Document 6R1bV32kBY5oZ0Ed7Deom1r1

American Society of Heating and Ventilating Engineers Guide, 1924-25 RADIATION REQUIRED FOR VARIOUS ROOM TEMPERATURES The following table from the Establishment of Standard Methods of Proportioning Direct Radiation, by James A. Donnelly (Transactions, Vol. 21, p. 535) gives the proportionate heat losses from buildings, the proportionate transmission from direct radiators, and the proportionate radiation required (with steam at 210 deg.) for various room temper atures, when the outside temperature is zero: TABLE 25. EFFECT OF ROOM TEMPERATURE ON HEAT LOSS AND SIZE OF RADIATOR Room Temperaturb Proportionate Loss IN B.t.u. Difference m Temperature Between Radia tor and Room Proportionate Transmission in B.t.u. Room Temperature Proportionate Surface Required Sq. Ft. 35 40 45 50 55 60 65 70f 75 80 85 90 95 100 105 110 115 120 0.50 0.57 0.64 0.71 0.79 0.86 0.93 l.OOf 1.07 1.14 1.21 1.29 1.36 1.43 1.50 1.57 1.64 1.71 175 170 165 160 155 150 145 140f 135 130 125 120 115 110 105 100 95 90 1.34 1.29 1.24 1.19 1.14 1.09 1.05 l.OOf 0.95 0.91 0.87 ' 0.82 0.78 0.74 0.70 0.66 0.62 0.58 35 40 45 50 55 60 65 70f 75 ' 80 85 90 95 100 105 110 115 120 0.37 0.44 0.52 0.60 0.69 0.78 0.89 l.OOf 1.12 1.26 1.40 1.56 1.74 1.93 2.15 2.39 ,2.66 2.95 . t Standard Conditions. Assuming that the rate of heat loss from a building varies directly with the difference be tween the outside temperature and the building temperature, and considering the heat loss for zero outside, 70 deg. inside as the standard, or lOODer cent; the second column shows the proportionate loss of beat from a building when the outside temperature is zero, and the inside temperature is as given in the first column. Assuming that the rate of transmission from a direct radi ator to the air of a building Is in proportion to their difference in temperature, with a variation in the rate of transmission of 2 per cent, greater or less, for each 10 deg. increase or decrease in their temperature difference, and considering 140 deg. differ ence in temperature (steam 210 deg., building 70 deg.) as standard, or 100 per cent trans mission, the second column shows the proportionate trans mission when the difference in temperature is as given in the first column. Assuming that under stand ard conditions of outside tem perature zero, building tempera ture 70 deg., and radiator tem perature 210 deg. (or 140 deg. difference between the radiator and room) the amount of radia tion necessary is 100 per cent, the proportionate amounts of radiation given in the second column are those necessary to heat a building to the tempera tures given in the first column, when the outside temperature is zero. . The amount of surface required for heating is always obtained by dividing the heat loss from the building by the amount of heat transmitted per square foot of radiation. Therefore, as may be seen from the above tables, the proportionate amount of surface required for heating is obtained by dividing the proportionate heat loss from the building by the proportionate transmission of the radiator, in each case. ... The preceding table may be used to find the proportionate amount of radiation necessary to heat a room to any desired inside temperature, other than 70 deg., when the outside minimum temperature is other than zero, and with a radiator temperature other than standard. Find the difference between the outside temperature and the room temperature in 33