Document N2bobja741kgMv3bNj6QZ45DR

American Society of Heating and Ventilating Engineers Guide, 1934 has adopted the following standards: Code for Testing Radiators (1927); Codes for Testing and Rating Concealed Gravity Type Radiation (Steam, 1932, and Hot Water, 1933). For steam services the actual condensation weight is taken without any allowance for heating effect; for hot water services the weight of circulated water is used without allowance for heating effect. In all cases the total heat transmission varies as the 1.3 power of the temperature difference between that inside the radiator and the air in the room, and is expressed in Btu or Mb per hour. Standard test conditions specify either a steam pressure of 1 lb gage (215 F), or hot water at 170 F and a room temperature of 70 F for radi ators, or an inlet air temperature of 65 F for convectors. The heating capacity of a steam radiator or steam convector is determined as follows: 'where Ht = WJhg (1) Ht = Btu per hour under test conditions. PFS = condensation in lb per hour. Afg = latent heat in Btu per lb. Ht may be converted to standard conditions of code ratings by using the proper correction factor from the following formulae: For radiators: 1 1 /215 - 70V-3 ( 145 y-3 Ta - Tr) (2) For convectors: /215 - 65\l-3 / 150 y-3 \Ta-Ti) \ Ta - Ti) (3) idard conditions will be: where Ha = Ca Ht CB = correction factor. rs = steam temperature during test in degrees Fahrenheit. Tr = room temperature during test in degrees Fahrenheit. Ti = inlet air temperature during test in degrees Fahrenheit. Ha = heat emission rating under standard conditions in Btu per hour. (4) Similarly, for hot water convectors, the output under test conditions may be determined as follows: H =W{8i - e,) where H = Btu per hour under test conditions. W = pounds of water handled during test. 0i = average temperature of inlet water in degrees Fahrenheit. 0, = average temperature of outlet water in degrees Fahrenheit. .1 = duration, of test in seconds. 416 Chapter 30--Radiators and Gravity Convectors To convert test results to standard conditions, the following correction factor is used: (C = 170 - 65 \i ( 105 V 9i - 0 2 (6) It has been shown for the exponent 1.3 that the range of error when it is used is less than 5 per cent7. aSee Mechanical Equipment of Buildings, by Harding and Willard, Vol. I. second edition, 1929. GRAVITY-INDIRECT HEATING SYSTEMS8 The heating units for this system are usually of the extended surface type for steam or hot water, and are installed about as shown in Fig. 8. The temperature and volume of the air leaving the register must'be great enough so that in cooling to room temperature the heat available will just equal the heat loss during the same time. In cases where ventilation is a requirement, the air volume needed may become so large that the entering "Torts of Convectors in a Warm Wall Testing Booth, by A. P. Kratz, M. K. Fahnestock, and E. L. nrodenck (Heating, Piping and Air Conditioning, August, 1933)."'-- - *For further information on this subject see A.S.H.V.E. Code of Minimum Reauirementa for the Heating Ventilation of Buildings "(edition of 1929) and Mechanical Equipment of Buildings,.hy Harding and Willard, Vol. I. second edition, 1929. 417