Chapter VI: Preface (6)

“The Manchester Warming and Ventilating Grate” (E. H. Shorland, St. Gabriel’s Works, Manchester) is somewhat similar in principle to Captain Galton’s grate, i.e. the warm fresh-air inlet is at the ceiling, and the vitiated air is carried off by the chimney, or in some instances ventilation at a lower part of the room is provided. Fig. 33 will acquaint the reader with the details: _a_, fireplace; _b_, outer wall; _c_, inner wall; _d_, smoke flue; _e_, _f_, cold-air inlets; _g_, _h_, warm-air passages; _i_, inlet for cold or warm air into room.

The shape of the back brick advocated by Dr. Teale (first invented by the celebrated Count Romford, to whom much is owing for the various means undertaken by him to promote the consideration of the question of improving our fire-grates and to abate the smoke nuisance) has since its discovery met with universal favour, and is coming into general use by all makers, as the expense of the stove is scarcely increased and its result in use is a most decided improvement. The actual shape or section of this brick varies with the different stove makers, but the result is the same; the brick is made to slope forward from the bottom up to about 15 or 16 in. high; at that height the top of the brick overhangs the bottom by about 5 to 6 in.; its section is appropriately defined by a maker, who likens it to a “dog’s hind leg.” Some makers shape the brick like a curved scallop-shell, inclining forward at the top; the effect is that as the heat ascends from the fire, it strikes or comes in contact with the projecting part, and rebounds or is deflected into the room; it is a similar action to that which takes place if an object, say a ball, is thrown upon a wall and comes in contact with a similar projection--it would bound off or be deflected.

It would be impossible to describe all the existing improvements upon the ordinary or old form of open-fire stove (commonly known as a “register grate”), but the following are some that are tolerably well known and have a good share of favour.

“The Abbotsford Slow-combustion Grate” (Mappin and Webb, Cheapside, London), which has now been used some years, was about the first recognised form of stove that had the bottom closed, so that the supply of air for combustion is carried through the front only. This is a great improvement (as explained by the economiser), by lessening the consumption of fuel without decreasing the efficiency or its heat-giving properties. The bottom of the fireplace is a solid fire-brick slab, and the chief property of this stove is truly named “slow combustion.” Many people have tried to apply this advantage to existing stoves by having a piece of iron cut to lie _upon_ the bottom grate; but iron is too rapid a conductor, and failure is experienced by having the lower part of the fire dull and dead. It cannot, however, be said that a solid bottom is the best, for it permits of accumulation of ash, and it is slow lighting.

“The Wharncliffe Patent Warming and Ventilating Grate” (Steel and Garland, 18 Charterhouse Street, London, E.C.) Fig. 34, is an excellent form of grate, and is fixed back against the wall, wholly projecting into the room, an air-chamber surrounding the fire-box; this air-chamber is, whenever convenient, connected with the outer air by means of a pipe, and within the chamber gills or ribs are provided, attached to the fire-box (the principle and advantages of these gills or ribs, which are to increase the heat-giving surface and to prevent over-heating of air, will be explained under Gill stoves).

When the fire is established, the metal of the fire-box becomes heated, which then heats the air contained in the air-chamber, rendering it lighter, whereupon it rises and flows out into the room through the perforations provided in the pattern of the ironwork; cold air immediately flows in to take its place, which is then heated, and passes out, so that as its name implies it is a ventilating as well as warming grate, and has the further advantage of the cheerful open radiating fire; but it must be remembered that with ventilating stoves there must be provision made for the removal of vitiated air, which in this case is taken up the chimney along with the products of combustion.

Another improved form of warming and ventilating grate is that invented by and named after Captain Douglas Galton (makers, Yates, Hayward & Co., Upper Thames Street, London). The principle advocated in this instance is contrary to that generally adopted, insomuch that the warmed fresh air is admitted into the room near the ceiling, and the abstraction of vitiated air is performed through the grate by the chimney draught. This is an open-fire grate fitted within a mantel in the usual way, and is provided with an air-chamber at the back, and which is connected with the outer air as before explained. From this air-chamber a perpendicular shaft or flue is carried, terminating by being turned into the room with an inlet grating or louvre. As before explained, the air within the air-chamber is warmed, and rises and passes into the room close to the ceiling; from there it is drawn down towards the fire, and eventually passes up the chimney, so that there is always a current of warm fresh air from the ceiling downwards. There are as many advocates for this down-current system as for the up current, as in the Wharncliffe and others. The Captain Galton has had about 14 years’ trial, and is still largely used. A rather peculiar and advantageous action takes place, by the fact that the apartment becomes fully charged with fresh air and the supply for combustion and draught is not drawn from the crevices beneath doors, &c., so that when a door is opened no inrush of cold air is experienced. This and the Manchester grate can most conveniently be used for warming another apartment also from the same fire.

