// CODE SNIPPET
Section G2428 (504) Sizing of Category I Appliance Venting Systems
JUMP TO FULL CODE CHAPTER
The following definitions apply to the tables in this section.
APPLIANCE CATEGORIZED VENT DIAMETER/AREA. The minimum vent area/diameter permissible for Category I appliances to maintain a nonpositive vent static pressure when tested in accordance with nationally recognized standards.
FAN-ASSISTED COMBUSTION SYSTEM. An appliance equipped with an integral mechanical means to either draw or force products of combustion through the combustion chamber or heat exchanger.
FAN Min. The minimum input rating of a Category I fan-assisted appliance attached to a vent or connector.
FAN Max. The maximum input rating of a Category I fan-assisted appliance attached to a vent or connector.
NAT Max. The maximum input rating of a Category I draft-hood-equipped appliance attached to a vent or connector.
FAN + FAN. The maximum combined appliance input rating of two or more Category I fan-assisted appliances attached to the common vent.
FAN + NAT. The maximum combined appliance input rating of one or more Category I fan-assisted appliances and one or more Category I draft-hood-equipped appliances attached to the common vent.
NA. Vent configuration is not allowed due to potential for condensate formation or pressurization of the venting system, or not applicable due to physical or geometric restraints.
NAT + NAT.The maximum combined appliance input rating of two or more Category I draft-hood-equipped appliances attached to the common vent.
The application of Tables G2428.2(1) and G2428.2(2) shall be subject to the requirements of Sections G2428.2.1 through G2428.2.17.
TABLE G2428.2(1) [504.2(1)]
TYPE B DOUBLE-WALL GAS VENT
Number of Appliances | Single |
Appliance Type | Category I |
Appliance Vent Connection | Connected directly to vent |
HEIGHT (H) (feet) | LATERAL (L) (feet) | VENT DIAMETER—(D) inches | ||||||||||||||||||||
3 | 4 | 5 | 6 | 7 | 8 | 9 | ||||||||||||||||
APPLIANCE INPUT RATING IN THOUSANDS OF BTU/H | ||||||||||||||||||||||
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | |||||||||
Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
6 | 0 | 0 | 78 | 46 | 0 | 152 | 86 | 0 | 251 | 141 | 0 | 375 | 205 | 0 | 524 | 285 | 0 | 698 | 370 | 0 | 897 | 470 |
2 | 13 | 51 | 36 | 18 | 97 | 67 | 27 | 157 | 105 | 32 | 232 | 157 | 44 | 321 | 217 | 53 | 425 | 285 | 63 | 543 | 370 | |
4 | 21 | 49 | 34 | 30 | 94 | 64 | 39 | 153 | 103 | 50 | 227 | 153 | 66 | 316 | 211 | 79 | 419 | 279 | 93 | 536 | 362 | |
