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216 CHAPTER 13 1960 Guide by heat gain through dry, sprinkled and water covered roofs (ASHVE Transactions, Vol. 46, 1940, p. 231). 11F. C. Houghten, Carl Gutberlet, and A. J. Wahl: ASHVE Research Report No. 1002--Cooling requirements of single rooms in a modern office building (ASHVE Transactions, Vol. 41, 1935, p. 53). 14 J. N. Livermore: Study of actual vs. predicted cooling load on as air conditioning system (ASHVE Transactions, Vol. 49,1943, p. 287). 11F. C. Houghten, E. C. Hach, S. I. Taimuty, and Carl Gutberlet: ASHVE Research Report No. 1195--Heat gain through walls and roofs as affected by solar radiation (ASHVE Transactions, Vol. 48,1942, p.9i). l*J. P. Stewart: Solar heat gain through walls and roofs for cooling load calculations (ASHVE Transactions, Voi. 54, 1948, p. 361). w G. V. Parmelee and W. W. Aubele: ASHVE Research Report No. 1442--Radiant energy emission of atmosphere and ground (ASHVE Transactions, Vol. 58, 1952, p. 85). 11 D. Brunt: Radiation in the atmosphere (Supplement to the Quarterly Journal of the Royal Meteorological Society, Vol. 66,1940). u G. V. Parmelee, W. W. Aubele, and R. G. Huebseher: ASHVE Research Report No. 1333--Measurements of solar heat transmission through flat glass (ASHVE Transactions, Vol. 54,1948, p. 165). ** G. V. Parmelee and W. W. Aubele: ASHVE Research Report No. 1348--Solar and total heat gain through double flat gin** (ASHVE Transactions, Vol. 54,1948, p. 407). "G. V. Parmelee and W. W. Aubele: ASHVE Research Report No. 1374--Solar energy transmittance of eight-inch hollow glass block (ASHVE Transactions, Vol. 55, 1949, p. 435). **G. V. Parmelee and W. W. Aubele: ASHVE Research Report No. 1399--Heat flow through unshaded glass: Design data for use in load calculations (ASHVE Transactions, Vol. 56, 1950, p. 371). ** G. V. Parmelee and W. W. Aubele: ASHVE Research Report No. 1417--Solar energy transmittance of figured rolled glass (ASHVE Transactions, Vol. 57, 1951, p. 209). 14 D. J. Vild and G. V. Parmelee: ASHAE Research Re port No. 1660--Heat gain through glass skylight fenestrations (ASHAE Transactions, Vol. 62, 1956, p. 89). ** G. V. Parmelee and D. J. Vild: ASHVE Research Re port No. 1485--Dtaigu data for slat-type sun shades for use in load estimating (ASHVE Transactions, Vol. 59, p. 403). G. V. Parmelee, W. W. Aubele, and D. J. Vild: ASHVE Re search Report No. 1474--The shading of sunlit glass: An experimental study of slat-type sun shades (ASHVE Trans actions, Vol. 59, 1953, p. 221). G. V. Parmelee and W. W. Aubele: ASHVE Research Report No. 1460--The shading of sunlit glass: An analysis of the effect of uniformly spaced flat opaque slats (ASHVE Transactions, Vol. 58, 1952, p. 337). t( C. S. Leopold: The mechanism of heat'transfer, panel cooling, heat storage (Refrigerating Engineering, July 1947, p. 33). C. S. Leopold: Hydraulic analogue for the solution of problems of thermal storage, radiatioD, convection and con duction (ASHVE Transactions, Vol. 64,1948, p. 389). w C. 0. Mackey and N. R. Gay; Heat gains are not cooling loads (ASHVE Transactions, Vol. 55, 1949, p. 413). ** C. O. Mackey and N. R. Gay: Cooling load from sunlit glass (ASHVE Transactions, Vol. 58,1952, p. 321). ** See Reference 1, p. 8. * C. M. Ashley: Psychrometric factors in the air conditioning estimate (ASHVETransactions, Vol. 55,1949, p. 91). 41 W. G. Darley: Cooler footcandles for air conditioning (ASHVE Transactions. Vol. 46, 1940, p. 367). IES-A5HVE Joint Committee on Lighting and Air Conditioning: Lighting and air conditioning design factors (ASHVE Journal Section, Heating, Piping ana Air Conditioning, September 1941, p. 605). H. M. Sharp: Lighting and air conditioning (Heating and Ventilating, November 1942, p. 36). " Compiled by J. P. Stewart from various sources. CHAPTER 14 RADIATORS, CONVECTORS, BASEBOARD AND FINNED-TUBE UNITS Definitions, Heat Emission, Radiators, Convectors, Baseboard, Finned-Tube, Ratings, Corrections for Non-Standard Conditions, Enclosed Radiators ADIATORS, convectors, baseboard, and finned-tube 1 and 2 are included to provide principal dimensions and R, are the types of heat-distributing units used in steam average ratings. and hot water heating systems to supply heat to a room by The small-tube type radiators, with a spacing of lVi in. radiation and convection. The function of these devices is per section, occupy less space than the older column and the maintenance of the desired mean radiant and air tem