[Ill.u.s.tration: FIG. 9.
Section of Hot Room, showing Foul-air Conduit.]
In the latter plan, however, a great expense is created by the large number of furnace-fires to be kept constantly burning. An exposed stove in a hot room, has, moreover, the objection to its use that it re-heats the air in the bath, which should never on any account be done.
If the iron stove-pipe system is adopted, a furnace similar to the one shown at Fig. 10 must be provided, and after an additional few feet of brick flue the iron pipe would commence and turn back upon itself much as the flue in the fire-brick furnace. Proper supports must be provided, and the pipes must be stout and jointed together with expansion joints, otherwise considerable difficulty will be found in keeping a long length of flue pipe perfectly free from leakage. Furnaces on this principle may be designed so that they throw a certain amount of radiant heat direct into the hot-rooms, and they possess this advantage over a mere stove, that they warm the air more gradually. The furnace should be built adjoining the laconic.u.m, the part.i.tion wall being of 4-1/2-inch glazed brickwork, having a large number of small openings made therein by leaving void s.p.a.ces as described further on for the fireclay heating apparatus. Behind this wall the iron flue-pipe should be placed, turning back upon itself, as described above, for perhaps half-a-dozen times, and ending in the vertical brick flue. The furnace itself should be of fire-clay, and so designed that its utmost heating power may be economically employed in warming the incoming air, which should pa.s.s over the furnace and iron flues, through the holes in part.i.tion wall, and thus into the hot rooms. The flue, if of wrought iron, should be rectangular in section, but if of cast-iron it should be round.
The most economical way of obtaining a high temperature in a small, inexpensive, and unpretentious private bath is by means of a common laundry stove, with a longer or shorter length of iron flue in the apartment. This is the cheapest and quickest method of raising the temperature of a room for sudorific purposes.
[Ill.u.s.tration: FIG. 10.
A Fireclay Heating Apparatus.]
To turn to methods of heating from a radiating surface of firebrick, at Fig. 10 I have given the plan, elevation, and sections of a fireclay heating apparatus. It is constructed wholly of fireclay--fireclay bricks, quarries, and cement. In the main it consists of a long flue of firebricks and slabs, which coils backwards and forwards over itself till the desired amount of radiating surface is gained. Between the coils are s.p.a.ces for super-heating the air already warmed by pa.s.sing over the actual furnace and into the warm air chamber, the air pa.s.sing through by means of perforated bricks. The ill.u.s.tration shows a simple furnace; but it would be an easy matter to improve upon this by providing iron air-tight doors lined with fireclay, for cleansing flues and air-chambers. The example given is only suited to heat a small public bath. For a large set of hot rooms, a compound apparatus could be constructed by placing an additional furnace in a sub-bas.e.m.e.nt, the one on the level of the sudatory supplying radiant heat, and the lower one hot air. Two such apparatus might be placed one behind the other, end to end, or might form the _sides_ of the laconic.u.m; the last plan, however, being the least to be recommended, as in such positions they would not directly radiate their heat into the adjoining hot rooms.
The advantage of such a furnace as that shown is that it supplies radiant heat of a most exhilarating kind, besides a proportion of heated air, and from a fireclay surface, the employment of which renders it absolutely impossible to overheat the air, or to contaminate it by deleterious particles resulting from the decomposition of metal.
Moreover, the stoking of this cla.s.s of furnace requires less arduous attention than an iron stove. Its disadvantage is that, should the temperature of the bath be allowed to fall markedly, it requires some time for the extra heat to be made up again. Inasmuch, however, as fires at public baths must be kept banked up overnight, this is not a matter of importance. It is this very slowness of increase in temperature that const.i.tutes the safeguard against that overheated air, the presence of which we can, with practice, detect by the smell in so many baths. The difficulties involved in the construction of a furnace of this nature relate to the prevention of cracking and consequent escape of sulphurous fumes and carbon into the air. The very simplicity of the construction of the flues and air-chambers const.i.tutes the chief danger, as the chances are that, unless the architect stands by and sees every joint made, the work will be done badly. Absolutely faultless workmanship must be employed throughout, and the fireclay materials must be literally of the very best and soundest description. Every single joint must be perfectly made with fireclay cement or paste. The fireclay bricks, &c., must be selected with regard to the amount of indestructible silica in the clay, consistent with hardness and toughness. h.o.m.ogeneity of material must be obtained, having regard to expansion and contraction.
The same material used for the bricks, &c., worked into a paste, must be employed for the joints.
The design for a furnace on the principle shown at Fig. 10 must be prepared with constant regard to expansion and contraction in heating and cooling. Should this warning be disregarded, fractures will result.