6 | 25 | 46 | 32 | 36 | 91 | 61 | 47 | 149 | 100 | 59 | 223 | 149 | 78 | 310 | 205 | 93 | 413 | 273 | 110 | 530 | 354 | |
8 | 0 | 0 | 84 | 50 | 0 | 165 | 94 | 0 | 276 | 155 | 0 | 415 | 235 | 0 | 583 | 320 | 0 | 780 | 415 | 0 | 1,006 | 537 |
2 | 12 | 57 | 40 | 16 | 109 | 75 | 25 | 178 | 120 | 28 | 263 | 180 | 42 | 365 | 247 | 50 | 483 | 322 | 60 | 619 | 418 | |
5 | 23 | 53 | 38 | 32 | 103 | 71 | 42 | 171 | 115 | 53 | 255 | 173 | 70 | 356 | 237 | 83 | 473 | 313 | 99 | 607 | 407 | |
8 | 28 | 49 | 35 | 39 | 98 | 66 | 51 | 164 | 109 | 64 | 247 | 165 | 84 | 347 | 227 | 99 | 463 | 303 | 117 | 596 | 396 | |
10 | 0 | 0 | 88 | 53 | 0 | 175 | 100 | 0 | 295 | 166 | 0 | 447 | 255 | 0 | 631 | 345 | 0 | 847 | 450 | 0 | 1,096 | 585 |
2 | 12 | 61 | 42 | 17 | 118 | 81 | 23 | 194 | 129 | 26 | 289 | 195 | 40 | 402 | 273 | 48 | 533 | 355 | 57 | 684 | 457 | |
5 | 23 | 57 | 40 | 32 | 113 | 77 | 41 | 187 | 124 | 52 | 280 | 188 | 68 | 392 | 263 | 81 | 522 | 346 | 95 | 671 | 446 | |
10 | 30 | 51 | 36 | 41 | 104 | 70 | 54 | 176 | 115 | 67 | 267 | 175 | 88 | 376 | 245 | 104 | 504 | 330 | 122 | 651 | 427 | |
15 | 0 | 0 | 94 | 58 | 0 | 191 | 112 | 0 | 327 | 187 | 0 | 502 | 285 | 0 | 716 | 390 | 0 | 970 | 525 | 0 | 1,263 | 682 |
2 | 11 | 69 | 48 | 15 | 136 | 93 | 20 | 226 | 150 | 22 | 339 | 225 | 38 | 475 | 316 | 45 | 633 | 414 | 53 | 815 | 544 | |
5 | 22 | 65 | 45 | 30 | 130 | 87 | 39 | 219 | 142 | 49 | 330 | 217 | 64 | 463 | 300 | 76 | 620 | 403 | 90 | 800 | 529 | |
10 | 29 | 59 | 41 | 40 | 121 | 82 | 51 | 206 | 135 | 64 | 315 | 208 | 84 | 445 | 288 | 99 | 600 | 386 | 116 | 777 | 507 | |
15 | 35 | 53 | 37 | 48 | 112 | 76 | 61 | 195 | 128 | 76 | 301 | 198 | 98 | 429 | 275 | 115 | 580 | 373 | 134 | 755 | 491 | |
20 | 0 | 0 | 97 | 61 | 0 | 202 | 119 | 0 | 349 | 202 | 0 | 540 | 307 | 0 | 776 | 430 | 0 | 1,057 | 575 | 0 | 1,384 | 752 |
2 | 10 | 75 | 51 | 14 | 149 | 100 | 18 | 250 | 166 | 20 | 377 | 249 | 33 | 531 | 346 | 41 | 711 | 470 | 50 | 917 | 612 | |
5 | 21 | 71 | 48 | 29 | 143 | 96 | 38 | 242 | 160 | 47 | 367 | 241 | 62 | 519 | 337 | 73 | 697 | 460 | 86 | 902 | 599 | |
10 | 28 | 64 | 44 | 38 | 133 | 89 | 50 | 229 | 150 | 62 | 351 | 228 | 81 | 499 | 321 | 95 | 675 | 443 | 112 | 877 | 576 | |
15 | 34 | 58 | 40 | 46 | 124 | 84 | 59 | 217 | 142 | 73 | 337 | 217 | 94 | 481 | 308 | 111 | 654 | 427 | 129 | 853 | 557 | |
20 | 48 | 52 | 35 | 55 | 116 | 78 | 69 | 206 | 134 | 84 | 322 | 206 | 107 | 464 | 295 | 125 | 634 | 410 | 145 | 830 | 537 | |
30 | 0 | 0 | 100 | 64 | 0 | 213 | 128 | 0 | 374 | 220 | 0 | 587 | 336 | 0 | 853 | 475 | 0 | 1,173 | 650 | 0 | 1,548 | 855 |
