Part 14

_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.

Bacon’s system of heating by water under pressure (J. L. Bacon & Co., 34 Upper Gloucester Place, London, N.W.) is very good, as the pressure is regulated by a valve, and the temperature and pressure never become excessive. This system is worked by small, strong wrought-iron pipes, and the apparatus is wholly filled with water. The great convenience of the small-pipe system recommends it for all purposes, as it can be carried into almost inaccessible places, and can be utilised for warming air, as it passes through inlet ventilators, and for small drying and airing closets, towel dryers, and for numberless small but exceedingly convenient purposes which large cast-iron pipes would be very unsuited for; and the advocates of this system contend that as much heat is radiated from their small pipes as from the ordinary large ones, as the former are heated to a much higher temperature than the latter: in Bacon’s system the highest limit is about 300° F.

The subject of a supply of hot water for baths and other purposes will be discussed in the chapter dealing with the Bath-room. See also p. 995.

_Steam Heat._--Steam heat may well be compared with stove and furnace heat. Stove heat corresponds to direct radiation by steam, and furnace heat to indirect. The supply of fresh air from the outside to and over the hot-air furnace, and through hot-air flue into the rooms through registers, is virtually the same as when it is conveyed by means of steam-heated flues in the walls. Exhaust flues, for getting rid of foul air, are equally essential. The stove, as representing direct radiation in the same manner as the steam coil, or plate, in the room, has the advantage over the latter of some exhaust of foul air, however little, even when the smoke-pipe is not jacketed, for the steam heat has none. In comparison with open-stove heat, steam heat is at still greater disadvantage; for open stoves supply all the qualities of complete radiation--the introduction of fresh air and the escape of foul--to a degree wholly unattainable by steam heat, whether direct or indirect, or by hot-air furnaces, which always require special provision for the escape of foul air.

The advantage of stove and furnace heat over steam may be summed up thus:--It is more economical, more uniform, more easy of management, more suitable for small areas to be warmed, and is free from the noises and dangers of steam. Irregularities of the fire in steam heating are a constant source of inconvenience, and sometimes of danger. The going down of the fire during the night-time, or its neglect for a few hours at any time, is followed by condensation of the steam. On the addition of fuel and increase of heat, steam again flows quickly into the pipes where a partial vacuum has formed, and here, on coming in contact with the condensed water, it drives the water violently, and creates such shocks as sometimes occasion explosions; or, at least, produces very disagreeable noises and general uneasiness, and frequently causes cracks and leaks. Hence direct steam heat, which for warming purposes alone is altogether superior to indirect, has been well-nigh abandoned. Indirect steam heat places the leaks out of sight, but they commonly lead to mischief, and require special and expensive provision for access and repair.

_Chemical Heaters._--Many salts in solution are capable of absorbing a considerable amount of heat and slowly giving it off as they resume a crystalline state. That most generally used is soda acetate, but an improvement consists in mixing 1 lb. of soda acetate with 10 lb. of soda hyposulphite, the latter assisting the melting of the mass and retarding crystallisation. The mode of applying this principle is to nearly fill a sheet copper or other metallic vessel, such as a foot-warmer, with the solution, and seal it up. When required for warming purposes, the vessel is placed in boiling or hot water till the contents are quite fluid, after which it may be used as a source of heat for 12-15 hours. Obviously the vessel may be placed in an ornamental structure resembling a stove, or used as a foot-warmer, or a muff-warmer, and in many other ways where fire is inadmissible.

_Hints on Fuel, &c._--Suggestions for materials which may be used to eke out a scanty supply of coal cannot fail to be useful. One plan consists in well bedding lumps of chalk under small coal. This gives a long-lasting fire, but is apt to emit an unpleasant odour. Another plan is to make clay fire-balls, using common clay, coal dust and cinders with sand, in about the following proportions:--1 cwt. coal dust, 2 cwt. sand, 1½ cwt. clay, well mixing the ingredients, shaping into fist-like lumps, and drying over night before the fire; to be put on when the surface of the fire is clear.

Some further hints for reviving fires will be found under the Sick-room.

=Lighting.=--The illumination of a dwelling is a most important consideration, as regards comfort and health.