It will be seen, upon reference to the plans, that the block of flues and air s.p.a.ces is left quite free, to allow of any expansion, the connection with the smoke-shaft being by means of an iron flue-pipe, which, being provided in considerable length before pa.s.sing through the party-wall of laconic.u.m and stokery, by its flexible nature permits any slight movement in a vertical direction. If an "expansion" joint were provided, there would be a sufficient length of iron pipe if it pa.s.sed direct from the junction with the heating apparatus into the stokery. So much of the iron flue as is in the laconic.u.m must be coated with asbestos or some composition, or the heating will not be wholly by firebrick. The junction of iron flue and heating apparatus is shown by a cast-iron cap sliding over a projecting rim of fireclay, moulded into the last quarry cover, similar to the way in which cast-iron mouthpieces are fitted to retorts.
This heating apparatus is shown visible in the laconic.u.m, but if thought desirable it could be screened by a wall of glazed bricks--9 in. and miss 4-1/2 in. The 4-1/2 by 3 in. holes can be arranged in diamond patterns. This screen wall, however, cuts off a large quant.i.ty of radiant heat.
The first flue past the actual furnace--shown with ordinary dead-plate, raking fire-bars, ashpit, fire-door, and ashpit door for regulating draught--has walls 4-1/2 in. thick; above, smaller bricks, 3 in. wide; but in a larger apparatus, 9 in. and 4-1/2 in. respectively would be required. The quarries between flues and air s.p.a.ces are 24 in. by 24 in.
by 3 in., with rebated joints. Larger covers would be more liable to crack at any provocation.
In addition to heating by means of furnaces, steam-heating may be employed, if found, as in many cases it would be, convenient and economical. The chief disadvantage of this method of heating Turkish baths, is the constant danger, however slight, of bursting a pipe in the heating coil, which, by immediately filling the highly-heated atmosphere with vapour, might prove most disastrous to the occupants of the hot rooms, who would be seriously scalded. Nevertheless, the principle has been largely employed in the heating of the most recent Turkish baths in Germany.
If adopted it may be either on the hot-air or radiating plan, as in heating by means of furnaces. In the first method the fresh air is introduced into a chamber containing a coil of steam-pipes, and pa.s.ses thence into the laconic.u.m by a shaft or conduit, as in the case of air heated by a stove. In the second method, steam radiators--compact batteries of pipes--must be placed in recesses in the hot rooms, fresh air being introduced over them. The steam-pipes employed should be of the "small bore" type, about 5/8 inch internal diameter, and of wrought iron or copper. In order to ensure as far as possible against the danger of explosion, the system of pipes should be tested, when fixed, by severe hydraulic pressure.
It is certainly a great advantage, in point of ease and economy, to be able to warm a building, drive machinery, and heat Turkish and Russian baths from one boiler, which can readily be done, very ordinary pressures of steam giving sufficient heat to keep the radiators of the requisite temperature. But the nature of the heating accomplished by means of steam-pipes is very inferior to that from large radiating surfaces of firebrick.
The average temperatures of a public bath should range from about 110 in the shampooing rooms to 250-260 in the hottest part of the laconic.u.m, taking the readings of the thermometer at a level of 6 ft. 6 in. above floor-line. Between the entrance of the heated air and its point of furthest travel in the shampooing rooms, the bather should be able to select any temperature that may be most agreeable to him, and as many find by experience that a certain degree of heat is best suited to themselves, it shows attention to the _habitues_ of the bath, if the hot rooms are carefully maintained at the same uniform temperatures throughout the year. This may be 110-120 in the shampooing rooms, 140 in the tepidarium, 180 in the calidarium, and 250 in the laconic.u.m.
These must be the maxima of the average temperatures of each room at 6 ft. 6 in. above the floor. In a pure atmosphere the highest temperatures are comfortable, but in a foul one they become insupportable.
In a good bath, where there is a rapid and continuous flow of air, there will be comparatively little difference between the temperature at say 4 ft., 6 ft., and 8 ft. above the floor. In badly-ventilated rooms, where the air stagnates, there will be a considerable difference. And here we may note a serious objection to the heating of a bath by convection; for while the head may be in a high degree of heat the feet are in comparatively cool air, whereas, if possible, it should be just the reverse. In convected heat, this of course applies in its entirety, as where so-called radiant heat is employed the evil is not quite so marked. And here, too, we may note the admirable nature of the Roman system of heating, where the floors radiated the majority of the heat, and the walls a slightly less amount. The fresh air under the ancient system must have entered through the cooler rooms, and being drawn towards the _calidarium_ found its exit through the ceilings, at times by way of the regulating device mentioned by Vitruvius. Thus the ancient bather would not suffer the inconvenience that accrues to the bather in the modern hot-air bath, whose head, when he is standing upright, is in a considerably higher temperature than any other portion of his body.
