Heating device

“ For special purposes in connection with machinery various heating devices are required, of which steam and gas are those most universally used. Steam tubes or coils may be carried through any fixed or movable part of a machine. Steam-heated surfaces, such as tables, pans, chambers, &c., steam-jacketed cylinders, and similar contrivances, are much used. Gas jets from perforated tubes, which may be shaped to any required position, are also convenient for dry heat and higher temperatures than can be obtained from steam. ”

“ This will prevent steam from forming, which might injure the system.
Fig. 72. Device for heating
water automatically.
146. Heaters for Tanks. Hot water is lighter than cold. A pipe from the bottom of the tank leads into the heater, passes thru the heating coils and up into the top of the tank (Figs. 73 and 74) . Water from the tank circulates thru this pipe as the hot water rises and the cold water falls in the tank. As the heater is located on a level with the bottom of the tank, cold water seeking this level flows into the pipe and becomes heated (Fig. 76) .
[119] ”

“ Conduction of heat is a commonplace occurrence in our daily lives, in industrial processes, and in nature. If a metal spoon is dipped in a cup of hot coffee, the spoon handle soon becomes warm and then hot—some of the heat in the coffee is conducted along the spoon. Heat from a burner on a stove is conducted through the bottom of utensils to cook food. In a steam engine or hot-water heating system, heat from burning fuel is transferred by conduction through the iron or steel of the boiler to heat water. ”

“ Heaters.—Heaters are used sometimes in cold dressing rooms, in box offices and in other small spaces where other adequate heating arrangements have not been made. The fire hazard incident to the use of electric heaters is considerable and they should be carefully installed according to the rules given below.
From one-half to three watts per cubic foot will be required to heat a room. The quantity of heat necessary to be supplied depends largely upon the ventilation. ”

“ In buildings of the second class, such as residences, office buildings and hotels, we have been, as a rule, satisfied with sufficient heat, and have relied upon such ventilation as is secured by the natural circulation methods. In such buildings, therefore, the system of heating most used is that known as "direct radiation," in which radiators, or some form of radiating surface, are located in each room, and connected by an arrangement of piping to a central source of steam or hot-water supply. ”

“ Some firms have now made percolators and water heaters with fuse-nut or safety fuse devices which melt if overloaded or allowed to heat up without any liquid in them to be heated. You must not let a percolator “perc” without any water in it. People complain more about good percolators because their heating element [11] burns out, either because they do this or because they have it connected up with too many other devices. Even if you do the right thing in these respects, don’t forget to disconnect the electricity by pulling out the plug. ”

“ To regulate the heat it is necessary either to instal a number of small radiators or to divide the radiators into sections, each section controlled by distinct valves; steam may then be admitted to all the sections of the radiator or to any less number of sections as desired. In a hot-water system the heat is given off at a lower temperature and is consequently more agreeable than that yielded by a steam-heating apparatus. The joint most commonly used for hot-water pipes is termed the “rust” joint, which is cheap to make, but unfortunately is inefficient. ”

“ The question of practical efficiency is, therefore, more strictly speaking, only one of effectiveness of surface. That is, of two radiators under exactly the same conditions of temperature and surroundings, that one which has such an arrangement of its surfaces as to give out the most heat per square foot is the most effective, usually called the most efficient. In all tests of radiators, the heat given off is measured by connecting them so that the steam which condenses can be accurately weighed, its pressure, quality and temperature being determined at the same time. ”

“ Heaters are almost universally used in connection with steam fire engines to keep the water hot, and in many cases to keep a few pounds pressure to shorten the time of going to work should the fire be close at hand. This boiler has an advantage for this kind of heating; the circulation is so perfect and free that all the water in it is heated alike ”

“ Heating Unit. The heating unit of a hot-water system is like any stove consisting of a fire pot and grate. Some are adjustable so that different kinds of fuel may be [66] used. A gas burner is sometimes placed in the fire pot and used for heating a furnace, but this is one of the most wasteful ways of using gas. A real gas furnace is much more economical. The fire and heat from the fire circulate around the coils containing the water. If the coils are not constantly kept full of water, they will be injured by the heat. ”

“ Must be heated, where artificial heating is necessary to prevent freezing, by steam or hot-water systems, the heater to be located in a separate building, and no open flames to be permitted within generator enclosures. ”

“ Gas stoves are becoming increasingly popular by reason of the ease with which they can be put in action and made to maintain an even temperature. But the most up-to-date heating apparatus is undoubtedly electrical. Utensils of all sorts are fitted with very thin heating strips (formed by the deposition of precious metals, such as gold, platinum, &c., on exceedingly thin mica sheets) , through which are passed powerful currents from the mains. ”

“ In this event, auxiliary radiators may be placed under that register, and the operation of the heating apparatus greatly facilitated thereby. This plan is superior to a furnace, and can be applied to hot-water or steam apparatus in dwellings. The reason that it is superior to a furnace is that the supply of heat is more uniform. It does not require the constant firing or attention that is necessary in the case of a hot-air furnace. It may be known that the temperature does not change with the pressure of steam or in the same proportion. ”

“ An electric heater comprising a receptacle, containing oil having a high flashing point and means for circulating the same, a resistance conductor immersed in the oil and adapted to heat the same, and a heating system partially within the container and arranged to receive its heat from the circulating oil. ”

“ Heat loss in buildings.—There have been considered in previous chapters the various kinds of radiators in use and the amount of heat given off by them under different conditions; and the subject now approaches a study of the particular way in which the heat is utilized. The object of any heating system is, of course, to maintain a uniform temperature in the building in question, and to do this it is necessary: First, to replace the heat lost by convection and radiation from the windows and walls of the building to the colder surroundings outside ”

