Document p8wrNpRq5RmDQGOJe19p30ZE

240 Chapter 13 Table 1. Small-Tube Cast-Iron Radiators 1945 Guide . Number op Tubes per Section 3d 4<? 5a 6d Catalog Rating per Section11 Sq Ft 1.6 1.6 1.8 2.0 2.1 2.4 1.6 2.3 3.0 3.7 Section Dimensions A Height In. B Width Minimum Maximum In. In. c Spacing** In. 25 m 3)4 ix 19 4% 4% ix 22 4% 4% m 25 4% 4i% m 22 m 6% i X 25 5Vs -6% ix 14 6% 8 19 6% 8 25 61% 8 32 6% 8 ix m m IX ~D Leg . Height In. 2)4 2)4 2)4 2)4 2)4 2)4 2)4 2)4 2)4 2)4 rci mm \ A 1 A I]. "The square foot of equivalent direct steam radiation is defined as-the ability to emit 240 Btu per hour, with steam at 215 F; in air of 70 F. These ratings apply only to installed radiators exposed in a normal manner;.not to radiators installed behind enclosures, grilles, etc. (See A.S.H.V.E. Code for Testing Radi ators adopted January, 1927.) bLength equals number of sections times \% in. Over-all height and leg height, as produced by some manufacturers, are one inch (1 in.) greater than shown in Columns A and D. Radiators may be furnished without legs. Where greater than standard leg heights are required this dimension shall be 4H in. ' dOr equal. from a wall-type radiator may be reduced from 5 to 10 per cent if the radiator is placed near the ceiling with the bars horizontal and in ail air. temperature exceeding 70 F. When radiators are placed near the ceiling, there is usually such a large difference in the temperature between the floor level and the ceiling that it becomes difficult to heat the living zone of the room satisfactorily. Pipe coils are assemblies of standard pipe or tubing (1 in. to 2 in.) which are used as radiators. In older practice these coils were commonly used in factory buildings, but now wall-type radiators are most frequently used for this service. When coils are used, the miter type assembly Is to be preferred as it best cares for expansion in the pipe. Cast manifolds or headers, known as branch tees, are available for this construction. The heat emission of pipe coils placed vertically on a wall with the pipes horizontal is given in Table 2. This has been developed from avail- Table 2. Heat Emission of Pipe Coils Placed Vertically on a Wall (Pipes Horizontal) Containing Steam at 215 F and Surrounded with Air at 70 F btu per linear foot of coil per hour (not linearfeet of pipe) Size opPifb Single row........... ................---------Two.... ............................ -.......... -........... Four------- ----------------- ---------------------- EighL----------- ------------------------------ -----Ten . .. _________ -- ... -- -- Twelve --.................................................. 1 In. 132 252 440 567 651 732 812 lHIs. 162 312 545 702 796 907 1005 1M If. 185 348 616 793 907 1020 1135 Radiators and Convectors 241 able data and does not represent definite results of tests. For such coils the heat emission varies as the height of the coil. The heat emission of each pipe of ceiling coils, placed horizontally, is about 126 Btu, 156 Btu, and 175 Btu per linear foot of pipe, respectively, for 1-in., lj^-in., and lj^-in. coils. CONVECTORS Cast-iron radiators may be concealed in a cabinet or other enclosure for appearance. In such cases a greater percentage of heat is conveyed to the room by convection thereby resulting in a form of gravity convector. A typical recessed convector is shown in Fig. 1. The heating element consisting of a large percentage of fin surface is usually shallow in depth and placed low in the enclosure in order to produce maximum chimney effect in the enclosure. The air enters the enclosure near the floor line just below the heating element, is moderately heated in passing through the core and delivered to the room through an opening near the top of enclosure.. Since the air can only enter the enclosure at the floor line, the air in the room, which always lies at this level, is constantly being withdrawn and replaced by the warmer air. This air movement accom plishes the desired reduction in temperature differentials and assures maximum comfort in the living zone. Concealed heaters or convectors are generally available as completely built-in units. The enclosing cabinet should be designed with suitable TfKi et 3nC* ou*kt grilles to give the heating element its best performance. 1 ables of capacities are catalogued for various lengths, depths and heights, and combinations are available in several styles for installations, such as tue wall-hung typq, free-standing floor type, recess type set flush with wall or oltset, and the completely concealed type. Most of these types may be )lfra"ged with a top outlet grille in a plane parallel with the floor, although h 6 ou^e* practically standard. In cases where enclosures are to th ut are "ot furnished by the heater manufacturer, it is important at the proportions of the cabinet and the grilles be so designed that they th i-11^ lmPa'r the performance of the assembled convector. It is desirable at the enclosure or housing for the convector fit as snugly as possible