“The Nautilus Grate” (Jas. B. Petter & Co., Yeovil), Figs. 35 and 36, is, as the name signifies, shell-shaped. The products of combustion rise from the fire, and after revolving within the centre or axis pass off by two concealed flues at the back of the grate to a flue prepared in the back of the fireplace; the ashes fall through a small grating into a closed ash pan. The warmth radiated direct from the cheerful open fire and indirectly from the outer case is considerable, and the results are very satisfactory, as no heat is lost by conduction. This grate is also cleanly, economical, and portable. The back, cheeks, and hearth should be tiled; the extra expense is fully compensated for by the handsome appearance.

The “Ingle Nook,” Wright’s Patent (GEORGE WRIGHT & SONS, 113 Queen Victoria Street, E.C.), Fig. 38, is a combination of all the most recent improvements, with two new features never before introduced into this class of grate, viz. the regulation of draught by means of an ordinary damper, and the complete independence of the actual working part of the stove, so that it may be removed at any time for repairs without disturbing the outer casing or brickwork.

_Special features and advantages_.

Radiation and complete utilisation of the heat generated from all parts of the grate, as not only the heat given off from front of fire, but also all heat radiated from sides and back of grate, which is usually absorbed in brickwork, is here passed into warm-air chambers and thence into the room. Economy of fuel, with increase of heating power. Prevention of down-draught, and partial consumption of smoke. Simplicity of construction and fixing, so that easy access is afforded to all parts of the grate, more especially those likely to want renewing. Pleasing appearance of the ordinary open fire, with heating power of a warm-air stove. This stove being complete in itself can be fixed by any ordinary workman without removing the mantel-piece or in any way interfering with the decorations of the room. The whole construction and principle of the grate are so simple that they can be readily understood by reference to the plan and section annexed. The interior portion of fire-box is of fire-brick, and can readily be removed from the front without disturbing any other portion of the grate. The back leans forward, deflecting the radiant heat into the room, and contracts the throat of the flue so as to quicken the draught directly the fire is lighted, which flue then expands and is again contracted at the top by means of the damper. Less than half the quantity of fuel is required to warm any given space, and more than double the quantity of heat is given off than from an ordinary grate with the usual supply of fuel. By introducing a fresh-air flue where practicable the perfection of ventilation may be obtained. The cost does not greatly exceed that of an ordinary grate, and is very much below that of any other grate of this description at present in the market. _See advertisement in front of title page._

“The Rumford-Teale Grate” (made by Verity Bros., 98 High Holborn, London), is made nearly wholly of fire-brick, upon strictly scientific principles, as the name indicates. There is very little iron in its construction, the front being a steel wire trellis instead of bars; this permits free radiation from the front and reduces loss by conduction. This front, apparently fragile, lasts for a considerable time (4 or 5 years), and is easily replaced by any one at an extremely small cost.

An improvement upon the Rumford-Teale grate is the “Eclat,” by the same makers, shown in elevation and section in Fig. 39. Its distinguishing features are a double flue (one for quick and the other for slow draught), and the projection of the fire in advance of the chimney breast. The figure shows: A, damper for regulating combustion; B, perforated fire-clay back; C, tiles to taste; D, economiser; E, ashpit; F, chimney breast; G, frieze; H, removable bottom grate with fine mesh; J, valve for regulating combustion.

There are several forms of combined open- and close-fire stoves, which stand independent of any brickwork, and are generally known as “American stoves.” These stoves are good heat givers, ornamental, and have several advantages, and can be obtained at almost any hardware stores; they do not work upon strictly hygienic principles, as they are apt to get overheated when closed, and render the air unpleasantly dry; but this can be remedied to some extent by using a vaporising pan, as will be explained later on.

There is another form of open-fire grate that should be mentioned, viz. those that have the fire replenished by placing the fresh fuel underneath, and are known as underfed smokeless grates. This idea, which deserves high commendation, has been rendered practical, but cannot be said to be perfected yet. It originated in Dr. Arnott’s stove, which was made with the usual set of front bars fixed about 12 in. high from the hearth, and the space under the bars closed in front. The bottom of the fire, which is movable, is lowered down to the hearth and the space filled with coal: the fire is laid, and ignited on the top of this store of fuel. As the fire burns down, the bottom grating is raised by means of a lever bringing fresh fuel within the fire-basket, and this bottom is raised as often as the fire burns down; it will be seen that the gaseous products given off by the fresh fuel must pass through the incandescent fire, and so be perfectly consumed, and the space below the front bars is sufficiently large to hold fuel for one day’s consumption.

