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674 CHAPTER 49 1959 Guide -------------------:-A----------------- -- ------------------------\------------------- .0 '.* e - ;2U*''o- . -'.O 0 ' 0 ' .0 \-0' }' 0 - f \ 0 * 0 . a- 0. . 0 .. 0 . 0 - -. . - 0 . - . '. . 0 ; V. > q- '0 . / 0 o -? o ? > o \ o \ rrt.L\ P Depth of Finish Coet--Aeustfd uHin-of emmets. Finish Cost may be asphalt bat then cover stab sboold be reduced from I in. Depth of *k vbonld ihnji keep thermal resistance equal to ) in. d 8 Depth required by structural ^***rT% be a of ) in. of Fig. 1 .... Detail of Snow Melting Panel trace quantities about twice as often as there are for meas urable quantities of 0.01 in. or more. It is assumed that th^ light falls can be handled by the idling load. The remaining oohimns of Table 1 represent the frequency distribution of required heat output. This distribution is based on the solution to the basic equation for two values of the free area ratio, Ar . This distribution represents the Tumia of the analysis and is also the hnma for Tables 3 4. For specific conditions, or for cities other than those given in Table 1, the solutions to Equation 2 are given in Table 2. Table 2....Heat Output and Fluid Temperature for Snow-Melting System l,-0f i. = 10F f. = 20 f u - SO F bb of K Snowfall Speed V Speed r Speed V Speed v 5 10 15 5 10 15 5 10 15 5 10 15 0.08 1.0 9* 151 205 260 127 168 209 102 128 154 75 84 94 tm 108 135 162 97 117 138 85 97 110 70 75 79 0.0 9. 66 66 66 64 64 64 62 62 62 60 60 60 tm 66 66 66 65 65 65 64 64 64 63 63 63 0.18 1.0 9. 218 273 327 193 233 274 165 191 217 135 144 154 tm 142 169 198 129 149 170 117 129 142 100 105 109 0.0 4. 133 133 133 129 129 129 125 125 125 121 121 121 tm 99 99 99 97 97 97 95 95 95 93 93 93 0.25 1.0 ?. 292 347 401 265 305 346 235 281 287 203 212 221 tm 179 206 234 165 186 206 151 163 176 134 139 144 0.0 9* ^06 208 208 202 202 202 195 195 195 188 188 188 tm 137 137 137 134 134 134 131 131 131 127 127 127 No**: Thb table is based an a relative humidity of 8} percent far ell air temperetures. " rate of snowfall, inches of water equivalent per hoar. A, -- free area ratio. - slab output, Btu pm (hoar) (square foot). U air temperature, Fahrenheit. tm fluid tentperatme.Fahrenheit. Bered on eonetjmaim -- ahuwn in Fig i s wind speed, miles per boor. Table 3... .Design Data for Three Casses of Snow-Melting System* cay Albuquerque, N. M. Amarillo, Tex. Boston, Mass. Buffalo-Niagara Falla, N. Y. Burlington, Vt. Caribou-Limestone, Me. Cheyenne, Wyo. Chicago, III. Colorado Springs, Colo. Columbus, Ohio Detroit, Mich. Duluth, Minn. Falmouth, Mass. Great Falls, Mont. Hartford, Conn. Lincoln, NebMemphis, Texrn.' Minneapolis-St. Paul, Minn. Mt. Home, Idaho New York, N. Y. Ogden, Utah Oklahoma City, Okla. Philadelphia, Pa. Pittsburgh, Pa. Portland, Ore. Rapid City, S. D. Reno, Nev. St. Louis, Mo. Salina, Han. Sault Ste. Marie, Mich. Seattle-Tacoma, Wash. Spokane, Wash. Washington, D. C. Deapn Output, Bfci per (Hr) (Sq Ff) Gao 1 system1 Ckm 0 Ckm IQ system2 system* 71 82 167 98 143 241 107 231 255 80 192 307 90 142 244 89 (93) 83 89 49 (63) 52 138 129 165 63 72 307 425 350 293 253 69 83 (114) 93 84 (112) 115 140 206 144 138 254 255 374 165 372 260 64 (67) 134 63 (95) 50 121 202 144 155 90 298 246 212 254 140 342 98 216 217 66 81 350 97 229 263 89 157 275 86 97 111 58 (86) 98 122 85 52 (78) 102 154 152 120 144 447 155 198 228 213 92 128 133 87 127 189 117 121 144 From Air Conditioning, Heating and Ventilating, August 1957, p. 92. * Where idling rate is greater than Class I design rate, idling rate is given in parenthesis and should be used as Class I design output. 