supplying heated air in the winter. The change in the temperature of the air by passmg in this way, Mr. Sylvester says, is greater than could be supposed. The cold air flue at the Derby Infirmary is about 4 feet square, and its length 70 yards. In the month of August, when the thermometer in the shade stood at 800, the air which entered the air flue underground at the same temperature, was found to be 60° at the extremity where it entered the stove-room ; the current at this time was sufficient to blow out a lighted candle. In another experiment, when the outer air was 540, this air was reduced to 510 by passing through the flue. This is a great advantage of the air stove above the use of the steam apparatus, since this last only supplies the deficiency of heat in winter, but has no tendency to check it when the tem perature of the atmosphere is beyond the mean temperature of the earth. But although close stoves, and air stoves in particular, are decidedly more effective and economical than open fire places, still the prejudice is so strong in England in favour of the latter, from their more cheerful appearance, and their freedom from any unpleasant and confined smell which is apt to arise from stoves when they become highly heated, that there seems but little chance of the latter superseding the former. It is therefore desirable, if possible, to derive from an open fire-place a portion of the advantages of an air stove, and accordingly, many combinations with that object have been devised. The following one is by Mr. Ricketts, of the Strand; besides the grate, it comprises an oven, boiler, and hot air chamber, all heated by one fire, without flues. No.1 represents the range, as fixed; No. 2,..the hot air chamber distinct; No. 3, a vertical elevation of the same chamber: the same letters in each figure refer to similar parts. a the hot-air chamber ; b cold-air drain, or aperture, at bottom of the chamber ; c thin iron plates or ribs 21 inches wide, to direct the passage of the air against the heated back of the chamber, producing a current of hot air which may be communicated by pipes to any part of the building ; f conducting oven, heated by an iron knob g; h an iron boiler to which the steamers may be applied.

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