Document EvB64JB11Bm3vQbDKNj1ELBY0

Fig. 1. Room Temperature Gradients and Steam Condensing Rates for Four j Types of Cast-Iron Radiators with a Common Temperature at the 60-In. Level, 1 Note that the steam condensations are practically the same for all four radiators when the same eit. j temperature of 69 F is maintained at the 60-in. level. additional tests are necessary with varying degrees of superheat to .1 establish accurate comparisons for all types of radiators and convectors*. , HEATING EFFECT For several years the heating effect of radiators has been considered by . engineers in order to use it for the rating of radiators and in the design of heating systems. Heating effect is the useful output of a radiator, in the comfort zone of a room, as related to the total input of the radiator*. ,Cotd room temp in deg F a 6.68 lb Test R-E56. S-tube rad. 6.48 tb Test R-E20.3-tube rad. 6.12 tb Test R-ES8.1-tube panel rad. 55.0 (b Test R-2c. (Bui. 223) wall rad. height above floor in feet Fig 2 Room Temperature Gradients and Steam Condensing Rates for Fouh Types of Cast-Iron Radiators with a Common Temperature at the 30-In. level Note that the steam condensations are different for all four radiators when the same air temperature of 68 F is maintained at the 80-in. level. 'Testa of Radiators with Superheated Steam, by R. C. Carpenter (A.S.H.V.E. Transactions. Vol. 7. 19*The Heating Effect of Radiators, by Dr. Charles Brabbei (A.S.H.V.E. Transactions, Vol. p. 33). A.S.H.V.E. Research Retort No. 962--The Application of the Eupatheoscope for Mea c the Performance of Direct Radiators and Convectors in Terms of Equivalent Temperatme. by A. C. Willard. A. P. Krata and M. K. Fahnestock (A.S.H.V.E. Transactions. Vol. 39. 1933. p. 303). 272 Chapter 14. Radiators and Gravity Convectors results of tests conducted at the University of Illinois are shown in nrl 2* For the four types of radiators shown, the following con- Fies. 1 anu : elusions are given. j The heating effect of a'radiator cannot be judged solely by the amount-of steam condensed w'thio the temperature differentials can be maintained with long, low, c2' iffrect^radiators, than is possible with high, direct radiators. thtn. "If"] reer portion of the floor-to-ceiling temperature differential in a room of v^age ceiling height heated with direct radiators occurs between the floor and the breathing jeve[ (approximately 2 ft-6 in. above floor) is below the breathing line . i Aonrniimately 5 ft-0 in. above floor), and temperatures taken at the breathing level- (app indicative of the actual heating effect of a radiator in the room. The indicating temperature should be taken below the breathing line level. cv; Hivh column radiators placed at the sides of window openings do not produce as fortable heating effects as long, low, direct radiators placed beneath window Fig. 3. Chart Showing the Steam Demand Rate for Heating Up a Cast-Iron Radiator with Free Air Venting and Ample Steam Supply HEATING UP THE RADIATOR AND CONVECTOR The maximum condensation occurs in a heating unit when the steam is first turned on8. Fig. 3 shows a typical curve for the condensation rate in pounds per hour for the time elapsing after steam is turned into a cast^ iron radiator. The data are from tests on old-style column type radiators. In practice the rate of steam supply to the heating unit while heating up is frequently retarded by controlled elimination of air through air valves or traps. Automatic control valves may also retard the supply of steam. Vacuum types of air venting valves may be used to reduce the length of the venting periods. `A.S.H.V.E. Research Report No. 905--Steam Condensation an Inverse Index of Heating Effect, by A. p. Kratz and.M. K. Fahnestock (A.S.H.V.E. Transactions, Vol. 37, 1931. p. 475). `Effect of Two Types of Cast-Iron Steam Radiators in Room Heating, by A. C. Willard and M. K. Fahnestock (Heating, Piping and Air Conditioning, March, 1930, p. 185). The Cooling and Heating Rates of a Room with Different Types of Steam Radiators and Convectors; oy A. p. Kratz, M. K. Fahnestock and E. L. Broderick (A.S.H.V.E. Journal Section, Heating. Piping Air Conditioning, April, 1937, p. 251)." 273 X