2 | 9 | 81 | 56 | 13 | 166 | 112 | 14 | 283 | 185 | 18 | 432 | 280 | 27 | 613 | 394 | 33 | 826 | 535 | 42 | 1,072 | 700 | |
5 | 21 | 77 | 54 | 28 | 160 | 108 | 36 | 275 | 176 | 45 | 421 | 273 | 58 | 600 | 385 | 69 | 811 | 524 | 82 | 1,055 | 688 | |
10 | 27 | 70 | 50 | 37 | 150 | 102 | 48 | 262 | 171 | 59 | 405 | 261 | 77 | 580 | 371 | 91 | 788 | 507 | 107 | 1,028 | 668 | |
15 | 33 | 64 | NA | 44 | 141 | 96 | 57 | 249 | 163 | 70 | 389 | 249 | 90 | 560 | 357 | 105 | 765 | 490 | 124 | 1,002 | 648 | |
20 | 56 | 58 | NA | 53 | 132 | 90 | 66 | 237 | 154 | 80 | 374 | 237 | 102 | 542 | 343 | 119 | 743 | 473 | 139 | 977 | 628 | |
30 | NA | NA | NA | 73 | 113 | NA | 88 | 214 | NA | 104 | 346 | 219 | 131 | 507 | 321 | 149 | 702 | 444 | 171 | 929 | 594 | |
50 | 0 | 0 | 101 | 67 | 0 | 216 | 134 | 0 | 397 | 232 | 0 | 633 | 363 | 0 | 932 | 518 | 0 | 1,297 | 708 | 0 | 1,730 | 952 |
2 | 8 | 86 | 61 | 11 | 183 | 122 | 14 | 320 | 206 | 15 | 497 | 314 | 22 | 715 | 445 | 26 | 975 | 615 | 33 | 1,276 | 813 | |
5 | 20 | 82 | NA | 27 | 177 | 119 | 35 | 312 | 200 | 43 | 487 | 308 | 55 | 702 | 438 | 65 | 960 | 605 | 77 | 1,259 | 798 | |
10 | 26 | 76 | NA | 35 | 168 | 114 | 45 | 299 | 190 | 56 | 471 | 298 | 73 | 681 | 426 | 86 | 935 | 589 | 101 | 1,230 | 773 | |
15 | 59 | 70 | NA | 42 | 158 | NA | 54 | 287 | 180 | 66 | 455 | 288 | 85 | 662 | 413 | 100 | 911 | 572 | 117 | 1,203 | 747 | |
20 | NA | NA | NA | 50 | 149 | NA | 63 | 275 | 169 | 76 | 440 | 278 | 97 | 642 | 401 | 113 | 888 | 556 | 131 | 1,176 | 722 | |
30 | NA | NA | NA | 69 | 131 | NA | 84 | 250 | NA | 99 | 410 | 259 | 123 | 605 | 376 | 141 | 844 | 522 | 161 | 1,125 | 670 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
TABLE G2428.2(2) [504.2(2)]
TYPE B DOUBLE-WALL GAS VENT
Number of Appliances | Single |
Appliance Type | Category I |
Appliance Vent Connection | Single-wall metal connector |
HEIGHT (H) (feet) | LATERAL (L) (feet) | VENT DIAMETER—(D) inches | ||||||||||||||||||||||||||
3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 12 | ||||||||||||||||||||
APPLIANCE INPUT RATING IN THOUSANDS OF BTU/H | ||||||||||||||||||||||||||||
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | 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 | Min | Max | Max | ||
6 | 0 | 38 | 77 | 45 | 59 | 151 | 85 | 85 | 249 | 140 | 126 | 373 | 204 | 165 | 522 | 284 | 211 | 695 | 369 | 267 | 894 | 469 | 371 | 1,118 | 569 | 537 | 1,639 | 849 |
2 | 39 | 51 | 36 | 60 | 96 | 66 | 85 | 156 | 104 | 123 | 231 | 156 | 159 | 320 | 213 | 201 | 423 | 284 | 251 | 541 | 368 | 347 | 673 | 453 | 498 | 979 | 648 | |