“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.

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.

“Musgrave’s Patent Warming and Ventilating Stove,” Fig. 41 (Musgrave & Co., Limited, 97 New Bond Street, London), is made upon the slow-combustion principle, to burn from 8 to 24 hours, but is much more highly finished than the last named, and is constructed in so many patterns and sizes as to be suitable for almost every purpose, from small dwellings to the largest buildings. The stove consists of an outer casing, within which is contained the fire-box and an air-chamber. The latter is provided with gills to increase the heating surface (see Gill stoves). The smoke and heat when leaving the top of the fire-box is carried down a flue-way to the bottom of the stove, and then up to the top again into the smoke-pipe; this flue-way is within the air-chamber, and so utilises the major portion of the heat passed into the flue; the fuel to be used is coke, which is the most suitable fuel for all slow-combustion stoves.

For conservatories or where the air requires moistening these stoves are very neatly and effectually fitted with vaporising pans; and these stoves are also made to act as hot-air furnaces, and in combination with hot-water-pipe heating apparatus.

Roberts’ patent terra-cotta stoves operate also by slow combustion and are self-acting, but possess the additional advantage of purifying and radiating the heat by the terra-cotta, which is contained between 2 concentric cylinders of sheet iron united at the base and top, the outer cylinder being perforated to allow of direct radiation of heat from the terra-cotta. The stove consists of 4 separate parts, namely, the stove body, its top or cover, the fire-box, which can be lifted in and out, and the stand, with draw and damper. The fire is lighted at the top and burns downwards, the air sustaining it being drawn upwards through the bottom of the fire-box and thence through the fuel. The stove can be placed in any position on an iron or stone base and connected with the nearest chimney flue by an iron pipe provided with soot-door elbows, care being taken to form a complete connection by abandoning any other open fire-grate in the room and screening it off by an iron or zinc plate. They emit no effluvium, as the terra-cotta gradually and completely absorbs all the caloric in its permeation through the shell before it is communicated to the outer air, which is thus warmed and diffused in a healthy condition over the room. The top of the stove is movable, so that the fire-box can be removed to be cleaned and recharged without moving the stove body, and a sand groove is inserted at the top where the cover rests, which is filled with fine dry sand to prevent any escape of smoke.

Close-fire stoves, consisting of a strong iron fire-box, on to the outside of which is cast a series of vertical, parallel plates or ribs, are known as “Gill” stoves, as the plates or ribs referred to somewhat resemble the gills of a fish. These stoves are provided with a door for replenishing the fire, with ash-pan and ventilator below, and the iron base upon which the stove stands is made hollow, and has a series of holes or perforations opening between the gills, and provision is made for connecting the base with the outer air whenever convenient. It must now be explained that the object of the gills is to extend the heat-giving surface of the stove. It is known that iron is a very rapid conductor of heat, and consequently when the iron of the fire-box becomes heated, the heat is as quickly transferred to and felt at the extremities of the gills. It will be readily understood that only a certain amount of heat is given off by the fire, and the greater amount of metal it is transferred to, the lower must be its temperature; this is the chief and real advantage, as instead of a small volume of air being heated to a very high temperature, off a plane surface that would possibly get red hot, there is a larger volume of air at a lower temperature, and this has the further decided advantage that the air does not become unpleasantly dry, and the particles of dust, &c., in the air do not get scorched and burnt, and cause the unpleasantness commonly known as “burning the air.”

A further advantage possessed by these stoves is that they are not so much a source of danger, as the size of the gills is so proportioned to the size of the fire-box, that in ordinary use they cannot become excessively hot, and this is especially desirable where children or ladies’ dresses, &c., might come in contact.

These stoves can be obtained at any ironmonger’s or stove maker’s. A good form is that made by the London Warming and Ventilating Co., 14 Great Winchester Street, London, and is called the “Gurney” stove (Fig. 42). This is circular or cylindrical in form, with a dome top, and the gills, which are perpendicular, extend around the stove. A novel feature with this stove is that it is provided with a water-pan or trough carried round the base of the gills; when this pan is charged, the lower ends of the gills are immersed, and the heat that is conducted there causes the water to slowly evaporate. The advantage of a vaporising pan is this: before being warmed by an ordinary stove, fresh air holds a certain and proper amount of moisture, but as it becomes heated by such a stove the temperature is raised without proportionately increasing the moisture, and this is apt to make it unpleasantly dry, particularly to those suffering from asthma or any bronchial affection. The reverse is the case when the air becomes heated naturally (except when the wind is in the east); the proper proportion of moisture increases as the temperature rises; for instance, the atmosphere at 80° F. would contain about four times as much moisture as when at 32° F. The principle of the Gurney stove is such that the _natural_ degree of moisture is always maintained in the heated air. The greater proportion of modern close fire-stoves and furnaces have gills applied in some form or other.

