Document 5k9K02BNq8GJ8BvDEY1QY8pnR

522 CHAPTER 22 1951 Guide Table 5. Ratings fob Cast-Ibon Radiant Baseboabd Rating in Btu pkb Linbas Foot Ttpe and Height Radiator Temperature--Fahrenheit 215 210 205 200 195 190 185 180 175 Typo R, Low height.................. 300 285 271 257 245 231 219 206 194 Type R. High height................. 425 404 384 365 347 328 310 292 274 Type RC. Low height............... 500 475 452 429 408 385 365 344 323 Type RC. High height.............. 700 665 633 601 572 540 510 481 452 170 182 258 304 426 marily used in hot water systems, but may also be used in two-pipe steam systems. There are various kinds of baseboard radiation available,1 the radiant type and the convector type. Radiant baseboards have a substantial portion of the front face water backed, and do not depend upon an enclo sure for their heat output. Cast-iron radiant baseboards may be either (1) a full radiant, called Type R, or (2) a radiant convector, called Type RC. The Type RC unit, in addition to the radiant front face, has ex tended convection heating surface on the rear face to increase its output. The convector type of baseboards includes finned tube units with which enclosures are used. The front of the enclosure supplies radiant heat. oThe basic advantage of the baseboard radiator or of the long low narrow radiator is that its normal placement is along the cold walls and under areas where the greatest heat loss occurs in a room. Other advantages claimed for baseboard radiators are: they are inconspicuous; they are clean in operation; they offer a minimum of interference with furniture place ment, and, they distribute the heat near the floor. This last characteristic reduces the floor to ceiling temperature gradient to about 2 F deg, and tends to produce uniform temperatures throughout the room. It also makes baseboard radiators especially adaptable to basementless homes, where cold floors are prevalent.2 Heat loss calculations for baseboard heating systems are the same as those used for other types of radiation. The procedure for designing baseboard heating systems is given in I=B=R Installation Guide No. 5.1 Ratings for baseboard radiation are expressed in Btu per linear foot. The ratings for cast-iron baseboard units have been standardized1 and are given in Table 5. Ratings of finned-tube units are listed in manufacturers' catalogs. A method for establishing ratings of all types of baseboard radiation bn the basis of tests has been developed.3 Pipe coils are assemblies of standard pipe or thbing (1 in. to 2 in.) which are used as radiators. In older practice these coils were commonly used Table 6. Heat Emission of Pipe Coils Placed Vebticallt on a Wall (Pipes Hobizontal) Containing Steam at 215 F and Subbounded with Aib at 70 F Btu per linear fool of coil per hour (not linear feet of pipe) Size or Pipe Single row. . . _____ ... Twq . .................................... Four-- ____ ___ ________ ,, .. ; Six.- . _ ................ .. ...... _... Eight __ ___ .. .. Ten.. .................................;........................ Twelve....... ...... ....... .................. ..... 1 In. 132 ,252 440' 567 651 732 812 IK In. 162 312 545 702 796 907 1005 IK In. 185' 348 616 793 907 1020 1135 Radiators and Convectors 523 in factory buildings, but are not often found in this service today. When 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 6, 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 in 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 Convectors are space heating devices composed of a casing with outlet grille, and an extended surface heating element of fin-tube or cast-iron fin surface. The casing usually contains a damper. The air enters the en closure near the floor line below the heating element, is heated in passing through the element, and delivered to the room through the outlet grille located near the top of the enclosure; The room air movement thus established accomplishes a reduction in floor to ceiling temperature dif ferential, and tends to assure comfort in the living zone. A typical re cessed convector is shown in Fig. 1. Factory-assembled units comprised of a heating element, casing and outlet grille with damper, are widely used. Grilles may be used over the air inlets. 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 convector. 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. Cast-iron heating units may be concealed in a cabinet or 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. The output of a convector, for any given length and depth, is a function of the height of the discharge grille above the heating element. Therefore,