4 | NA | NA | 33 | 74 | 92 | 63 | 102 | 152 | 102 | 146 | 225 | 152 | 187 | 313 | 208 | 237 | 416 | 277 | 295 | 533 | 360 | 409 | 664 | 443 | 584 | 971 | 638 | |
6 | NA | NA | 31 | 83 | 89 | 60 | 114 | 147 | 99 | 163 | 220 | 148 | 207 | 307 | 203 | 263 | 409 | 271 | 327 | 526 | 352 | 449 | 656 | 433 | 638 | 962 | 627 | |
8 | 0 | 37 | 83 | 50 | 58 | 164 | 93 | 83 | 273 | 154 | 123 | 412 | 234 | 161 | 580 | 319 | 206 | 777 | 414 | 258 | 1,002 | 536 | 360 | 1,257 | 658 | 521 | 1,852 | 967 |
2 | 39 | 56 | 39 | 59 | 108 | 75 | 83 | 176 | 119 | 121 | 261 | 179 | 155 | 363 | 246 | 197 | 482 | 321 | 246 | 617 | 417 | 339 | 768 | 513 | 486 | 1,120 | 743 | |
5 | NA | NA | 37 | 77 | 102 | 69 | 107 | 168 | 114 | 151 | 252 | 171 | 193 | 352 | 235 | 245 | 470 | 311 | 305 | 604 | 404 | 418 | 754 | 500 | 598 | 1,104 | 730 | |
8 | NA | NA | 33 | 90 | 95 | 64 | 122 | 161 | 107 | 175 | 243 | 163 | 223 | 342 | 225 | 280 | 458 | 300 | 344 | 591 | 392 | 470 | 740 | 486 | 665 | 1,089 | 715 | |
10 | 0 | 37 | 87 | 53 | 57 | 174 | 99 | 82 | 293 | 165 | 120 | 444 | 254 | 158 | 628 | 344 | 202 | 844 | 449 | 253 | 1,093 | 584 | 351 | 1,373 | 718 | 507 | 2,031 | 1,057 |
2 | 39 | 61 | 41 | 59 | 117 | 80 | 82 | 193 | 128 | 119 | 287 | 194 | 153 | 400 | 272 | 193 | 531 | 354 | 242 | 681 | 456 | 332 | 849 | 559 | 475 | 1,242 | 848 | |
5 | 52 | 56 | 39 | 76 | 111 | 76 | 105 | 185 | 122 | 148 | 277 | 186 | 190 | 388 | 261 | 241 | 518 | 344 | 299 | 667 | 443 | 409 | 834 | 544 | 584 | 1,224 | 825 | |
10 | NA | NA | 34 | 97 | 100 | 68 | 132 | 171 | 112 | 188 | 261 | 171 | 237 | 369 | 241 | 296 | 497 | 325 | 363 | 643 | 423 | 492 | 808 | 520 | 688 | 1,194 | 788 | |
15 | 0 | 36 | 93 | 57 | 56 | 190 | 111 | 80 | 325 | 186 | 116 | 499 | 283 | 153 | 713 | 388 | 195 | 966 | 523 | 244 | 1,259 | 681 | 336 | 1,591 | 838 | 488 | 2,374 | 1,237 |
2 | 38 | 69 | 47 | 57 | 136 | 93 | 80 | 225 | 149 | 115 | 337 | 224 | 148 | 473 | 314 | 187 | 631 | 413 | 232 | 812 | 543 | 319 | 1,015 | 673 | 457 | 1,491 | 983 | |
5 | 51 | 63 | 44 | 75 | 128 | 86 | 102 | 216 | 140 | 144 | 326 | 217 | 182 | 459 | 298 | 231 | 616 | 400 | 287 | 795 | 526 | 392 | 997 | 657 | 562 | 1,469 | 963 | |
10 | NA | NA | 39 | 95 | 116 | 79 | 128 | 201 | 131 | 182 | 308 | 203 | 228 | 438 | 284 | 284 | 592 | 381 | 349 | 768 | 501 | 470 | 966 | 628 | 664 | 1,433 | 928 | |
15 | NA | NA | NA | NA | NA | 72 | 158 | 186 | 124 | 220 | 290 | 192 | 272 | 418 | 269 | 334 | 568 | 367 | 404 | 742 | 484 | 540 | 937 | 601 | 750 | 1,399 | 894 | |
