Document zzGJVpExOkqDgpGORqXx1mzZ0

HEATING VENTILATINC AIR CONDITIONING GUIDE 1944 wall. They may be covered with wood veneers and decorated to harmonize with other parts of the room, or they may be cast into panels to imitate oak or other wood designs. With flat plate panels it is common practice to use a frame of plaster, wood, metal or composition to allow for expansion. These plates may be heated with either hot water or steam and connected as an ordinary radiator system. See Figs. 5 and 6. 5. By dearie heated metal plates or panels. These plates or panels are either placed in insulated recesses of walls or ceilings or fastened to the construction, as found desirable. They should not have a surface temperature much above 200 F. Some have a much Fig. 6. Flat Type Panel Installed in Wall Recess higher surface temperature but a lower temperature gives a more comfortable condition aimis more'efficient. 6. By electrically heated tapestry mounted on screens and on the wall. For this purpose the screen is woven with an electric continuous conductor. Such screens are useful to plug in at any position for emergency local heating without taking care of a large-room .or office. Note. If all of a heating panel is installed at one end of a large room there may be a marked difference between the equivalent temperature on the two sides of the body. It is usually desirable, therefore, that the heat be distributed at different parts of the walls and ceilings so that no uncomfortable effect will be felt from unequal heating. CALCULATION PRINCIPLES The calculation method for radiant heating as given in the following pages has been used in determining panel areas and temperatures for a number of actual installations in several widely separated areas of the United States. Other methods are being developed by recent investi- 790 CHAPTER 45. RADIANT HEATINC gators2,8 who have given recognition to the fact that MRT and air temperature are interdependent, and that any change in panel surface temperature, outside air temperature, location of heating surface, number of air changes and heat transmission characteristics of the structure will Table 1. Total Radiation to Surroundings at Absolute Zero Boot ob Mean Radiant ATUBE Deg F Radiation in Bto per square foot per hour emitted to summndingB with a tempera ture of absolute aero by bodies at various temperatures and with emissivity factor e e 1.00 0.95 e 0.90 0.80 Body OB Mean Radiant aturb Deg F Radiation in Btu per square foot per hour emitted - to surroundings with a temperature of absolute zero by bodies at various temperatures and with emissivity factor e e 1.00 V 0.95 e0.90 e 0.80 30 99.3 35 103.5 40 107.6 45 112.1 46 112.9 47 113.9 48 114.8 49 115.6 so 116.5 51 117.5 52 118.4 53 119.4 54 120.2 55 121.1 56 122.1 57 123.1 58 124.0 59 124.9 60 .125.8 61 126.6 62 127.7 63 128.6 64 129.6 65 130.5 66 131.6 67 132.5 68 133.5 69 134.5 70 135.5 94.3 98.3 102.4 106.5 107.3 108.2 109.1 109.9 110.6 in.6 112.5 113.4 114.2 115.1 116.0 117.0 117.8 118.6 119.5 120.3 121.4 122.2 123.1 124.0 125.0 125.9 126.8 127.8 128.8 89.4 93.2 96.8 100.9 101.6 102.5 103.4 104.1 104.9 105.8 106.5 107.4 108.2 109.0 109.9 110.9 111.6 112.4 113.4 114.0 114.9 115.8 116.7 117:5 118.4 119.3 120.1 121.1 121.9 79.4 82.8 86.1 89.7 90.4 91.1 91.9 92.4 93.2 94.0 94.7 95.5 96.2 96.9 97.7 98.5 99.2 99.9 100.7 101.4 102.2 102.9 103.7 104.4 105.4 106.0 106.8 107.6 108.4 71 72 73 74 75 80 85 90 100 110 120 130 140 150 160 170 180 190 200 210 220 250 300 350 400 450 500 550 600 136.5 137.4 138.4 139.6 141.0 146.6 152.3 157.9 169.6 181.6 194.8 210.1 223.2 237.1 251.1 270.5 288.0 306.5 325.2 348.0 371.5 437.8 575.0 740.0 942.1, 1176.0 1464.0 1791.0 2405.0 129.6 130.5 131.5 132.6 133.9 139.4 144.6 149.9 161.1 172.5 185.0 190.6 212.1 225.2 238.8 257.0 273.8 291.0 309.0 330.6 353.0 415.9 .546.1 703.0 895.0 1117.0 1390.0 1701.0. 2284.0 122.9 123.6 124.5 125.6 126.9 132.0 137.1 142.1 152.6 163:5 175.4 189.1 201.0 213.5 226.0 243.5 259.1 275.8 292.8 313.1 334.4 394.0 517.5 666.0 847.5 1059.0 1318.0 1613.0 2165.0 109.3 109.9 110.6 111.7 112.8 117.4 121.9 126.4 135.7 145.4 155.9 168.1 178:5 189.7 201.0 216.4 230.4 245.1 260.3 278.4 297.1 350.2 460.0 592.0 753.5 941;0. 1171.0 1434.0 1925.0 These factors are calculated from the formula where / 0.1723 X T* \ 100.000,000 ) q = total radiation, Btu per square foot per hour. e = emissivity. . T = absolute temperature, degrees Fahrenheit. influence the value of the MRT and consequently also influence the air temperature required for optimum comfort. The first step in the calculations for radiant heating of a given room is to determine the desired mean radiant temperature, MRT.; the second, to *Trend Curves for Estimating Performance of Panel Heating Systems, by B. F. Raber and F. W. Hutchinson (A.S.H.V.E. Journal Section. Heating, Piping and Air Conditioning, July, 1942, p. 432). 1Panel Heating and Cooling Analysis by B. F. Raber and F. W. Hutchinson (A.S.H.V.E. Transactions, Vol. 47,1941, p. 285). 791