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TABLE 5
Vent Connector Capacity
Type B Double−Wall Vents with Type B Double−Wall Connectors
Serving Two or More Category I Appliances
Vent
Height
H
(feet)
Connector
Rise
R
(feet)
Vent and Connector Diameter − D (inches)
3 Inch 4 Inch 5 Inch 6 Inch
Appliance Input Rating in Thousands of Btu Per Hour
MIN MAX MIN MAX MIN MAX MIN MAX
6
1 22 37 35 66 46 106 58 164
2 23 41 37 75 48 121 60 183
3 24 44 38 81 49 132 62 199
8
1 22 40 35 72 49 114 64 176
2 23 44 36 80 51 128 66 195
3 24 47 37 87 53 139 67 210
10
1 22 43 34 78 49 123 65 189
2 23 47 36 86 51 136 67 206
3 24 50 37 92 52 146 69 220
15
1 21 50 33 89 47 142 64 220
2 22 53 35 96 49 153 66 235
3 24 55 36 102 51 163 68 248
20
1 21 54 33 99 46 157 62 246
2 22 57 34 105 48 167 64 259
3 23 60 35 110 50 176 66 271
30
1 20 62 31 113 45 181 60 288
2 21 64 33 118 47 190 62 299
3 22 66 34 123 48 198 64 309
TABLE 6
Common Vent Capacity
Type B Double−Wall Vents with Type B Double−Wall Connectors
Serving Two or More Category I Appliances
Vent
Height
H
(feet)
Common Vent Diameter − D (inches)
4 Inch 5 Inch 6 Inch 7 Inch
Appliance Input Rating in Thousands of Btu Per Hour
FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT
6 92 81 140 116 204 161 309 248
8 101 90 155 129 224 178 339 275
10 110 97 169 141 243 194 367 299
15 125 112 195 164 283 228 427 352
20 136 123 215 183 314 255 475 394
30 152 138 244 210 361 297 547 459