20 | 0 | 35 | 96 | 60 | 54 | 200 | 118 | 78 | 346 | 201 | 114 | 537 | 306 | 149 | 772 | 428 | 190 | 1,053 | 573 | 238 | 1,379 | 750 | 326 | 1,751 | 927 | 473 | 2,631 | 1,346 |
2 | 37 | 74 | 50 | 56 | 148 | 99 | 78 | 248 | 165 | 113 | 375 | 248 | 144 | 528 | 344 | 182 | 708 | 468 | 227 | 914 | 611 | 309 | 1,146 | 754 | 443 | 1,689 | 1,098 | |
5 | 50 | 68 | 47 | 73 | 140 | 94 | 100 | 239 | 158 | 141 | 363 | 239 | 178 | 514 | 334 | 224 | 692 | 457 | 279 | 896 | 596 | 381 | 1,126 | 734 | 547 | 1,665 | 1,074 | |
10 | NA | NA | 41 | 93 | 129 | 86 | 125 | 223 | 146 | 177 | 344 | 224 | 222 | 491 | 316 | 277 | 666 | 437 | 339 | 866 | 570 | 457 | 1,092 | 702 | 646 | 1,626 | 1,037 | |
15 | NA | NA | NA | NA | NA | 80 | 155 | 208 | 136 | 216 | 325 | 210 | 264 | 469 | 301 | 325 | 640 | 419 | 393 | 838 | 549 | 526 | 1,060 | 677 | 730 | 1,587 | 1,005 | |
20 | NA | NA | NA | NA | NA | NA | 186 | 192 | 126 | 254 | 306 | 196 | 309 | 448 | 285 | 374 | 616 | 400 | 448 | 810 | 526 | 592 | 1,028 | 651 | 808 | 1,550 | 973 | |
30 | 0 | 34 | 99 | 63 | 53 | 211 | 127 | 76 | 372 | 219 | 110 | 584 | 334 | 144 | 849 | 472 | 184 | 1,168 | 647 | 229 | 1,542 | 852 | 312 | 1,971 | 1,056 | 454 | 2,996 | 1,545 |
2 | 37 | 80 | 56 | 55 | 164 | 111 | 76 | 281 | 183 | 109 | 429 | 279 | 139 | 610 | 392 | 175 | 823 | 533 | 219 | 1,069 | 698 | 296 | 1,346 | 863 | 424 | 1,999 | 1,308 | |
5 | 49 | 74 | 52 | 72 | 157 | 106 | 98 | 271 | 173 | 136 | 417 | 271 | 171 | 595 | 382 | 215 | 806 | 521 | 269 | 1,049 | 684 | 366 | 1,324 | 846 | 524 | 1,971 | 1,283 | |
10 | NA | NA | NA | 91 | 144 | 98 | 122 | 255 | 168 | 171 | 397 | 257 | 213 | 570 | 367 | 265 | 777 | 501 | 327 | 1,017 | 662 | 440 | 1,287 | 821 | 620 | 1,927 | 1,234 | |
15 | NA | NA | NA | 115 | 131 | NA | 151 | 239 | 157 | 208 | 377 | 242 | 255 | 547 | 349 | 312 | 750 | 481 | 379 | 985 | 638 | 507 | 1,251 | 794 | 702 | 1,884 | 1,205 | |
20 | NA | NA | NA | NA | NA | NA | 181 | 223 | NA | 246 | 357 | 228 | 298 | 524 | 333 | 360 | 723 | 461 | 433 | 955 | 615 | 570 | 1,216 | 768 | 780 | 1,841 | 1,166 | |
30 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 389 | 477 | 305 | 461 | 670 | 426 | 541 | 895 | 574 | 704 | 1,147 | 720 | 937 | 1,759 | 1,101 | |
50 | 0 | 33 | 99 | 66 | 51 | 213 | 133 | 73 | 394 | 230 | 105 | 629 | 361 | 138 | 928 | 515 | 176 | 1,292 | 704 | 220 | 1,724 | 948 | 295 | 2,223 | 1,189 | 428 | 3,432 | 1,818 |
2 | 36 | 84 | 61 | 53 | 181 | 121 | 73 | 318 | 205 | 104 | 495 | 312 | 133 | 712 | 443 | 168 | 971 | 613 | 209 | 1,273 | 811 | 280 | 1,615 | 1,007 | 401 | 2,426 | 1,509 | |
