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WARMING AND VENTILATION.
BY ARTHUR Morin,
[Translated for the Smithsonian Institution by Clarence B. Young.]
[Continued from the Smithsonian Report for 1873, p. 318.]
55. Ventilating by means of common fire-places.-Fire-places, though not economical forms of heating-apparatus, produce a very pleasant temperature, and also serve as efficient means of changing the air of occupied apartments.
Natural draught produced simply by the difference between the temperature of the air within the chimney and that without, in many cases, carries off as much as 14,000 cubic feet of air an hour, even when no fire is burning in the fire-place.
With a coal or wood fire of moderate intensity, the amount of air carried off may be as much as 42,000 cubic feet an hour, or 2,200 cubic feet to each pound of wood burned, and 3,200 cubic feet to each pound of coal burned.
But, with this advantage, common fire-places have the serious defect of drawing in, through the joints of doors and windows, currents of cold air, which run to the fire and chill the backs of those sitting there, an effect which is particularly unpleasant when the face is very much warmed by the fire.
The various forms of apparatus in use, which are designed to warm the apartment, and, at the same time, draw in external air to increase the draft and promote combustion, usually have too small flues, and heat the air to 1760, 2120, or more, which, issuing horizontally at about the height of the occupants of the room, becomes at times unendurable. These forms of apparatus have besides the defect of obstructing the lower portion of the smoke-flue, and of reducing the volume of air caried off. Fire-places made on Douglas Galton's system, with the dimensions given in § 13, do not have these objections, and are unexceptionable means of warming and ventilating during the winter.
56. Use of chimneys for summer-ventilation by means of gas-jets.-Cbimpeys may easily be made to serve as ventilators during the summer, or on special occasions, by placing in them an iron or copper pipe furnished with several gas-burners. In the chimney of an ordinary apartment, having an earthen-ware flue 11 inches square and 66 feet high, the amount of air drawn up the chimney to each foot of gas burned will be greater the less gas is burned and the less the temperature in the flue, following pretty nearly the following decreasing series :
These approximate figures may serve to determine the number of 31 feet burners that will be required to produce any desired rate of change of air in an apartment.
When the chimney is much lower than that just mentioned, it will be necessary to correct the calculated volume of air in the proportion of the square roots of the heights of the flues.
The pipe which conveys the gas to the flue may be easily taken away when not in use, and closed by a blind socket.
This mode of ventilation may be employed to advantage in drawing. rooms on reception-days, provided that registers be placed at conven. ient points for the introduction of moderately warm fresh air.
During the summer, the system of ventilating by means of gas.jets will also allow the room to be maintained at a lower temperature than that of the external air, by drawing in the air from clean cellars to replace that carried off.
Example.—The directors' room at the Conservatory of Arts and Trades is ventilated in this way during the summer; and, although the air from the basement is admitted through but a single opening, entirely too small for the purpose, and the doors of the room are constantly being opened, yet the temperature is always 40 lower than the room of the subdirector, which has a precisely similar exposure, but is unventilated, and it is 70 lower than the temperature of the external air in the shade.
57. Auxiliary ventilating-flues. For unusually large gatherings, in addition to the chimneys, additional flues may be cut in the thickness of the front or party walls, in which gas-jets may be used to produce a strong draught. This method has been tried with success in a house in the Champs Élysées, Paris.
58. In these charitable institutions, in addition to securing space and cleanliness, provision should also be made for obtaining an abundant and regular supply of fresh air, without depending upon the irregular opening of windows.
In this respect, all establishments of this kind, even the model one at the International Exhibition, fall far short. They „re warmed by castiron stoves, the imperfections of which were sbown in $16. As an example of what appears proper to be done in such cases, Fig.14.
I will describe the plan carmummulite ried out in the new asylum
in the parish of Saint Ambrose in Paris, the construction of which was intrusted to M. Picq, the architect, (Fig. 14.)
This asylum is intended to za receive fifty babies. There
will also often be twentyfive mothers there at a time, while the attendants and patronesses present will usually add ten persons more.
With these data, the maximum volume of air to be carried off and replaced by fresh may reach the following figures, ($ 40:)
Cubic feet. For 50 babies, (530 cubic feet each per hour).
.. 26, 500 25 visiting mothers, (1,060 cubic feet each per hour). ... .. 26,500 10 attendants, (1,060 cubic feet each per hour)......... .. 10,600
Total amount of air to be changed every hour. ....... 63, 600 or 18 cubic feet in a second.
This amount greatly exceeds the actual requirement, because the regulations of the asylum forbid the presence of the mothers in the main hall. They are received and nurse their children in a special apartment.
The main room is 61 feet long, 24 feet wide, and 15 feet high, having, therefore, a content of about 22,000 cubic feet. With the amount of air mentioned above, the complete change would take place
63600 in = 2.8 times an hour, which is quite sufficient to keep the room
22000 in a healthful condition.
The room is warmed by a hot-air heater, with vertical cast-iron tubes, having altogether about one hundred square feet of heating-surface, communicating with a cold-air duct, which will be described hereafter.