_Daylight._--Natural lighting is provided for by windows. The window area of a room should be well proportioned. In dwelling-rooms, it may amount to half the area of the external wall containing the windows; in churches, &c., ⅓ will suffice. Too great a window area is objectionable, as it considerably lowers the interior temperature in winter, unless very thick glass and double windows are provided. When windows become steamed or covered with condensed moisture in frosty weather, this can be cured by applying a very thin coat of glycerine on both sides of the glass. When direct daylight cannot be got, great advantage may be derived from using polished metallic reflectors.

_Luminous Paints._--Several bodies possess the property of absorbing a certain amount of light and emitting it slowly. The most important of these is calcium sulphide. This property has been utilised by mixing the mineral with paint as a covering for surfaces where the light is required. The illumination, however, is very feeble.

_Candles._--Candles will long retain a place in domestic lighting from their safety and convenience for carrying about. At the same time they are an expensive source of light, and not very powerful. It may here be mentioned that there is a right and a wrong way of blowing out a candle. If the candle is held on a level with the blower’s mouth, or blown down upon, as usual, as it stands on a shelf or table, the wick will smoulder and smoke till the room is filled with its disagreeable smell, and the wick burned away so that it can be lit next time with difficulty. If the candlestick is held well above the blower’s head, and the flame blown out from below, the ignited wick will almost immediately be extinguished, and no trouble will be found in re-lighting the candle. Avoid cheap candles; they burn rapidly to waste and play havoc with clothes and furniture by “dropping.” The best form of candlestick yet introduced is the “silver torch,” made by Wm. Nunn & Co., 204 St. George Street, London, E. By this the candle is converted into a lamp, with or without a globe as desired; the candle is completely consumed, leaving no ends, and guttering and dropping are quite prevented. Nightlights should always be burned under a glass shade, such as Clarke’s.

_Oil Lamps._--All lamps intended for burning animal, vegetable, or mineral oils as illuminants should have the following objects in view:--To supply oil regularly to the wick; to apportion the supply of air to the description and quantity of oil to be burnt; to provide simple means for regulating the height of the wick, and consequently, the flame; and finally, to place the burning portion of the lamp in such a position as not to be obscured by the reservoir and other portions. The oldest lamps, as the antique Etruscan, and the cruisie of Scotland, were on the suction principle, and the wick depended for its supply upon its own capillary action. As the level of the oil was constantly varying, so the light varied also, and the first attempts of inventors were directed to maintaining an equal level of oil. The bird-fountain and hydrostatic reservoirs partly attained this end, and the Carcel and Moderator systems were perfect of their class, mechanical or pressure lamps. It is evident that suction lamps depend for their efficacy upon the gravity of the combustible. A spirit lamp, with a good wick, will burn very well, though the wick be several inches above the liquid. With liquids volatilising at low temperatures, there is always a danger of the formation of explosive mixtures.

In the Silber lamp the burner is a simple aggregation of concentric tubes. The use of these, especially of the innermost, bell-mouthed pipes, becomes very apparent in the lighted lamp. Remove the interior tube, and immediately the flame lengthens and darkens, wavers and smokes. The current of air which is, by this internal conduit, directed into the interior flame surface, is the essential principle of Silber’s invention. The wick is contained in a metal case, surrounded by an air-jacket, which passes down the entire length of the lamp, leaving a small aperture at the base, through which the oil flows from the outer reservoir to the wick chamber. Thus, by the interposition of an atmospheric medium, the bulk of the oil is maintained throughout at a low temperature; 2 concentric bell-mouthed tubes pass down the interior of the wick case, and communicate with the air at the base of the lamp, which is perforated for the purpose; 2 cones, perforated, the inner and smaller throughout, the largest only at the base, surround the wick, and heat the air in its passage through the holes to the flame. The effect of these appliances is, firstly, by the insulation of the outer reservoir, to avoid all danger of vaporisation of the oil, till actually in contact with the wick. As it is drawn nearer and nearer the seat of combustion, the hot metal wick-holder heats, and ultimately vaporises the luminant, so that at the opening of the wick tube concentrically with the air conduits--all of which are exceedingly hot--a perfect mixture of vapour and hot air is formed, and burned. An all-important feature is the shape and position of the chimney, which influences the flame to the extent of quadrupling its brilliancy if properly adjusted. (Field, Cantor Lecture.)