5 | 48 | 80 | NA | 70 | 174 | 117 | 94 | 308 | 198 | 131 | 482 | 305 | 164 | 696 | 435 | 204 | 953 | 602 | 257 | 1,252 | 795 | 347 | 1,591 | 991 | 496 | 2,396 | 1,490 | |
10 | NA | NA | NA | 89 | 160 | NA | 118 | 292 | 186 | 162 | 461 | 292 | 203 | 671 | 420 | 253 | 923 | 583 | 313 | 1,217 | 765 | 418 | 1,551 | 963 | 589 | 2,347 | 1,455 | |
15 | NA | NA | NA | 112 | 148 | NA | 145 | 275 | 174 | 199 | 441 | 280 | 244 | 646 | 405 | 299 | 894 | 562 | 363 | 1,183 | 736 | 481 | 1,512 | 934 | 668 | 2,299 | 1,421 | |
20 | NA | NA | NA | NA | NA | NA | 176 | 257 | NA | 236 | 420 | 267 | 285 | 622 | 389 | 345 | 866 | 543 | 415 | 1,150 | 708 | 544 | 1,473 | 906 | 741 | 2,251 | 1,387 | |
30 | NA | NA | NA | NA | NA | NA | NA | NA | NA | 315 | 376 | NA | 373 | 573 | NA | 442 | 809 | 502 | 521 | 1,086 | 649 | 674 | 1,399 | 848 | 892 | 2,159 | 1,318 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
These venting tables shall not be used where obstructions, as described in Section G2427.15, are installed in the venting system. The installation of vents serving listed appliances with vent dampers shall be in accordance with the appliance manufacturer's instructions or in accordance with the following:
- The maximum capacity of the vent system shall be determined using the "NAT Max" column.
- The minimum capacity shall be determined as if the appliance were a fan-assisted appliance, using the "FAN Min" column to determine the minimum capacity of the vent system. Where the corresponding "FAN Min" is "NA," the vent configuration shall not be permitted and an alternative venting configuration shall be utilized.
Where the vent size determined from the tables is smaller than the appliance draft hood outlet or flue collar, the smaller size shall be permitted to be used provided that all of the following requirements are met:
- The total vent height (H) is not less than 10 feet (3048 mm).
- Vents for appliance draft hood outlets or flue collars 12 inches (305 mm) in diameter or smaller are not reduced more than one table size.
- Vents for appliance draft hood outlets or flue collars larger than 12 inches (305 mm) in diameter are not reduced more than two table sizes.
- The maximum capacity listed in the tables for a fan-assisted appliance is reduced by 10 percent (0.90 × maximum table capacity).
- The draft hood outlet is greater than 4 inches (102 mm) in diameter. Do not connect a 3-inch-diameter (76 mm) vent to a 4-inch-diameter (102 mm) draft hood outlet. This provision shall not apply to fan-assisted appliances.
