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American Society of Heating and Ventilating Engineers Guide, 1937 Fig. 1. Plan View Long Throw Supply Outlet Fig. 2. Plan View Short Throw Supply Outlets the possibility of streaking, and to permit induction of air from all sides of the stream. If the stream actually strikes the ceiling, but at a small angle, the throw will be increased somewhat if the ceiling-is smooth. I{ the angle at which the stream hits the ceiling is 20 deg or more, or if the flow along the ceiling is obstructed by panel mouldings or beams, air velocity may be rapidly lost and a decreased throw result. The air stream also should be so directed that it will not strike nearby columns or beams in such a way as to cause misdirection of the air stream or drafts. : Where the room is of irregular shape, as an ell, or where it has an alcoVe in one side, consideration should be given to obtaining satisfactory circulation in these corners. Frequently this cannot be done except by the use of multiple supply outlets. In using multiple outlets, care must be taken that the several air streams do not interfere with each other, until their velocities have been reduced to values which will not cause high turbulence and a drafty condition. Beams and offsets in the ceiling will cause little difficulty when substantially parallel to the direction of flow, unless they are of Considerable depth, but when positioned across the air stream, may cause drafts and failure to secure satisfactory circulation in that portion of the room farthest from the outlet. In the case of a heating installation, down-drafts produced by such obstructions may not be serious, because the air will rapidly lose its downward motion, but the possibility of failure to obtain satisfactory circulation still exists. The Iocation of supply outlets should, if possible, be such as to take advantage of the maximum velocity permissible from a noise standpoint. For instance, the spaces illustrated in Figs. 1 and 2 may be satisfactorily served by either arrangement. However, by taking advantage of the long -C- az Vjv ?5 'l I \c Ji'K ih . X ^ / iN j\ \ --y --/ Fig. 3. Elevation View Ceiling Supply Outlet with Return Wall Outlet 348 Fig. 4. Elevation View Ceiling Supply and Return Outlet Chapter 19--Air Distribution throw, to which the arrangement in Fig. I lends itself, fewer, outlets are required and additional savings are effected in the sheet metal work. In solving the problem of properly conditioning a room of irregular shape, where multiple wall supply grilles are objectionable, a ceiling out let of the type illustrated in Figs. 3 and 4 may very often be the best solution. In choosing the most desirable location for the return air grille, con sideration should be given to its effect on circulation of the air through the room. It is generally true that the return air grille should be placed on the same wall as the supply and near the floor level. This results in a Fig. 5. Elevation View Correctly Located Return Outlet Fig. 6. Elevation View of Improperly Located Return Outlet U-shaped air path (Fig. 5) which covers the room thoroughly. The arrangement shown in Fig. 6 should be avoided, because it tends to create a stagnant section below the supply grille. What would otherwise be an unsatisfactory dead spot in a room may in some instances be taken care of by location of the return air grille near that area (Fig. 7). STANDARDS FOR SATISFACTORY CONDITIONS The most satisfactory air condition cannot bejdefinitely stated for any particular individual without conducting a series of tests with that individual as subject; some persons are less sensitive than others to yariations in temperature, humidity, air velocity, and noise. The best