Document BRN1G12mj1L7pwE9YR03vqygo

622 CHAPTER 25 1949 Guide Table 1. Small-Tube Cast-Iron Radiators Number Tubbs PER Section 3d 4d 5d 6d Rating per Section* 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 B Width Minimum Maximum In. In. In. c Spadngb In. , D Leg Height In. l25 3Ye 3H. m 2H 19 4% . 4% X 2^ 22 4% 4% m 25 4% 4'% IX 2)4 22 25 5X m m 654 imK 2J4 m 14 6% 8 19 6`5fs 8 25 6% 8 32 6% 8 \% m IX IX 2)i 2'A m m. i-' 1 ~w i` r1 ri l * The square foot of equivalent direct steam radiation is defined as the ability to emit 240 Btu per hourl with steam at 215 F, in air of 70 F. These ratings apply only to installed radiators exposed, in a norma manner; not to radiators installed behind enclosures, grilles, etc. (See A.S.H.V.E. Code for Testing Radi* ators adopted January, 1927.) * Length equals number of sections times 1} in. Over-all height andleg 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 44 in. Or equal. Practice Recommendation R174-43 for small-tube cast-iron' radiators. Table 1 shows the size and dimensions now being manufactured. Wall radiators are now rated in terms of equivalent square feet, the same as small-tube radiators. Tests have shown that the heat emitted 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 an 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 rooms satis-, factorily. ,, 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 are not often found in this service today. When Table 2. Heat Emission op Pipe Coils Placed Vebticallt on a Wall (Pipes Horizontal) Containing Steam at 215 F and Surrounded with: Air .at 70 F Blu per linear fool of coil per hour (not linear feel of pipe) . SasofPiPB Single row........1___________.________ Twa-- Four-- - Six. ' . ___ Eight-- .. ----- Ten. ______ . __ . ` 1 In. 132 252 440 567 . 651 732 812 Pi In. ` , . 162 312 545 702 796 .907 . 1005 !H1. 185 ' '348 , 616. , 793 907 1020 1135 Radiators, Convectors, Coils 623 coils are used, the. miter type assembly is preferable as it readily permits expansion in the, pipe. The heat emission of pipe coils placed vertically on a wall with the pipes horizontal is given in Table 2 which has been, developed from available 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 l|-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 con sisting 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 heated moderately .in passing through the core and is delivered to the room through an opening near the top of the enclosure. This air movement accomplishes a reduction in temperature differentials and tends to assure maximum comfort in the living zone. Concealed heaters or convectors are generally available as completely built-in units. Combinations are available in several styles for installa tions, such as the wall-hung type, free-standing floor type, recess type set flush with wall or offset, and the completely concealed type. Most of these types may be arranged with a top outlet grille in a plane parallel with the floor, although the front outlet is practically standard. In cases where enclosures are to be used but are not. furnished by the heater manufacturer, it is important, that the proportions of the cabinet and the.grilles be so designed that they will not impair the performance of the assembled con vector. It is desirable that the enclosure or housing for the convector fit as snugly as possible so that the air to be heated cannot by-pass the heating element in'passing through the enclosure.. The output of a convector, for. any given length and depth, is a function ./<