The many fires and fatal accidents arising from explosions of mineral oil lamps has drawn official attention to the subject of rendering them safe. Sir F. Abel has stated that all channels of communication between the burner and the reservoir of mineral oil lamps should be protected on the principle of the miners’ safety lamp; he added that a simple arrangement which effected the desired object “with perfect safety” was to attach to the bottom of the burner a cylinder of wire gauze of the requisite fineness, which prevented the transmission of fire from the lamp flame to the air-space of the reservoir. Acting upon this suggestion, Hinks and Son, 60 Holborn Viaduct, have introduced a wire-gauze cylinder for use with their duplex lamps, which renders them absolutely safe. Another advantage with their lamps is the ease with which they are lit and extinguished, as shown in Fig. 48: for lighting, a turn of the thumb-key _a_ gently raises the cone, globe, and chimney, giving free access to the wicks; to extinguish them, it is only necessary to press the lever _b_.

The Defries safety lamp (Defries Safety Lamp and Oil Co., 43 Holborn Viaduct) is attracting much notice, on account of economy, safety, and illuminating power. The construction of the lamp is such that neither ignition of the vapour, nor outflow of the oil in the event of the lamp being overturned, can occur. Moreover, the oil reservoir, being of metal, is not liable to fracture. It therefore follows that the risks attaching to the employment of mineral oils as illuminating agents in lamps of the ordinary description are non-existent in this lamp. The light emitted is remarkably white, the flame is perfectly steady, and the combustion is effected without the production of the slightest odour or smoke. Results of photometric tests by Prof. Boverton Redwood were more favourable than any he had hitherto obtained with mineral oil lamps of other forms. The illuminating power is, for the size of the burner, in each case very high, while the consumption of oil per candle light per hour is remarkably small. The products of combustion are odourless, even when the normal size of the flame is much reduced by lowering the wick. Any mineral oil, as well as the Defries safety oil, can be used in these lamps. This is quite odourless when spilled or heated, requires a temperature of 308° F. (or 96° F. above the boiling point of water) for its ignition, and does not vaporise below 270° F. Such oil is no more inflammable than colza oil, and is moreover free from the risk of spontaneous combustion. Its price is 1_s._ 6_d._ per gal. The absolute necessity for using, in any and every lamp, the most refined and safest grades of mineral oil cannot be too seriously insisted upon, Cheap low oils mean personal risk.

_Gas._--Though gas is long since established as one of the most successful and general illuminants, it is surprising what ignorance exists as to the simple rules which should govern its use.

This section is not intended for the guidance of the professional gasfitter, yet some of the points to be noticed are really within his province, and are mentioned because the householder should be in possession of such knowledge as will enable him to discover or prevent faulty work.

Coal gas, being much lighter than air, flows with greatest velocity in the upper floors of houses; hence the supply pipe may diminish in size as it rises, say from 1¼ in. at the basement to ¾ in. on the 3rd floor. At a point near the commencement of the supply pipe it should be provided with a “siphon,” which is simply a short length of pipe joined at right angles in a perpendicular position and closed at the lower end by a plug screwed in. As all gas-tubes should be fixed with a small rise, this siphon will collect the condensed liquids, which may be drawn off occasionally by unscrewing the plug end. When the lights flicker, it shows there is water in the pipes: the siphon prevents this. The number of gas-burners requisite for lighting a church or other large building may be computed thus. Take the area of the floor in ft. and divide by 40, will give the number of fish-tail burners to be distributed according to circumstances. Example: a church 120 ft. long by 60 ft. wide, contains 7200 ft. area; divided by 40, gives 180 burners required for the same. Burning gas without a ventilator or pipe to carry off the effluvia, is as barbarous as making a fire in a room without a chimney to carry off the smoke. If a pipe of 2 in. diameter were fixed between the joists, with a funnel elbow over the gaselier, and the other end carried into the chimney, it would be a general ventilator. Of course, an open ornamental rosette covers the mouth of the tube; or an Arnott valve ventilator over the mantelpiece would answer the same purpose. In turning off the gas-lights at night, it is usual, first, to turn off all the lights, except one, and then turn off the meter main cock, and allow the one light to burn itself out, and then turn it off. The evil of this system is this,--by allowing the one light to burn itself out, you exhaust the pipes and make a vacuum, and of course the atmospheric air will rush in. The proper way is to turn off all lights first, and finally the meter, thus leaving the pipes full of gas and ready for re-lighting. These few remarks have been derived from Eldridge’s ‘Gas-Fitter’s Guide,’ an eminently useful and practical handbook.