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22 MARINE REVIEW. [May 17, MECHANICAL VEN TILATION AND HEATING. BY WALTER B. SNOW.* In the combined process of heating and ventilating, a specific amount of heat is in all cases required to compensate for transmission losses to the colder cutdoor atmosphere, and a certain other quantity to provide for the warming of all air which intentionally or otherwise enters the room from without. The former amount varies with the character of the construction and the difference between indoor and outdoor tempera- tures. It is independent of the volume of air supplied for ventilation. The amount of heat required for tempering the air supply for ventilation alone is directly proportional to its volume, and is that necessary to raise it to the temperature of the room. This is in no way available for heating, but it is all important in securing satisfactory ventilation, which, when prop- erly provided, grows effective in proportion to the expenditure. lt is manifest that air may readily serve as a vehicle for heat for maintaining the desired temperature within an apartment. Evidently the air must be preheated, and therefore the plenum with the blower system, which is that here described, or pressure method of supplying is preferable to the vacuum or exhaust method. All local or direct heating surface is eliminated from the rooms and may be massed in connection with the fan, thereby greatly simplifying the details of installation. The heating surface thus provided almost universally takes the form of a steam coil, built up in sections and enclosed in a steel plate casing through which the air is passed by the action of the fan. The pipes, usually 1 inch in size, are here set 2% inch on centers, thus providing a free area for passage of air equal to about 40 per cent. of the gross area of the face of the section. The air passing through such a heater must be warmed by a contact. The increment due to radiation is In a wooden structure, or in one of brick or stone which is already built, such distribution must be made by means of galvanized iron pipes. The simplest possible arrangement consists of a single upright galvanized iron flue, immediately beneath which the apparatus 1s placed so as to deliver the air directly upward into the base of the flue. Upon each floor the requisite number of outlets are provided, at or near ceiling level and the air discharged therefrom towards the outer walls. As the building becomes more extended in its character it becomes necessary with a single standpipe system to somewhat extend the branches so as to convey the air to a greater distance from the standpipe. The apparatus is here placed in the basement and discharges directly upward into the stand- pipe. Upon the first floor the branch pipe is extended and subdivided so as to heat the individual offices on that floor, while upon the other floors the horizontal branch is only of moderate length. In a long very slight. Therefore the arrangement of pipes which thoroughly breaks up all currents best serves the purpose by insuring intimate and constantly changing contact. The compactness of this construction is shown by the fact that within the space measured by 6 feet in length, 7 feet in height and 7% inches in thickness there may 'be massed nearly 1,000 lineal feet of 1-inch pipe. Such construction readily lends itself to manifold arrangements in connection with fans of various types. The most important feature of this type of combined heating and ventilating apparatus, familiarly known as a hot-blast apparatus, lies in the fact that the rapid movement of air across the heated surfaces renders them vastly more efficient than when exposed in still air. In other words, far less surface is required for the same heat trans- mission. In a hot blast apparatus consisting of a fan and heater like that illustrated herewith the heat transmission when the . > air velocity is 1,200 feet per minute is on the average about ea 10 B. T. U., or over five times as much ag in the case of di- rect radiation. That is, a hot blast apparatus need contain only one-fifth the surface required to secure a given result with direct radiation. The design and manner of application of such an apparatus, and the method of air distribution employed in this system must of necessity depend upon the character cf the building, its surroundings and its uses. The ordinary structure devoted to manufacturing purposes presents the simplest of all problems. As a rule the per capita space for the opera- tives is large, and the heating is to be considered as of paramount im- portance, while the ventilation, although sufficient with the blower system, is in a sense incidental. STURTEVANT HEATING APPARATUS WITH THREE-QUARTER HOUSING STEAM FAN by allowing the fan to draw its supply from the building itself, thereby simply turning the air over and over, and merely adding to it the heat necessary te offset the transmission and leakage losses. To this end it is most desirable that the apparatus be placed as near the center of the building as possible, so that the air may be drawn back to it from all sides. Such location also simplifies the distributing system and re- duces the cost. From the apparatus the air may be conducted by under- ground ducts or overhead pipes to its proper destination. In buildings of more than one story the simplest arrangement for heating consists in placing the apparatus on the lower floor or in the basement, and delivering the air into one or more vertical flues from which it'is discharged through suitable outlets upon the several floors. _ *Abstract of a lecture delivered at Cornell University. Mr. Snow is of the en- gineering staff of the B. F. Sturtevant Co., Boston. . - In fact, ample ventilation may usually be:secured I APPLICATION OF THE BLOWER SYSTEM OF HEATING AND VENTILATION. building in which a single standpipe is adhered to a greater extent of the piping system on each floor may 'be made. Thus the standnvipe may be carried up outside of the building, but thoroughly protected, and the horizontal pipes on the various floors kept 'comparatively near the wall. In a new brick building convenience can be secured by distributing the air from one or more brick flues built against the wall of the build- ing. If these are provided in sufficient number they require no distri- buting pipe connections, but if economy is squght by providing a single flue, then it becomes necessary 1o obtain satisfactory distribution on each floor i11 some such marner as is shown in the illustration, in which an individual system is provided at the ceiling of each floor. Where the building is of less extent a special deflecting outlet may be placed upon me opening in the flue on each floor and serve to effectually distribute the air. In a new brick building of reasonable size the best arrangement con- sists in building a series of pilaster flues against the outer wall along one side of the building, from each of which the air is discharged toward the opposite side through openings at eight or more feet above the floor. The apparatus is usually placed in the basement, near the center of the building, and discharges the air into a duct running along one side of the building, and communicating with the tbases of the flues. These flues add but little to the cost of the building. Each opening or outlet is provided with a special form of damper which serve the double purpose of deflecting the air toward the room when open and of preventing ad- mission when closed. The equality of temperature maintained by this system is evidenced by the accompanying average results and readings taken at random from a record kept at the west weave shed of the Pacific Mills, Lawrence, Mass.: Tones veoh: rs & MIDDLE A D 4 ATE TIME. Bast oe West Hnd- | poor. | Heh |Ceiting | End. a 1889. Degrees | Degrees.| Degrees. | Degrees.| Degrees.| Per Cent. Heb. 7. 9.15 A. M. 70 70 70 71 68 65 Hebe 7 es 1.15 P. M. 68 69 68 70 66 64 Feb. 7 6.15 P. M. 70 Tl U1 72 66 65 Heb. S$. = 6.45 A. M. 70 69 71 73 66 61 Rep 8 2.45 P. M. 73 74 75 76 72 68 Hen Go 7.95 A.M. 70 69 71 72 66 75 Feb. 11 10.30 A. M. 68 68 69 68 68 75 Ben, i 5.30 P. M. 72 72 73 72 69 63 Average... 70.12! 70.25] 72.25] 71.75! 67.641 67.12 The particular features of this combined system of ventilation and heating may be thus summarized: The entire heating surface is centrally located, enclosed in a fireproof casing and placed under the control of a