The temperature of a bath should not be regulated by the firing of the furnace. This should be regularly stoked, and kept at one uniform heat-giving condition. Bad firing and forced firing may crack the stove should it be of iron, and the air may be overheated. The temperature should be regulated by means of the hit-and-miss ventilators at the floor level. Fanlights between the various hot rooms, with screw-rod adjustment, serve as a means for regulating their relative temperatures.
The heating power of furnaces must be studied. Having calculated the cubical contents of the rooms to be heated, and given the heating power of the stove or apparatus to be employed per cwt. of metal or superficial foot of radiating surface, we arrive at the necessary size.
Messrs. Constantine give the following tables to show the heating power of the "Convoluted" stove. The figures give the requisite size of stove to raise the air to about the relative temperatures I have mentioned before, and with ordinary firing.
Weight of Sq. ft. of Area capable metal. heating surface. of heating.
--- --- --- cwt. sq. ft. cub. ft.
14 35 500 20 55 1,200 22 69 2,000 34 119 3,500 36 139 5,000 45 180 8,000 50 231 12,000 56 296 16,000
When different kinds of heating apparatus are employed, their heating power must be carefully ascertained and calculations entered into, or it may be found necessary to resort to the costly and humiliating process of dragging out the stove or pulling down the furnace and refitting a larger one. This point is worth attention. Such mistakes are not unfrequently made.
As regards the amount of air that should flow through the hot rooms, an allowance of 40 cubic feet per head per minute should be the minimum, if purity of atmosphere is to be maintained. In a bath, the importance of perfect ventilation cannot possibly be over estimated, as not only has the respired air from the lungs to be removed, but also the deleterious exhalations from the skin which are produced by perspiration.
The allowance of 40 cubic feet per head per minute should not, if properly distributed, cause an unpleasant draught in any part of the hot rooms; for it must be remembered that even in a highly-heated atmosphere a waft of air of the same temperature is felt to be cold. The main thing to be studied in this provision of a large volume of air is that the cold inlet be ample, and the pa.s.sage from this intake to the point where the air is debouched into the laconic.u.m equally roomy and un.o.bstructed. The rapidity of flow will depend upon the means provided for the extraction of the foul air. With large horizontal flues, and a capacious and tall shaft, the so-called natural system of ventilation will be as effective as could be desired. Greater extraction power is gained if in the brick stack a smoke-pipe can be placed running up the whole height. In many cases mechanical ventilation could be employed with the greatest benefit. A powerful air-propeller fixed at the end of a system of horizontal flues under the floors of the hot rooms, and running so as to exhaust, would do away with all the objectionable odours and nastiness of many baths.
The purity or foulness of the air in the hot rooms forms all the difference between a good bath and a bad one, which latter is infinitely worse than no bath at all. There exist, at the present time, scores of baths where the odours of the sudatory chambers are nauseating. Such foulness arises from stagnation of the air. There is no continuous flow, and the respirations and exhalations of the bathers are not removed. A system of ventilation may be pointed out, but it is on the wrong principle, and does not act. There is no change of air. The atmosphere of such places becomes pestilential.
Owing to the expansion by heat, a relatively greater volume of air enters the laconic.u.m than the cold intake. This fact, however, does not practically affect the arrangements for ventilation, &c. Theoretically, however, it would seem to demand that the shaft conducting from furnace to hot rooms should be of greater sectional area than that to the furnace from the intake--about one-third larger--and that the total area of outlets for the escape of vitiated air should be about midway between the two.
The whole principle of the ventilation of the hot rooms of a Turkish bath resolves itself, primarily, into the fact that we have to continually remove _the bottom layer of air_. The provision of the foul-air conduits below the floor level is equivalent to providing a suspended floor with a hollow s.p.a.ce under. This is just the reverse of the principle of ventilating rooms of ordinary temperature, where we require to constantly remove the top layer, and often actually do so when we provide false ceilings to pa.s.sages, &c.
The ventilators placed at the floor level of the hot rooms should be actually so, and not 3 in. or 6 in. above. Long, wide gratings 6 in.
deep are preferable to those of deeper and narrower design. In theory, indeed, the whole circ.u.mference of the hot rooms should be lined round with gratings, thus making the sudatorium like a lidless box inverted, into which hot air is thrown and escapes all round the bottom edges.
