Document QgXko0Y66mRLv3E0RRVL7owK4

560 CHAPTER 23 1955 Guide Table 7. Factobs to Convert 7 = B = R Steam Ratings to Hot Water Ratings at Temperatures Indicated Average Radiator Temperature Factor Average Radiator Temperature Factor' - Average Radiator Temper atubis Factor 150 0.45 155 0.49 160 0.53 165 0.57 170 0.61 175 0.65 180 0.69 185 0.73 190 0.78 195 0.82 200 0.86 205 0.91 210 0.95 215 1.00 220 1.05 entering and leaving water temperatures is used. These laws may be ex pressed as correction factors to change from output under standard ratingtest conditions, to output under other operating conditions. Such factors are given in Table 6. When it is desired to change the output under any test conditions to the, corresponding output under standard code test conditions, the recip rocal form of correction factor may be derived. The equations for steam units are: For radiators For convectors C. = (1) C, (2) The output under standard conditions will be: where B. = CM, C, = correction factor. I, = steam temperature during test, Fahrenheit degrees. t, = room temperature during test, Fahrenheit degrees. ti = inlet air temperature during test, Fahrenheit degrees. H, = heat emission rating under standard conditions, Btu per hour. H, = heat output under test conditions, Btu per hour. (3) The relation between the size of the radiator or convector and the size of the test room will affect the results obtained in a capacity-rating test. The height and location of the radiator and the insulation of the test room axe other important factors that are not specifically regulated by the codes. For a radiator, the finish coat of paint affects the heat output. Oil paints of any color will give about the same results as unpainted black or nisty surfaces, but an aluminum or a bronze paint will reduce the heat emitted by radiation. The net effect may be a reduction of 10 percent or more in the total heat output of the radiator.8'*'10 Radiator enclosures and convector cabinets of proper design may im prove the heat distribution within the room as compared to the heat dis tribution obtained with an unenclosed radiator.-11 Heating Effect For several years the term heating effect has been used to designate th* relation between the useful output of a radiator, in the comfort zone of * room, and the total input as measured by steam condensation or water Radiators and Convectors 561 temperatures.12'13 The application of such a heating effect factor implies that some radiators and convectors use less steam than others for pro ducing equal comfort heating results in the room. All authorities do not agree that the use of heating effect factors are justified. No standard method for evaluating the heating effect of radia tors and convectors and correlating it with comfort has yet been accepted. One method, with test data14 on radiators and convectors, and making use of the eupatheoscope for evaluating the environment produced, has been sug gested by the- University of Illinois. The principle underlying, the eupa theoscope involves the measurement of the heat loss from a sizable body by radiation and convection, when the surface is maintained at some constant temperature. Through the use of this instrument and its calibration curve, non-uniform environments may be referred to uniform environments rm( Mil old room 11 temp in dea Fi III 1 II 5 60 lb convector No. 1 IunL" Itr 554 tb convector No. 22 6.12 tb convector No. 6 i 6-32 lb 5-tube radiator - Temperature m deg F Position No. 3 Position No. \ 30* level Eoonr Drff 30* level Equiv Diff 67.7 66.2 1.5 67.4 65.9 15 662 64.3 3.9 68.0 66-6 14 68.0 65.1 2.9 67.9 67.9 0.0 66-2 66.4 U 2 34 5 6 7 HEIGHT ABOVE aOOR IN FEET Fig. 2. Temperature Gradients and Equivalent Temperatures for Radiator and Convectors with Common 30 in. Level Temperature m which the air and all surrounding surfaces are at the same temperature. The temperatures of the uniform environments are referred to as equivalent temperatures. The Kata thermometer,16 the thermo-integrator,16-17 and the globe 18 thermometer are other instruments which have been used to measure the influence of air temperature, air movement and radiation in an environment. Data given in Fig. 2 show that while the air temperature at the 30-in. 'evel is the same for the three convectors and the one large-tube cast-iron radiator, in position No. 3 in the test room, the equivalent temperature is 1-5 deg lower than the air temperature in the case of the three convectors, Hnv same 38 the air temperature in the case of the radiator. The difference between the minimum and the maximum amount of heat re quired to maintain the common air temperature at the 30-in. level is of the order of 13 percent. In Fig. 3 are shown the results of tests made with the same three convec tors and the one large-tube cast-iron radiator, so adjusted in size that each approximately the same equivalent temperature in the No. 3 position 10 the test room. The difference between the minimum and the maximum