Install Instructions
99
IM-PR 566442 1114 (Design Manual)
Location
Snowfall
Hours per
Year
Snow-Free
Area Ratio
A
r
Heat Fluxes Not Exceeded During Indicated Percentage
of Snowfall Hours from 1982 through 1993, Btu/h-ft²
b
75% 90% 95% 98% 99% 100%
Albany, NY 156
1
0.5
0
89
60
37
125
86
62
149
110
83
187
138
119
212
170
146
321
276
276
Albuquerque, NM 44
1
0.5
0
70
51
30
118
81
46
168
96
61
191
117
89
242
156
92
393
229
194
Amarillo, TX 64
1
0.5
0
113
71
24
150
88
46
168
108
62
212
124
89
228
142
115
318
305
292
Billings, MT 225
1
0.5
0
112
64
22
164
89
33
187
102
45
212
116
60
237
128
68
340
179
113
Bismarck, ND 158
1
0.5
0
151
83
16
199
107
30
231
124
39
275
148
60
307
165
73
477
243
180
Boise, ID 85
1
0.5
0
58
38
22
79
52
31
100
66
40
126
80
53
146
89
62
203
164
164
Boston, MA 112
1
0.5
0
96
65
37
137
95
75
165
112
93
202
149
121
229
190
172
365
365
365
Buffalo, NY 292
1
0.5
0
115
68
23
166
97
39
210
127
55
277
164
93
330
188
112
570
389
248
Burlington, VT 204
1
0.5
0
91
58
23
130
78
40
154
92
55
184
113
78
200
128
94
343
343
343
Cheyenne, WY 224
1
0.5
0
119
70
16
172
97
37
201
111
52
229
132
77
261
149
100
354
288
285
Chicago, IL, O'Hare
International Airport
124
1
0.5
0
96
58
23
126
77
38
153
94
53
186
113
75
235
137
83
521
265
150
Cleveland, OH 188
1
0.5
0
85
52
23
124
73
37
157
92
47
195
118
69
230
147
92
432
235
225
Colorado Springs, CO 159
1
0.5
0
89
57
23
135
82
45
167
99
61
202
124
87
219
140
112
327
218
165
Columbus, OH,
International Airport
92
1
0.5
0
71
45
15
101
60
30
123
71
45
149
87
60
175
95
62
328
184
135
Des Moines, IA 127
1
0.5
0
120
74
24
174
102
46
208
120
69
255
149
94
289
180
108
414
310
231
Detroit, MI,
Metro Airport
153
1
0.5
0
92
57
23
130
77
38
156
94
47
192
118
75
212
134
89
360
227
194
Duluth, MN 238
1
0.5
0
123
71
22
171
97
32
201
114
46
238
131
68
250
142
77
370
213
196
Ely, NV 153
1
0.5
0
67
44
23
97
66
45
116
83
67
134
111
97
162
129
112
242
241
240
Eugene, OR 18
1
0.5
0
59
47
30
110
77
53
139
93
70
165
119
102
171
122
120
224
164
164
Fairbanks, AK 288
1
0.5
0
91
52
15
121
68
23
144
78
31
174
94
40
202
108
48
391
200
87
Baltimore, MD,
BWI Airport
56
1
0.5
0
87
69
46
139
108
84
172
147
119
235
200
181
282
238
214
431
369
306
Great Falls, MT 233
1
0.5
0
123
71
17
171
93
31
193
107
45
233
129
60
276
144
75
392
210
143
Indianapolis, IN 96
1
0.5
0
95
58
23
134
80
38
158
96
52
194
116
83
215
124
99
284
209
209
Table 5-1. Frequencies of snow-melting surface heat fluxes at steady state conditions.
a
Does not include back and edge heat loss.
32
a. Heat fluxes are at the snow-melting surface only. See text for calculation of back and edge heat loss fluxes.
b. Multiply values by 0.2931 to convert to W/ft²
32. ©ASHRAE Handbook -- Systems and Equipment. Chapter 50, Table 1. 2008.