It might be mentioned that 13 Gurney stoves have effectually coped with the problem “How to heat St. Paul’s.”

Another good form is “Constantine’s Convoluted Stove” (J. Constantine and Son, 23 Oxford Street, Manchester), Fig. 43. Instead of solid gills, there are a series of perpendicular convolutions which double the heating surface, and the makers’ claim to greater efficiency is no doubt correct. This stove, however, should be classed with hot-air furnaces, as it is not made in small sizes for direct heating; but for warming large buildings, churches, &c., for heating laundry drying-rooms, Turkish baths, &c., it is to be highly recommended.

The German principle, which might advantageously be adopted to a greater extent in England, is to build a fire-brick structure with the furnace at the base and the flue winding from side to side 3 or 4 times, and terminating at the top into an ordinary brick chimney; this structure projects into the apartment and is covered with porcelain ware, and the appearance often exhibits great taste and skill, as it will be understood that the structure is not rigidly square, but is often very beautiful from an architectural point of view. The good effect experienced is that after 3 or 4 hours’ firing, the mass of brickwork becomes thoroughly heated and the fire is permitted to go out; communication with the chimney is stopped by means of a damper, and every confidence can then be placed in the stove giving out abundance of warmth for the remainder of the day, as the brickwork takes hours to become moderately cool, and the whole of the heat it contains must be diffused into the apartment. It will be noticed that a minimum of heat is lost by this arrangement, and the result is very satisfactory from an economical standing; but it has not the cheerful appearance of our open fires, and efficient ventilation is required. This plan can, however, be satisfactorily adopted for halls or cold situations; in the former it has the further advantage in most instances of warming the stairways and landings in the upper part of the house by the ascension of the heated air. Fire-brick stoves are made by Doulton & Co., Lambeth, London, and are finished in their majolica and Doulton ware; it is needless to add, these wares give the stoves a very handsome appearance.

_Hot-air Furnace._--The close stove is really a hot-air furnace, but it is restricted to heating the air in the room. Other hot-air furnaces are designed to obtain a supply of fresh air and heat it before passing it into the room. The heated air from a fireplace is available to the apartment for only about 12 per cent. of the total amount of heat produced; all the rest passes up the chimney. The close stove, on the contrary, utilises 85-90 per cent. of the heat produced, and loses through the smoke-pipe only about as much as the open fireplace saves--10-15 per cent. And herein lies the striking difference between the relative healthiness of the atmosphere heated by a close stove and an open fireplace. The amount of air which hourly passes through a close stove, heated with a brisk fire, is, on an average, equal to only about 1/10 the capacity of the room warmed, and consequently such stove requires, if unaided, 10 hours to effect a change of the atmosphere in every such apartment. Thus stagnant and heated, the air becomes filled with the impurities of respiration and cutaneous transpiration.

Moisture, too, is an important consideration. The atmosphere, whether within doors or without, can only contain a certain proportion of moisture to each cub. ft., and no more, according to temperature. At 80° F. it is capable of containing 5 times as much as at 32° F. Hence, an atmosphere at 32° F., with its requisite supply of moisture, introduced into a confined space and heated up to 80° F., has its capacity for moisture so increased as to dry and wither everything with which it comes in contact; furniture cracks and warps, seams open in the moulding, wainscoting, and doors; plants die; ophthalmia, catarrh, and bronchitis are common family complaints, and consumption is not infrequent. But this condition of house air is not peculiar to stove-heat. It is equally true of any overheated and confined atmosphere. The chief difference is, that warming the air by means of a close stove is more quickly accomplished and more easily kept up than by any other means. Sometimes, by the scorching of dust afloat in the atmosphere, an unpleasant odour is evolved which is erroneously supposed to be a special indication of impurity, caused by the burning air. It is an indication of excessive heat of the stove. But the air cannot be said to burn in any true sense of the word, for it continues to possess its due proportion of elementary constituents. Such is the close stove and its dangers, under the most unfavourable circumstances.

