Form RGM 433-CV/LN, Mfg No. 177854 (Revision 1), Page 7
Table 1B - Common Vent Capacity
Fan +
Fan
Fan +
Nat
Nat +
Nat
Fan +
Fan
Fan +
Nat
Nat +
Nat
Fan +
Fan
Fan +
Nat
Nat +
Nat
Fan +
Fan
Fan +
Nat
Nat +
Nat
Fan +
Fan
Fan +
Nat
Nat +
Nat
Fan +
Fan
Fan +
Nat
Nat +
Nat
Fan +
Fan
Fan +
Nat
Nat +
Nat
6 92 81 65 140 116 103 204 161 147 309 248 200 404 314 260 547 434 335 672 520 410
8 101 90 73 155 129 114 224 178 163 339 275 223 444 348 290 602 480 378 740 577 465
10 110 97 79 169 141 124 243 194 178 367 299 242 477 377 315 649 522 405 800 627 495
15 125 112 91 195 164 144 283 228 206 427 352 280 556 444 365 753 612 465 924 733 565
20 136 123 102 215 183 160 314 255 229 475 394 310 621 499 405 842 688 523 1035 826 640
30 152 138 118 244 210 185 361 297 266 547 459 360 720 585 470 979 808 605 1209 975 740
50 167 153 134 279 244 214 421 353 310 641 547 423 854 706 550 1164 977 705 1451 1188 860
100 175 163 N/A 311 277 N/A 489 421 N/A 751 658 479 1025 873 625 1408 1215 800 1784 1502 975
H -
Ve n t
Height
(ft)
10" Diameter
Common Vent
Combined
Input Rating of the Appliances in Thousands of BTUH
6" Diameter
Common Vent
7" Diameter
Common Vent
8" Diameter
Common Vent
9" Diameter
Common Vent
4" Diameter
Common Vent
5" Diameter
Common Vent
Common Venting Tables 1 and 2 Apply to Vertical Common Vents of Type B Double-Wall Pipe or a
Masonry Chimney Lined with a Type B or Listed Liner (see Note)
NOTE: If a masonry chimney is lined with a listed corrugated metallic chimney liner system, size by using Table 1 or 2 for Type B vents with the
maximum capacity reduced by 20% (.80 x maximum capacity) and the minimum capacity as listed.
Table 1A - Vent Connector Capacity
Nat Nat Nat Nat Nat Nat Nat Nat
Min Max Max Min Max Max Min Max Max Min Max Max Min Max Max Min Max Max Min Max Max Min Max Max
1 22 37 26 35 66 46 46 106 72 58 164 104 77 225 142 92 296 185 109 376 237 128 466 289
2 23 41 31 37 75 55 48 121 86 60 183 124 79 253 168 95 333 220 112 424 282 131 526 345
3 24 44 35 38 81 62 49 132 96 62 199 139 82 275 189 97 363 248 114 463 317 134 575 386
1 22 40 27 35 72 48 49 114 76 64 176 109 84 243 148 100 320 194 118 408 248 138 507 303
2 23 44 32 36 80 57 51 128 90 66 195 129 86 269 175 103 356 230 121 454 294 141 564 358
3 24 47 36 37 87 64 53 139 101 67 210 145 88 290 198 105 384 258 123 492 330 143 612 402
1 22 43 28 34 78 50 49 123 78 65 189 113 89 257 154 106 341 200 125 436 257 146 542 314
2 23 47 33 36 86 59 51 136 93 67 206 134 91 282 182 109 374 238 128 479 305 149 596 372
3 24 50 37 37 92 67 52 146 104 69 220 150 94 303 205 111 402 268 131 515 342 152 642 417
1 21 50 30 33 89 53 47 142 83 64 220 120 88 298 163 110 389 214 134 493 273 162 609 333
2 22 53 35 35 96 63 49 153 99 66 235 142 91 320 193 112 419 253 137 532 323 165 658 394
3 24 55 40 36 102 71 51 163 111 68 248 160 93 339 218 115 445 286 140 565 365 167 700 444
1 21 54 31 33 99 56 46 157 87 62 246 125 86 334 171 107 436 224 131 552 285 158 681 347
2 22 57 37 34 105 66 48 167 104 64 259 149 89 354 202 110 463 265 134 587 339 161 725 414
3 23 60 42 35 110 74 50 176 116 66 271 168 91 371 228 113 486 300 137 618 383 164 764 466
1 20 62 33 31 113 59 45 181 93 60 288 134 83 391 182 103 512 238 125 649 305 151 802 372
2 21 64 39 33 118 70 47 190 110 62 299 158 85 408 215 105 535 282 129 679 360 155 840 439
3 22 66 44 34 123 79 48 198 124 64 309 178 88 423 242 108 555 317 132 706 405 158 874 494
1 19 71 36 30 133 64 43 216 101 57 349 145 78 477 197 97 627 257 120 797 330 144 984 403
2 21 73 43 32 137 76 45 223 119 59 358 172 81 490 234 100 645 306 123 820 392 148 1014 478
3 22 75 48 33 141 86 46 229 134 61 366 194 83 502 263 103 661 343 126 842 441 151 1043 538
1 18 82 37 28 158 66 40 262 104 53 442 150 73 611 204 91 810 266 112 1038 341 135 1285 417
2 19 83 44 30 161 79 42 267 123 55 447 178 75 619 242 94 822 316 115 1054 405 139 1306 494
3 20 84 50 31 163 89 44 272 138 57 452 200 78 627 272 97 834 355 118 1069 455 142 1327 555
Fan Assist Fan AssistFan AssistFan Assist Fan Assist
20
30
50
Fan Assist
6
8
10
100
Common Vent Tables 1A and 1B - Capacity of Type B Double-Wall Vents with Type B Double-Wall Connectors Serving Two
or More Category I Appliances
NOTE: Category I appliance can be either Category I draft hood-equipped or fan-assisted type but must be approved for common venting.
H -
Vent
Height
(ft)
R - Vent
Connector
Rise (ft)
Fan AssistFan Assist
Input Rating Limits in Thousands of BTUH
15
8" Diameter 9" Diameter 10" Diameter
Type B Double Wall Vent and Connector
3" Diameter 4" Diameter 5" Diameter 6" Diameter 7" Diameter
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