“ Tubes for warming are specially effective when dented or buckled in directions at right angles to each other and to the axis of the tube. This form gives the heating water or steam a swirling motion which causes it to part more rapidly with its heat than does a cylindrical tube of the same surface. Gold’s electric heater for street-cars, bath-rooms, and the like, is a spiral of resistant alloy, hung in a light metallic frame, the whole presenting a large surface to the air. Automobiles driven by heat engines require coils of the utmost possible surface whereat cooling can take place ”

“ The heatilator is a built-in recirculating steel unit consisting of metal sides and back to form a heating chamber, adjacent to the fire pit, which draws cold air through a register at each side near the floor and after the air is heated ejects it through similar registers above. ”

“ One necessity, however, is the provision of motive power, very small though it be, to work the fan or otherwise promote a draught.
Electric heating is, however, the method which will probably take precedence over others in all those cases where systems are tried on their actual merits apart from sentiment or usage. The wonderful facility afforded by the electric heating wire for the distribution of a moderate degree of warmth, in exactly the proportions in which it may be needed, gives the electric method an enormous advantage over its rivals. ”

“ Having selected the system of heating to be employed according to the needs of the building in hand, and having proportioned the radiator surface according to the requirements of the various rooms, it then remains to lay out the system of piping and arrange the various details of construction. ”

“ The hot water in the radiators cools and, in cooling, gives up its heat to the rooms and thus warms them.
In hot-water heating systems, fresh air is not brought to the rooms, for the radiators are closed pipes containing hot water. It is largely for this reason that thoughtful people are careful to raise windows at intervals. Some systems of hot-water heating secure ventilation by confining the radiators to the basement, to which cold air from outside is constantly admitted in such a way that it circulates over the radiators and becomes strongly heated. ”

“ As the heat is applied to the inside of the furnace and tubes, it must, therefore, be the inside dimensions which determine the amount of heating surface.
Note.—If we multiply the interior surface of a tube by the intensity of heat applied, and divide the product by the exterior surface, we shall have the intensity at the outside. We also apply more heat to the outside of a tube, which, passing to the inner surface, augments in intensity per unit of area.
The area of the inner fire-box is not all available for heating, but requires to be reduced as follows:—
For the fire-door. ”

“ But it is impracticable to have all the radiators of a system turned on at one time, and the difficulty with such a system is made evident the minute steam is turned into a cold radiator. When the steam comes in contact with a perfectly cold radiator a large amount is condensed at once in heating the cold iron, and as soon as the pressure becomes adjusted this bulk of water flows out of the radiator connection at one time and drops down the vertical pipe. ”

“ The heating is a single-pipe steam system, the heat generated by a boiler in each building. The principal rooms are heated by radiators, with heating risers used elsewhere. The hardware and lighting fixtures are simple and substantial. ”

“ Heating the metal by direct contact from within the metal itself by these heaters, makes a very efficient equipment, as all of the heat generated is immediately transmitted to the metal exactly where it is required, and there is no loss of heat due to faulty conduction. The dynamic thermometer bulb being immersed in the metal adjacent to the heaters and the pump-well, permits of a very close temperature regulation. ”

“ In both the steam and water heating systems the band or collection of pipes in each room may be covered with ornamental radiating plates, or otherwise treated or arranged to render them sightly and effective. In one form of the hot-water system, however, the collection of a mass of pipes in the rooms is dispensed with, and the pipes are massed in an air chamber over or adjacent to the furnace, where they are employed to heat a current of air introduced from the outside, and which heated [Pg 208] pure air is conveyed through the house by flues and registers as in the hot-air furnace system. ”

“ The stream of air is usually accomplished by the use of ordinary chimney draft assisted by the warm products of heating from the heater. The hot air products of combustion pass through a tapered nozzle into the moist air exhaust pipe, and by the speed a suction is created which helps to pull the moist air out of the cabinet and up the chimney.
When you buy a dryer see to it that the exhaust pipe is large so that you will have wind and heat instead of just heat. Air circulation is what you are really buying. ”

“ It does not necessarily require all the exhaust steam—or the whole volume of waste steam passing from the engine to bring the feed water up to the temperature desired, and the larger the heating appliance the smaller proportion is needed—hence heaters are best made with two exits nicely proportioned to avoid back pressure and at the same time utilize enough of the exhaust to heat the feed water. ”

“ In many mills and factories which use condensing engines, and in which, consequently, exhaust steam is not readily available for heating, steam for this purpose is taken direct from the boilers through a reducing pressure valve and used in the heating system at a pressure of 5 to 20 pounds per square inch. ”

“ Electric Heaters.—As almost every store is now provided with electric light service, and electric heaters can be purchased in all sizes on the open market, the interest in this new application of electric heating is universal. All that is necessary is to place a small electric heater in the window in any concealed position, and to connect it with the lighting mains. ”

“ The points to be observed in a proper and efficient hot-air heating system are the following:
(1) The furnace must be of a proper size in proportion to the area of space to be warmed. (2) The [Pg 167] joints and parts of the furnace must be gas-tight. (3) The furnace should be placed on the cold side of the house, and provision made to prevent cellar air from being drawn up into the cold-air box of the furnace. (4) The air for the supply of the furnace must be [Pg 168] gotten from outside, and the source must be pure, above the ground level, and free from contamination of any kind. ”