The essentials for healthy stove-heat are brick-lined fire-chamber, ventilating or exhaust-flue for foul air, means for supplying moisture, and provision for fresh-air supply. A brick lining is requisite for the double purpose of preventing overheating, and for retaining heat in the stove. For the supply of moisture the means are simple and easy of control, but often inadequate. An efficient foul-air shaft may be fitted to the commonest of close stoves by simply enclosing the smoke-pipe in a jacket--that is, in a pipe of 2 or 3 in. greater diameter. This should be braced round the smoke-pipe, and left open at the end next the stove. At its entry into the chimney, or in its passage through the roof of a car, as the case may be, a perforated collar should separate it from the smoke-pipe. For stoves with a short horizontal smoke-pipe, passing through a fire-board, the latter should always be raised about 3 in. from the floor. A smoke-pipe thus jacketed, or fire-board so raised at the bottom, affords ample provision for the escape of foul air.

Hot-air furnaces are simply enclosed stoves placed outside the apartments to be warmed, and usually in cellars or basements of the buildings in which they are used. The manner of warming is virtually the same as by indirect steam heat--by the passage of air over the surface of the heated furnace or steam-heated pipes, as the case may be, through flues or pipes provided with registers. The most essential condition of satisfactory warming by a hot-air furnace is a good chimney-draught, which should always be stronger than that of the hot-air pipes through which the warmed air is conveyed into the rooms, and this can be measured by the force with which it passes through the registers. A chimney-draught thus regulated effectively removes all emanations; for, if the chimney-draught exceeds that of the hot-air pipes, all the gaseous emanations from the inside of the furnace, and if it have crevices, or is of cast iron and overheated, all around it on the outside will be drawn into the chimney. Closely connected with this requirement for the chimney-draught is the regulating apparatus for governing the combustion of fuel--the draught of the furnace. This should all be below the grate; there should be no dampers in the smoke-pipe or chimney, and all joints below and about the grate should be air-tight. The fire-pot should be lined with brick and entirely within the surface, but separate from it, so that the fresh air to be warmed cannot come in contact with the fuel-chamber.

An excellent plan for economising a good portion of the waste heat from a kitchen range is to have (previous to the range being fixed, or after, in some instances) a sheet-iron box or chamber made to fit at the back of the oven flues or wherever the most intense heat is felt. This box, which we may call an air-chamber, should be connected with the outer air, and a pipe for the warm air carried from the top of the box to the part where warmth is required; the heat from the range warms the air in the box and it ascends in exactly the same manner and upon the same principle as a hot-air furnace, but great care must be exercised to see that this box and all connections are made air-tight, or this plan will prove an unusually speedy means of indicating what is being cooked for dinner.

The Americans adopt what is called the “drum” principle of heating by means of a furnace; they not only encase the stove with an air-chamber, but the smoke-pipe is surrounded with a larger pipe encasing it all the way up; the space between the smoke-pipe and the outer pipe is thus an air-chamber and has free connection with the furnace air-chamber, but of course is closed at top; from the chamber surrounding the smoke-pipe, branch pipes are taken to the apartments, terminating in perforated cylindrical “drums,” from which the heated air is emitted.

It should go without saying that the air which passes from furnaces into living-rooms should always be taken from out of doors, and be conveyed in perfectly clean air-tight shafts to and around the base of the furnace. Preferably, the inlet of the shaft, or cold-air box, should be carried down and curved at a level (of its upper surface) with the bottom, and full width of the furnace. Thus applied, the air is equally distributed for warming and ascent through the hot-air pipes to the apartments to be warmed. On the outside the cold-air shaft should be turned up several feet from the surface of the ground, and its mouth protected from dust by an air-strainer. A simple but effectual way is to cover the mouth with wire cloth, and over this to lay a piece of loose cotton wadding. This may be kept in place with a weight made of a few crossings of heavy wire, and it should be changed every few months. And here, too, outside the house, should be placed the diaphragm for regulating the amount of cold-air supply, and not, as commonly, in the cellar.

As the best means of regulating the temperature and purity of the atmosphere from hot-air furnaces, it is necessary to provide sufficiently large channels for both the inlet of fresh air and its distribution through the hot-air pipes. The area of the smallest part of the inlet (or inlets, for it is sometimes better to have more than one) should be about ⅙ sq. ft. for every lb. of coal estimated to be burnt hourly in cold weather; and to prevent, in a measure, the inconvenience of one hot-air pipe drawing from another, the collective area of the hot-air pipes should not be more than ⅙ greater than the area of the cold-air inlet. These proportions will admit the hot air at a temperature of about 120° F. when at zero outside, and the velocity through the register will not exceed 5 ft. per second.