1 Few Class I (residential) Systems, the design output is ret at that required beat output (me Table 1) when A, 0 at tta nth percentile d the dbtributica; that is where #8% d the boats have this outputor lea. * For does H (oommcitiol) Systems, the put when Ar " 0 in Table 1 (bet column). oatpat is *--,tn*>rnT ouW * For Class HI (industrial) Systems the design output ta determined by the foOowuic four requirements: (1) Output is never *<--for two emaeeutive boon; (S) Output for Af m 1; Table 1, is at least I Btu pm hour per eq ft greater than maximum output for A, -- 0; (S) A, b greater *- cr equal to 04 mum raquiremeat shown la Table 1 for A, - 1. That a,* 4>-Mi (S. + qJ far the eoBditioas where 91 * C + $< + o + q, are a maximum; (4) The free area ratio A, b unity for at least 08% d the hoars Dated m Table 1. Snow Melting 675 Table A .... Yearly Operating Data tdBag MeOtap Idling Meffinq Kate,* Odpvt,* Ste pei Sto per (hr) (year) (*q ft) (sq ft) Time,4 hr per year Out- pot/ Clow* Bta pei (year) (*q ft) Gty Time,1 far per year Rate,* Bln pet (hr) Uq ft) Output,* Bta per (year) (*9 ft) Tone,4 hr per year Out put.* Oust* Btu per (ye) (sq ft) Albuquerque, N. M.. 32.5 29100 22 Amarillo, Tex............ 51.1 48200 33 Boston, Mass............. Buffalo-Niagara Falls, N. Y......................... 52.1 59400 145 50.2 85500 240 Burlington, Vt.. Caribou-limestone, Me............................ 76.9 152000 236 93.0 238000 290 Cheyenne, Wyo.. 77.7 140000 138 Chicago, 111......... Colorado Springs, Colo...................... 1848 67.8 125000 134 1583 63.4 100000 76 Columbus, Ohio 1383 Detroit, Mich.......... 1790 49.0 87600 134 Duluth, Minn............. 2922 113.8 332000 250 Falmouth, Mass-- 1071 44.2 47400 73 Great Falls, Mont.. 1677 111.6 187000 174 Hartford, Conn.... 1412 41.9 59200 171 j 908 II 969 Mt. Home, Idaho-- III 1150 1 2150 11 2520 New York, N. Y....... IN 2770 I 8000 II 9080 Ogden, Utah.............. Ml 9100 I 11800 1 14600 Oklahoma City, Okla. 111 14900 I 11800 li 13500 Philadelphia, Pa....... III 13800 I 17800* 1 20600 Pittsburgh, Pa........... III 22500 I 9730 II 13200 Portland, Ore............ TIT 20200 1 7200 II 8390 Rapid City, S. D.... III 8700 1 3960* II 3960 Reno, Nev.................. 111 7390 1 3590 II TIT 5350 1 5540 TT 6850 Kalina, Han................ ill 7070 1 33200* Sault Ste. Marie, TT 38100 Mich......................... 111 39500 l 3830 Seattle-Tacoma, II 4250 ill 4290 Wash........................ 1 13700* II 15400 Spokane, Wash......... 111 19100 1 9830 II 10800 Washington, D. C__ 111 10810 1546 1532 1655 719 820 1445 221 1873 1510 1398 2512 392 1673 770 41.9 64300 50.7 77700 44.6 73800 56.2 40400 31.4 25700 49.5 71500 17.4 3840 86.4 162000 36.9 55700 44.8 4950 53.9 75400 77.7 195000 17.2 6750 39.1 65500 30.6 23600 40 76 160 44 58 182 36 116 87 33 54 345 44 196 33 I 1260 11 1530 111 1590 1 4180 11 4690 111 4710 I 7050 11 7370 111 7370 I 2380 11 2800 111 5400 1 2710 II 3100 m 3110 1 9050 11 10700 111 11100 1 1300 11 1330 m 1380 1 7450* 11 8250 HI 13400 1 2970 II 3030 111 3030 1 2190 11 2290 HI 2380 1 2920 11 3370 111 3810 I 17600* 11 22200 111 23200 1 1410 11 1430 111 1430 1 8650 11 9350 Hi 9560 1 1650 11 1660 111 1690 Lincoln, Neb.......... 1906 67.2 128000 91 Memphis,- Tens___ Minneapolis-St. Paul, Minn........................ 454 32.0 14500 2570 95.1 244000 11 203 II 8350 III 8520 I 702 11 721 III 792 I 14200* 11 17600 111 18400 t From Table 1, Column I X 8C30 (hr per year). * Rate when idling, Bta per (Hr) (Sq Ft) -- (QJ7* -f 3J) (X) - 0, w tare* TM wind speed freer Column 5, Table 1, a&d 1 -- air temperature from Column 4, Table 1. 1 Product af the two preceding fftlumP* Hoan of Snowfall, from Column 7, Table 1. 1 See footnote far Table X ' Beced an the eendition that surface temperatures maintained at S3 deg until required output axoeedi designed output, at which time design output b need readiest af required oatpat. Distribution af required output hered oa Table 1. * Bared os Idling Rate rather than Design Hate. Atr Conditioning, Heating and Ventilating, August 1957, p. 94. Notice that these solutions are for a relative humidity of 80 percent. For other values of relative humidity, corrections can be obtained by using Equations 8 and 9 as follows: ~ - --Ar(0D201p + 0.055)*,, dp,, (8) (0.020Ip + 0.055)5,, (9) Snow-melting installations are classified in Table 3 ac cording to types as Class 1, II, or III. These classes have been dtsmsaBd thoroughly in Reference 3, and are defined in