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Heating by steam is in many respects more satis factory than by hot-air furnaces, but even this mode of heating has not yet been fully perfected.
In most of the school-buildings that are now heated by steam, the radiators are placed in the rooms to be warmed. When due care is exercised to furnish a liberal supply of radiating surface, a satisfactory amount of heat is usually secured, with a reasonable consumption of fuel; and in the coldest days of winter, when there is a great difference between the temperature of the outside and of the inside air, there is little difficulty in securing a moderate degree of action in the ventiducts. In milder weather the ventilation is necessarily very imperfect.
To insure the safety of the school, the boiler should, if practicable, be located outside of the main building
HOT-WATER HEATING. When air is heated by passing over pipes that contain hot water, or over other surfaces heated by water, it retains its purity and possesses all the substantial advantages of air heated by steam. This mode of heating has already been adopted in a large number of school-houses and other buildings, but it has not yet met with so general favor as steam-heating. The choice between steam and hot water is simply a question of convenience and expense. Neither of these modes of heating, as ordinarily applied, affords good ventilation.
Improved Methods of Heating by Steam and Hot Water.
IMPROVED METHODS OF HEATING BY STEAM AND HOT
The following improved method of heating by steam and hot water, is worthy of special consideration: The heating pipes are brought together in a chamber in the basement of the building. This chamber is supplied by conductors with cold air from the outside of the building, and the heated air passes by conductors from the hot-air chamber into the different rooms, in the same manner as from an ordinary hot-air furnace. The consumption of fuel is somewhat greater than in the buildings heated by pipes which are placed in the rooms to be warmed; but this increased expenditure is mainly owing to the fact that rooms heated by pipes around the walls are of necessity poorly ventilated. The saving is made by heating the air once, and then breathing it over and over; whereas, by the improved arrangement, the air is heated, used once, and then removed by introducing a fresh supply.
This may safely be pronounced one of the best methods of heating school-buildings yet devised, since it secures the requisite degree of heat, furnishes a constant supply of fresh, warm air, and insures a good action of the ventiducts.
Another mode of heating by steam or hot water, combines the two modes already described. A portion of the pipes are placed around the rooms to be warmed, and a portion in the hot-air chamber under
the building. The object of this arrangement is to bring as much of the radiating surface as possible into the rooms, and at the same time secure a satisfactory action of the ventiducts.
The Perkins Heater has a pot for the fire and a hot-air chamber, similar to an ordinary hot-air furnace; but instead of sending the heated air of this chamber into the school-rooms, a large number of metallic tubes are made to pass through the chamber, communicating below with cold-air conductors from without, and above with hot-air conductors to the several rooms; the air being heated as it passes through these tubes, which extend from the bottom to the top of the hot-air chamber. To increase the action of the hot air upon these tubes, open pans of water are placed around the fire-pots, which are constantly sending off vapor or steam into the hot-air chamber. This arrangement furnishes a constant supply of pure air, raised to the proper degree of heat, and secures an efficient action of the ventiducts.
Other furnaces, similar in principle to the Perkins Heater, have also been employed successfully in the heating and ventilation of buildings.
Whatever form of apparatus may be employed, it the air is heated in chambers below, it is important that the rooms should be warmed by the introduction of a large volume of moderately heated air. When air is introduced into a room at a very high
temperature, it rises at once to the top and will not readily mingle with the cold air below. In rooms heated by hot-air furnaces, it is not uncommon to find a difference of fifteen or twenty degrees between the temperature of the upper part of the room and that of the lower.
There are two serious objections to the use of common stoves in schools. The first is the inequality of temperature in different parts of the room. Children sitting near the stove are often obliged to endure a temperature of 75° or 80°, while those more remote are exposed to a temperature of only 55° or 60°. The other principal objection to common stoves, is their lack of ventilating power.
The air surrounding a stove rises as it becomes heated, and the cold air near the floor of the room is drawn toward the stove to supply the place of the air that rises. In this way, the feet of the children are obliged to remain in the coldest air of the room, and the evil is increased by the action of the stove, which is constantly giving this stratum of cold air a greater or less degree of motion.*
* “When a stove stands uninclosed in a room, and without any direct connection with the outer atmosphere, there is a constant current of air toward it from every side of the apartment, both to supply the draft of combustion within the fire-chamber, and to seek contact with the outer surface of the hot plates, and then pass upward in a heated, and consequently more rarefied condition. This current, which is not at all impeded by the ordinary movable screens, owing to their being open below and at the sides, enters Improved Stoves.
To obviate these objections, stoves have been constructed with double cylinders, the space between the cylinders being open at the top and bottom. This secures a constant and rapid flow of air between the cylinders, which is heated in passing, rises to the top of the room, and then diffuses itself like the air that is introduced from a hot-air furnace.
It is obvious that this action will have the effect to distribute in different parts of the room the heat that would otherwise be radiated from the stove to the space immediately around it, and thus remove one of the most serious objections to the use of stoves.
The lower opening of the space between the cylin ders may draw its supply of air directly from the room, or by a little extra expense it may be made to communicate with the air outside of the building.
If the air is carried to this lower opening by conductors from the outside, the stove becomes a ventilating stove. Pure, warm air is constantly introduced by it, and the vitiated air of the room is forced out through the ventiducts.
the apartment at the bottom of the doors and windows, and the chinks and openings in the floor and wash board, passes most strongly close along the floor, where the air is coldest and densest, and thus comes in direct contact with the feet and ankles of the occupants. This effect is extremely unpleasant, at the same time that it is most injurious to health. Children, especially in the country, often enter school with damp feet, and exposure to this cold current of air, in a state of inaction for hours together, is the sure but unsuspected cause of many a severe cold and hard cough.”—Pennsyl: vania School Architecture, by Thomas H. Burrowes, LL. D