A large heating surface of the furnace is a well-recognised condition of both economy and efficiency. As a rule, there should be 10 sq. ft. of heating surface to every lb. of coal consumed per hour, when in active combustion; and the grate area should be about 1/50 of that of the heating surface. For the deficiency of heat, or the failure of some of the hot-air pipes of hot-air furnaces in certain winds and weathers in large houses or specially exposed rooms, the best addendum is an open fire-grate. With this provision in northerly rooms, to be used occasionally, hot-air furnaces may be made to produce all the advantages of steam heat in even the largest dwelling-houses.

Boyle’s system of warming fresh air is suitable where hot air, water, or steam pipes are not available. The arrangement (Fig. 44) consists of a copper or iron pipe _a_ about 1½ in. diam. placed in an inlet tube _b_, preferably of the form of a bracket. This pipe is not vertical, as in the so-called Tobin’s shafts, but of zigzag shape, crossing and recrossing the tube from top to bottom, and so causing the incoming air to repeatedly impinge in its passage through the tube. At the bottom of the tube an air-tight chamber, so far as the interior of the tube is concerned, is fixed, in which a Bunsen gas-burner _c_ is placed, the flame of which plays up into one of the lower ends of the pipe, the upper portion being about 5 ft. 9 in. from the floor. The other lower end of the pipe either dips into a condensation box _d_ in the bottom of the tube or is continued into an existing flue or extraction shaft. If the pipe terminates in a box, the vapour is condensed there and carried off through the outside wall by means of a small pipe. At the bottom of the box is placed some loose charcoal, which needs renewing at intervals. This charcoal absorbs any products of combustion which have a tendency to rise. The heat thus passes through the entire length of the pipe, and warms the air as it travels through the tube to the room or hall as required.

Heating by gas is now growing in favour, and under favourable circumstances is to be recommended. There are two general methods adopted; firstly, by gas fires, which are asbestos or metal made incandescent by gas heat; these are made either portable, or by fitting a specially made burner to an existing fireplace, and filling the grate with Lumb asbestos (which is made for the purpose, and when heated has the appearance of glowing coals); and secondly, by gas stoves acting upon a similar principle to a hot-air coal stove. The former are now made in great variety; they chiefly take the form of an ornamental iron frame, in the centre of which is fitted a fire-brick thickly imbedded in front with asbestos fibre; the burner beneath comes immediately under the front of the fire-brick, and when the gas is ignited, the asbestos at once becomes incandescent, making it of cheerful and fire-like appearance, and the fire-brick in a few minutes becomes highly heated, radiating its warmth into the room. This description of stove and also the burner for existing fireplaces can be obtained at any ironmongers or gas-fitters.

In nearly all gas fires and stoves the gas is burnt with an admixture of air (atmospheric gas, 1 of gas and 2 of air), by means of an atmospheric burner; this is not only a source of economy, but atmospheric gas has the very great advantage of being smokeless; but for this, a gas fire would be an impossibility; it must, however, be borne in mind that although smokeless this gas gives off products of combustion (carbonic acid, watery vapour, &c.), which must be carried away by a flue or other means. The portable stoves are always provided with a nozzle for attaching a smoke-pipe. There is still a doubt as to which is most economical, coal or gas: we cannot do better than quote the words of a well-known gas-stove maker, Chas. Wilson, of Leeds. He says, speaking of heating by gas: “It is not cheaper than coal, taking fuel for fuel and continually used, unless, as in the case of offices where labour has to be employed to light fires, clean grates, &c.; but it is cheaper than coal if occasionally used, as in the case of bedrooms, or sitting-rooms used by visitors, or rooms used by children for music, &c.; for bedrooms it is especially adapted for use for an hour or two at night or in the morning or for giving an unvarying heat all night. It is preferable in the matter of cleanliness, and a true solution of the smoke-abatement problem” (probably a coal-stove manufacturer would speak as much in favour of fire-grates).

It should be seen when purchasing gas fires that they have silent burners, as some make an objectionable hissing noise when in use.

“The Calorigen” Gas Hot-air Stove, Fig. 45 (Farwig & Co., 36 Queen Street, Cheapside, London), consists of an outer sheet-iron casing with a burner at the base inside, and proper accommodation for exit of products of combustion. A coil of good-sized sheet-iron pipe is affixed within the stove; the lower end of the coil is connected with the outer air and the upper end opens into the apartment, thus producing a free inflow of fresh air at any temperature desired, from 60° to 200° F. or higher at will. The chief advantage of a gas stove is the immediate lighting and extinguishing, and needing no attention.