It was intended that this heater should have two chambers : the exterior one, for drying damp linen, carrying the vapor to the chimney; the interior one, opening into the room, for warming dry linen. On account of the expense, these chambers were not made.
There might easily have been placed around tho fire-chamber in this heater hot-water pipes connected with a receiver, in order to furnish a supply of water for domestic use.
In summer, the receiver, which, indeed, might have been placed in
the chimney-flue, could have been heated by a special fire. This useful appendage was given up for the same reason as the other.
The foul air is carried off through ten flues, a, a, a, (Fig. 14,) made in the thickness of the walls. The required velocity of the current being 2.3 feet a second, ($ 50,) the clear sectional area of each flue has been
18 feet fixed at
The size of the openings might then be 1 foot by 9 inches; but, their area being reduced by a register which cuts off about one-third, they bave been made 1 foot square.
These flues open into collecting-flues arranged under the floor on each long side of the building; each of these collectors being able to carry off at a maximum 9 cubic feet a second, with a mean velocity of 3 feet a second, (§ 50.) They have at their mouths a sectional area of 2.7 square feet, being about 19 inches square; but, at the first part, up to where the third down-flue enters, their areas have been reduced each to 1.6 square feet, they being 1 foot by 20 inches.
The transverse collectors, c, c, in which the air should have a velocity of 4 feet a second, ($ 50,) have each a sectional area of only 2 square feet in their transverse portion, being 1 foot four inches by 1 foot 7 inches, and they are but 2 feet 7 inches by 1 foot 7 inches where they enter the chimney, while there they should carry off 18 cubic feet a second.
The chimney, which should carry off 18 cubic feet a second at the velocity of 7 feet a second, ($ 50,) should have the area = 2.57 square feet, or be 1 foot 7 inches by 1 foot 7 inches. It really has a sectional area of 5 square feet, which is larger than necessary. It contains the smoke-flue, and it has, near the bottom, a little grate 10 inches by 10 inches, forming a heater, in which a little coal-fire may be made in mild weather in order to keep up the circulation of air.
The introduction of fresh air is made in accordance with the rules given in $$ 51, 52.
The fresh-air supply for the heater A is obtained by means of a pipe, B, carried from the garden and passing under the floor. At its outer end, this pipe is connected with a sort of chimney connected with a grating to prevent the introduction of foreign bodies.
The air to maintain the draught of the fire is taken from the little room C.
The warm air supplied by the heater passes to the upper room by pipes, d d d, eee, placed under the floor of the attic-room in the line of the building. The construction of the roof did not permit of using only a single pipe, which would have been sufficient. The cold air to be mixed with the warm air is taken in the upper room, where it is deflected toward the pipes by means of slats, so as to be delivered above the warmair pipe d d d.
A shelf fastened to each side-wall at half the height of the longitud. inal pipe e e e secures the separate admission of hot air below and cold air above. It is sufficient that these shelves be 10 or 12 feet long, but they should be made of earthen ware, in order that they may not be too much heated by the action of the air from the heater, which might prevent the entrance of the cold air.
The two pipes for warm and fresh air are 12 iuches by 20 inches. Four openings, 9,9,9,9, placed in the ceiling in the center line of the room, admit the mixture of warm and fresh air with a velocity of about 20 inches a secoud, (88 51, 52,) and in order to allow for the obstruction of the grating they are made 28 inches by 35 inches. Registers are placed at the lower part of the chimney to regulate the amount carried off, and they are also placed in the warm-air and fresh-air pipes so as to obtain the proper mixture.
Such are the simple and inexpensive arrangements which serve to maintain in this asylum a degree of healthfulness superior to that of other establishments of the kind.
59. Results of experiment.- The plan just described was carried out, with a few modifications in details rendered necessary by local conditions and by work previously done. The asylum was opened January 27, 1868, and experiments made there in the first part of February, wbich gave the following results:
Results of experiments made in Saint Ambrose Infant-Asylum. - The inside work of this asylum was not finished till the latter part of January, and the hall was opened on Monday the 27th to the first children that were presented. After three or four days of heating to bring the interior to the proper temperature, the experiments were begun on the 31st January
In the first visit to the hall, it was noticed that the foul air was carried off very well by all the openings, although the velocity appeared considerably greater at those nearest the chimney, as is natural. It would be easy to render the amounts carried off through the openings more uniform, if deemed necessary, by placing a register at each opening and regulating it once for all.
The admission of fresh air is provided for by means of openings in the ceiling, and its velocity does not exceed 18 or 20 inches a second. It can be rendered entirely uniform by partially closing the openings far. thest from the heater, but this is not necessary.
The amount of air admitted into the heater to be warmed may vary greatly according to the intensity of the fire, but, with the very moderate consumption of 57 pounds a day, it was found to be, on the 6th of Feb. ruary, 62,000 cubic feet; and on the 7th of February, 59,000 cubic feet, raised from the external temperature 42°, the usual mean temperature of the winter, to 889, at which it was admitted into the room. The heater, on account of the large dimensions of its chambers, was more than sufficient alone to supply the room in winter with fresh air heated