large-tube radiators, and are particularly suited for instal peratures in the area. Since heat losses through the various lation in recesses. parts of the structure constantly tend to lower these tem After a study of the demand for various sizes of radiators, peratures, heat distributing units should be so placed and the Institute of Boiler and Radiator Manufacturers, in co regulated that their output will replace the losses when and operation with the Division of Simplified Practice, National where they occur. If 80 percent of the room heat loss occurs Bureau of Standards, established Simplified Practice Recom through a cold wall or window area, then 80 percent of the mendation R174-47, Cast Iron Radiators, for small-tube input should be introduced in or directed toward that area. cast-iron radiators. Table 3 shows the size and dimensions The term radiator is generally confined to sectional cast- now being manufactured. iron radiation. Cast-iron radiator types may be column, Wall radiators are hung from wall brackets and are well large-tube, small-tube, or wall. adapted to use in factory buildings. Tests have shown that The term convector refers to a heat-distributing unit that the heat emitted from a wall-type radiator may be reduced operates with gravity-recirculated room air, is surrounded from 5 to 10 percent if the radiator is placed near the ceil on all sides by an enclosure having an air-inlet opening below ing with the bars horizontal and in an air temperature ex the heating element, and an air-outlet opening above the ceeding 70 F. Installation of wall radiators at the ceiling is heating element. not recommended because the resulting large temperature The terms baseboard and baseboard radiation refer to gradients between floor and ceiling make it difficult to heat steam or water heat-distributing units designed for installa the living zone satisfactorily. Dimensions and beat emission tion along the bottom of the walls replacing the conven rates of wall radiators for normal wall installations are tional baseboard. They operate with gravity-recirculated given in Table 4. room air, and have a substantial portion of their frontal face surface directly exposed to the room. Pipe Coils The term finned-tube refers to steam or water heat-dis tributing units fabricated from metallic tubing with metallic fins bonded to the tube. They operate with gravity-recircu lated room air and are designed for installation without enclosure, or with open-type grilles or covers, or with en closures having top, front, or inclined outlets. Pipe coils are sometimes used in factory buildings and are usually placed under windows or along heavily-exposed walls. The heat emission of such pipe coils may be obtained from Table 5. CONVECTORS HEAT EMISSION Steam or water heat-distributing units emit heat by radia tion and convection. These heat-transfer processes and the factors that affect them are discussed in detail in Chapter 5. In general, those units having a large portion of their heated surface exposed emit a larger portion of heat by radiation than do units having their beating surfaces com pletely or partly concealed from view. The output of a heat-distributing unit is expressed in units of Btu per hr (Btuh), 1000 Btu per hr (MBh), or in square feet equivalent direct radiation (EDR) (eg., 240 Btuh for steam = 1 sq ft EDR). , RADIATORS Column and lafge-tube radiators are no longer manufac tured, but since many of these units are still in use, Tables Convectors are made in a wide variety of depths, sizes, lengths, and enclosure or cabinet types. The basic sizes and types are listed in Simplified Practice Recommendation 23S-50, Convectors. The heating elements are available in fabricated ferrous and non-ferrous metals as well as cast iron. The air enters the enclosure below the heating element, is heated in passing through the element, and leaves the en closure through the outlet grille located above the beating element. Factory-assembled units comprised of a beating element and enclosure are widely used. These may be free standing, wall hung, or recessed, (Fig. 1) and may have outlet grilles and arched inlets or inlet grilles as desired. In cases where cabinets or enclosures are to be used but are not furnished by the manufacturer, it is important that the proportions of the cabinets or enclosures and the grilles be so designed that they will not impair the performance of the assembled convector. It is desirable that the cabinet or 217