Another modern and very useful application of gas as a heating medium is the “Geyser” or rapid water heater for the supply of hot or boiling water to baths, lavatories, &c., or for business purposes where it is not convenient or desirable to fit up a circulating boiler (see hot-water apparatus). These heaters can be obtained from any ironmonger’s or gasfitter’s. The principle is somewhat different in the various makes, but it all results in the same thing, which is to bring a small volume of water in contact with a large heating surface. The apparatus is generally cylindrical in form. A cock is at one side for attaching the cold supply, and the heated water flows out from a spout at the other side; there is also a cock for attaching the gas supply; they are made in various sizes to supply and fill a bath three parts full of water at 100° F. in 5, 10 or 15 minutes, or to boil water at the rate of ½, 1 or 2 gal. per minute. These are extremely useful appliances where gas is available, being ready for use at a moment’s notice, and the water can be had at any temperature at will; with a modern and properly constructed “Geyser” the water is quite suitable for drinking purposes.

The Marsh-Greenall Gas Heating Stove, Fig. 46 (makers, Greenall and Company, 120 Portland Street, Manchester), is both regenerative and radiating, the heat developed and utilised per foot of gas by this system being far greater than by the ordinary atmospheric stoves. Ordinary luminous flames are used, these being fed by superheated air. There is no smell and no danger “of lighting back.” The great heat obtained by this system is radiated from a polished reflector. The consumption of gas is only 12 ft. per hour. See Gas Heating also, p. 994.

_Oil Stoves._--Warming stoves which burn oil fuel are to be commended for many purposes, but are not generally considered suitable for living rooms--bedrooms, for instance--unless the air is continually changed by open doors, &c., as there is a noticeable odour from the burning oil. Rippengille’s are considered the best, and are obtainable at almost any oil, lamp, or ironmonger’s store, or at the chief retail agents, the Holborn Lamp Co., 118 Holborn, London. Fig. 47 is their “Eureka” cheerful reflector stove, suitable for office or shop use. These stoves are adapted for warming conservatories where a high temperature is not required, as a very small stove will suffice to keep the frost out; they are also suitable for servants’ bedrooms and attics where no fireplaces exist. They are made with metal (unbreakable) oil containers, which slide out for lighting, trimming, &c., and they burn the ordinary petroleum oil; it naturally follows that the better and more refined oils give the best results with these stoves, with less liability of smell.

_Flues._--It will not be out of place to give a short treatise upon flues, as the flues in a residence govern the efficiency of the stoves and the comfort of the whole household.

There is a common error in blaming the flue for all faults. It can be asserted that half the smoky chimneys are in no way the fault of the flue at all, and when a smoky chimney does exist, nearly every one flies to the chimney top with some device to govern the wind, and this in very many cases is a total failure.

Flues are now generally constructed of two sizes, 9 in. and 14 in. A 7 in. flue would be sufficient for most warming stoves, but it has to be borne in mind that the accumulation of soot quickly diminishes the size internally, so that they are now never built less than 9 in. internal diameter. In building a residence, the following plan is often adopted when cheapness is not the primary object, that is, to build the usual square brick chimney, and within this to carry up a 9 in. flue of glazed earthenware pipe (drain pipe), and the space outside this pipe filled with concrete: this pipe flue is so easily cleaned and is much less quickly fouled, and improves the draught.

The very general cause of smoky chimneys is that the chimney top is below the level of some adjacent building, tree, or other object that obstructs the free passage of the wind. In this instance the trouble is only experienced when the wind is in certain quarters, and sometimes this can be cured by a wind-guard or cowl (no particular make can be recommended, as their efficiency differs under different circumstances); but the only reliable remedy is to raise the chimney either by pipe or brickwork to the required height. The manner in which the annoyance is brought about is, that when the wind passes over the chimney top its progress is arrested by the higher object, and it may be said to rebound (the action is rarely quite alike in any two instances), causing either a portion of the gust to pass a short way down the chimney or to momentarily stop the up draught; this will be noticed by the gusts of smoke that come from the stove into the room.

When the smoke slowly oozes into the room, it is caused by sluggish draught, or often by the construction of the grate. If the grate has considerable distance between the fire-bars and the opening into the chimney above, it permits the heavy cold air to accumulate and obstruct the heated up-flow from the fire; this generally is only noticeable when the fire is first lighted or heavily fed. It is exactly the same result as is experienced with the old-fashioned open kitchen ranges, which nearly always require a sheet of metal or “blower” across the opening to prevent their smoking. The above-mentioned grates require a strong draught to work them perfectly; or if a strong draught does not exist, a small piece of sheet-metal should be provided to fit over the open space above the front bars when necessary to establish the fire, as explained with the “Eagle” grate.

