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HEATING VENTILATING AIR CONDITIONING GUIDE 1942 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 (Figs. 4 and 5). 5. By electric 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. SSde adjusting Met damper Second floorair duct Third floor' ^ air duct 1 ___ _ Air ducts in floor space Fig. 3. Diagram of Air Ducts for Floor Heating Fig. 5. Flat Type Panel Installed in Wall Recess They, should not have a surface temperature much above 200 F; some have a- much higher surface temperature but a lower temperature gives a more comfortable condition and is more efficient. 6. By electrically heated tapestry mounted on screens and on the wall. For this purjpose the screen is woven with an electric continuous conductor. Such screens are useful to 804 CHAPTER 45. RADIANT HEATING plug in at any position for emergency local heating without taking care of a large room or office. Note. It all of a heating panel is installed at one end of a large room there may be a marked difference between the BET on the two sides of the body. It is usually desir able, 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 calculations for radiant heating are entirely different from those for convective heating. The purpose of the latter is to determine and compensate for the rate of heat loss from the room, when the air tempera ture is maintained at the desired conditions. Radiant heating, however. Table 1. Total Radiation to Surroundings at Absolute Eero3 Boot ob Mean Radiant Tempeb- ATURE Deg Fahr Radiation in Btu per square foot per hour emitted to surroundings with a tempera* ture of absolute sero by bodies at various temperatures and with emiasivity factor e e ee e 1.00 0.95 0.90 0.80 [ Boor i ob B Mean BRadiant Temper- ATTTHB Deg Fahr Radiation in Btu per square foot per hour emitted to surroundings with a temperature of absolute sero by bodies at various temperatures ami with emismvity factor a .e e e 1.00 0.95 0.90 0.80 30 99.3 94.3 89.4 79.4 71 136.5 129.6 122.9 109.3 35 103.5 98.3 93.2 82.8 72 137.4 130.5 . 123.6 109.9 40 107.6 102.4 96.8 86.1 73 138.4 131.5 124.5 110.6 45 112.1 106.5 100.9 89.7 74 139.6 132.6 125.6 111.7 46 112.9 107.3 101.6 90.4 75 141.0 133.9 126.9 . 112.8 47 113.9 108.2 102.5 91.1 80 146.6 139.4 132.0 117.4 48 114.8 109.1 103.4 91.9 85 152.3 144.6 137.1 121.9 49 115.6 109.9 104.1 92.4 90 157.9 149.9 142.1 126.4 50 116.5 110.6 104.9 . 93.2 100 169.6 161.1 152.6 135.7 51 117.5 111.6 105.8 94.0 no 181.6 172.5 163.5 145.4 52 118.4 112.5 106.5 94.7 120 194.8 185.0 175.4 155.9 53 119.4 113.4 107.4 95.5 130 210.1 199.6 189.1 168.1 54 120.2 114.2 108.2 96.2 140 223.2 212.1 201.0 178.5 55 121.1 115.1 109.0 96.9 150 237.1 225.2 213.5 189.7 56 122.1 116.0 109.9 97.7 160 251.1 238.8 226.0 201.0 57 123.1 117.0 110.9 98.5- 170 270.5 257.0 243.5 216.4 58 124.0 117.8 111.6 99.2 180 288.0 273.8 259.1 230.4 59 124.9 118.6 112.4 99.9 190 306.5 291.0 275.8 245.1 60 125.8 119.5 113.4 100.7 200 325.2 309.0 292.8 260.3 61 126 6 120.3 114.0 101.4 210 348.0 330.6 313.1 278.4 62 127.7 121.4 114.9 102.2 220 -371.5 353.0 334.4 297.1 63 128.6 122.2 115.8 102.9 250 437.8 415.9 394.0 . 350.2 64 129.6 123.1 116.7 103.7 300 575.0 546.1 517.5 460.0 65 130.5 124.0 117.5 104.4 350 740.0 703.0 . 666.0 592.0 66 131.6 125.0 118.4 105.4 400 942.1 895.0 847.5 753.5 67 132.5 125.9 119.3 106.0 450 ' 1176.0 1117.0 1059.0 941.0 68 133.5 126.8 120.1 106.8 500 1464.0 1390.0 1318.0 1171.0 69 134.5 127.8 121.1 107.6 550 1791.0 1701.0 1613.0 1434.0 70 135.5 128.8 121.9 108.4 600 2405.0 2284.0 2165.0 1925.0 aThese factors are calculated from the formula where / 0.1730 X T*\ 5 = ' ( 100.000.000 ) q = total radiation, Btu per square foot per hour. e *= emissivity T -- absolute temperature, degrees Fahrenheit. 805