There is one point about the circulation of air in a set of hot rooms that requires considerable attention, and that is the _back-flow_ along the floor. In any bath where hot air is supplied, if the bather will hold his linen "check" across the top of the doorway between the rooms he will find that the air is flowing from the laconic.u.m to the shampooing room. If, however, the sheet be held across the lower portion of the doorway, he will find that there is a current of air setting in an opposite direction--from the shampooing room to the laconic.u.m. This is shown at Fig. 11.
[Ill.u.s.tration: FIG. 11.
Longitudinal Section of Sudatory Chambers.]
It will be seen from the diagram that the bather is really in this back-flow when he is standing between and in a line with the doors of the hot rooms. All the air appears to be travelling along the top of the bath, and the bather reclining on the marble-topped benches would seem to be bathed in air that has pa.s.sed along the top of the bath, round the shampooing rooms, and back along the floor. In reality, however, it is only from door to door that the currents exist exactly as shown at the diagram, Fig. 11, there being a secondary circulating process in each room.
This circulation of air will exist in any bath heated on the modern system--that is to say, where freshly-heated air is pa.s.sed in in sufficient quant.i.ty. It is a natural result, and tends to distribute the heat more equally. The back-flow is only objectionable when a door is opened direct from the heated shampooing rooms to a cooler apartment, as the plunge bath chamber. The bather standing in a line between the doorways may then feel a cold draught. To guard against this, double doors, with a small lobby between, should be provided to any means of communication with a cold chamber.
A set of hot rooms could be constructed so that the bather would be in the top current of air that flows from the heating apparatus. By reference to Fig. 11 the reader will understand that by the provision of a platform or grating midway between the floor and ceiling this end would be attained.
The atmosphere of the sudatorium must be perfectly free from vapour.
"Perfect dryness of the air," says Mr. Urquhart, "is indispensable to the enduring of a high temperature.... This dryness is further requisite for electrical isolation. With vapour in the chamber an atmosphere is created injurious to health and conducive to disease. It is the very condition in which low, putrid, and typhus fevers flourish. The electrical spark will not ignite in such an atmosphere, and the magnet will lose its attractive power. We all know the difference of our own sensations on a dry and on a damp day."
CHAPTER VI.
WATER FITTINGS AND APPLIANCES.
The water-fittings of a Turkish bath include a boiler of some form for heating the water, a cold-water cistern, and a hot-water tank; supply-pipes, flow and return pipes, and branch pipes; lavatorium fittings, comprising bowls, basins, and c.o.c.ks; douche room fittings, as the "needle" bath, shower, douche, spray, and "wave" baths; a warm shower-bath for bathers entering the bath, or desiring such a shower at intervals; and the fittings of the plunge bath. In addition to this there may be required a drinking fountain in the tepidarium, and an ornamental fountain in the frigidarium; lavatories in various positions; and, possibly, fittings and appliances for the laundry.
Premising an ample supply of pure water, it must be brought into the building through a water-meter to the cold water cistern, which should be at a sufficiently high level to obtain a good "head." This cistern must be capacious and properly connected, on the ordinary circulating principle, with a hot water tank and boiler. Of suitable boilers there are several in the market, of many and varied designs. Simplicity of construction should be the guide to a selection. The boiler will perhaps its most conveniently placed in the stokery, and have be separate furnace and flue, any scheme for combining the heating of the hot rooms and of the water being out of the question. In small baths, however, the hot-water tank may, for economy"s sake, be placed near the ceiling in the laconic.u.m. Where waste steam can be obtained, a water super-heater, with steam coil, may be employed with advantage; but in the majority of cases the ordinary circulating system will be found the most suitable.
The supply-pipes must be of large section, and indeed, the whole scheme of water-fitting should be liberal. It must be remembered that, in addition to the wants of the lavatorium and douche room, plunge, &c., there will be a large amount of water required for laundry purposes, if washing be done upon the premises.
The cold supply cistern may, by the exigencies of the case, be kept down as low as the ceiling of the bath-rooms, and be placed over some subsidiary apartment. This does not give much pressure of water. For all purposes it is best to have the cistern at a minimum height of about 20 ft. above the draw-off taps and valves of the various bathing appliances. This will ensure a good head of water, and make the douche a formidable affair.
The pipes, unions, tees, valves, and c.o.c.ks should all be of the best description in so important a work as the fitting-up of a public bath.
Ordinary bungling plumbing is here out of place. Lead piping should be discarded for all but very cheap work, and iron employed in its stead, with proper screwed joints, angles, and tees. Should there be sufficient means, _copper_ piping should be employed for anything under 1 in. internal diameter, and gunmetal should be used for unions, &c., and for c.o.c.ks and valves.