Sluggish draughts are from a variety of causes, among which might be named, insufficient height of chimney; chimneys which by any cause may become damp or cold, or lose their heat rapidly; leakages, holes or fissures, and a variety of causes too numerous to mention here. The interior surface of a chimney should be as smooth as possible, and should be swept at regular and moderately frequent intervals, otherwise the draught will be reduced.

Every fireplace should have a distinct and separate flue; sometimes two fireplaces can be successfully worked into one chimney, but provision must be made for tightly closing off either one when not in use.

_Hot Water._--Heating by means of the circulation of hot water has been in vogue many years, but has not found favour for warming living-rooms and apartments, owing chiefly to the want of the air of comfort, and the warmth is not quite so agreeable as that radiated from an open fire; but this mode of heating is especially well adapted for conservatories, cold halls, public buildings, &c., as the heat-giving surface can be extended wherever desired, and so heat the place equally throughout; and upon the low-pressure system there is no danger, as the water cannot heat higher than boiling-point, 212° F., an advantage that the hot-air system does not possess. The principle and cause of hot-water circulation will be found fully described under hot-water apparatus; but in this arrangement there are no draw-off taps, the services being for circulating only. For small purposes the apparatus can be attached to the ordinary bath boiler of the kitchen range; but there is a serious disadvantage in this when the heat is for conservatories or where warmth is particularly required at night, as that is the time when the kitchen fire is not in use. For larger purposes, independent boilers are used, varying in size according to the requirements. Portable boilers with fire-box, &c., complete, can be obtained almost anywhere, and most slow-combustion stoves (the “Tortoise,” for instance) can be fitted with boilers for this purpose. It will be understood that these boilers do not require cleaning out like kitchen-range boilers, as there is no appreciable deposit, the same water being heated day after day and only losing say a quart per month by evaporation.

The arrangement for a hall with an independent boiler is to have several horizontal pipes suitably fixed one above the other and known as a “coil,” from which the heat is radiated, and this coil is connected by a “flow” and “return” pipe with the boiler: a small cistern of about 2 gallons capacity is connected with, and fixed a little above the level of the highest part of the coil in some convenient place. The apparatus is charged through this cistern, and a small quantity of water is added thereto periodically to make good loss by evaporation and to keep the coil full; these coils are usually covered with an iron grated casing, with a metal, slate, or marble top, which is both a useful and ornamental adjunct to the hall.

For conservatories the coil is not used, the radiating pipes being run along the wall near the ground; a portion of the pipe has a shallow open trough cast upon it, and this is filled with water. As the apparatus becomes heated, evaporation takes place, and this saturates the air, moisture being essential for this purpose.

For public buildings, &c., coils are sometimes used; but more often the pipes are run in grated-topped channels just beneath the floor, the grating being level with the floor-boards; they are taken around or across the building, as is most desirable to obtain an equable heat.

The radiating pipes, whether single or forming coils, are generally 4 in. diameter, of cast iron (cast iron being a better conductor or dissipator than wrought), and at the highest point m the apparatus a hole is drilled and a small cock is inserted; this cock is opened when charging, to allow of the free escape of the air in the pipes, and it is sometimes of service to discharge any steam that is generated. The pipes are made with a socket at one end, into which the plain end of the next pipe is inserted and packed with yarn, &c.; but a modern and rapid method of joining the pipes is that patented and manufactured by Jones and Attwood, of Stourbridge; this joint consists of two flanges with indiarubber packing between, which makes a perfectly secure joint by tightening the flanges together; in this method the ends of the pipes are of equal size.

As explained, the principle of circulation is exactly the same in this as in a domestic hot-water supply apparatus. The most popular form is that known as the Desideratum. The makers have also introduced a singularly useful tool for cutting all pipes from 2 to 13 in. diameter.

_High-pressure Heating_, or which might be correctly termed steam heating, consists of piping wholly, the pipe is smaller and of wrought iron unusually strong, and a coil of it placed within the fire-box fulfils the duty of a boiler (no boiler or large container can be used on account of high pressure); from the furnace coil the pipe is carried wherever required, a small quantity of water is put within the apparatus and the air is driven out, after which the apparatus is sealed or closed air and steam tight. When the heat is applied, the water quickly forms steam, which at once finds its way throughout the apparatus and heats it to a much higher temperature than boiling water; and there is comparatively no danger whatever pressure is exerted, as at the worst the pipe only splits, and no disastrous explosion can occur; but this mode of heating cannot be recommended, as it rarely works for any length of time without requiring attention or repairs.