Single-appliance venting configurations with zero (0) lateral lengths in Tables G2428.2(1) and G2428.2(2) shall not have elbows in the venting system. Single-appliance venting configurations with lateral lengths include two 90-degree (1.57 rad) elbows. For each additional elbow up to and including 45 degrees (0.79 rad), the maximum capacity listed in the venting tables shall be reduced by 5 percent. For each additional elbow greater than 45 degrees (0.79 rad) up to and including 90 degrees (1.57 rad), the maximum capacity listed in the venting tables shall be reduced by 10 percent. Where multiple offsets occur in a vent, the total lateral length of all offsets combined shall not exceed that specified in Tables G2428.2(1) and G2428.2(2).
Zero (0) lateral (L) shall apply only to a straight vertical vent attached to a top outlet draft hood or flue collar.
Sea-level input ratings shall be used when determining maximum capacity for high-altitude installation. Actual input, derated for altitude, shall be used for determining minimum capacity for high-altitude installation.
For appliances with more than one input rate, the minimum vent capacity (FAN Min) determined from the tables shall be less than the lowest appliance input rating, and the maximum vent capacity (FAN Max/NAT Max) determined from the tables shall be greater than the highest appliance rating input.
Listed corrugated metallic chimney liner systems in masonry chimneys shall be sized by using Table G2428.2(1) or G2428.2(2) for Type B vents with the maximum capacity reduced by 20 percent (0.80 × maximum capacity) and the minimum capacity as shown in Table G2428.2(1) or G2428.2(2). Corrugated metallic liner systems installed with bends or offsets shall have their maximum capacity further reduced in accordance with Section G2428.2.3. The 20-percent reduction for corrugated metallic chimney liner systems includes an allowance for one long-radius 90-degree (1.57 rad) turn at the bottom of the liner.
Connections between chimney liners and listed double-wall connectors shall be made with listed adapters designed for such purpose.
Where the vertical vent has a larger diameter than the vent connector, the vertical vent diameter shall be used to determine the minimum vent capacity, and the connector diameter shall be used to determine the maximum vent capacity. The flow area of the vertical vent shall not exceed seven times the flow area of the listed appliance categorized vent area, flue collar area, or draft hood outlet area unless designed in accordance with approved engineering methods.
Tables G2428.2(1) and G2428.2(2) shall be used only for chimneys and vents not exposed to the outdoors below the roof line. A Type B vent or listed chimney lining system passing through an unused masonry chimney flue shall not be considered to be exposed to the outdoors. Where vents extend outdoors above the roof more than 5 feet (1524 mm) higher than required by Figure G2427.6.4, and where vents terminate in accordance with Section G2427.6.4, Item 2, the outdoor portion of the vent shall be enclosed as required by this section for vents not considered to be exposed to the outdoors or such venting system shall be engineered. A Type B vent shall not be considered to be exposed to the outdoors where it passes through an unventilated enclosure or chase insulated to a value of not less than R-8.
Corrugated vent connectors shall be not smaller than the listed appliance categorized vent diameter, flue collar diameter, or draft hood outlet diameter.
Vent connectors shall not be increased in size more than two sizes greater than the listed appliance categorized vent diameter, flue collar diameter or draft hood outlet diameter.
In a single run of vent or vent connector, different diameters and types of vent and connector components shall be permitted to be used, provided that all such sizes and types are permitted by the tables.
Draft hood conversion accessories for use with masonry chimneys venting listed Category I fan-assisted appliances shall be listed and installed in accordance with the manufacturer's instructions for such listed accessories.
Interpolation shall be permitted in calculating capacities for vent dimensions that fall between the table entries.
Extrapolation beyond the table entries shall not be permitted.
Where the actual height of a vent falls between entries in the height column of the applicable table in Tables G2428.2(1) and G2428.2(2), either interpolation shall be used or the lower appliance input rating shown in the table entries shall be used for FAN Max and NAT Max column values and the higher appliance input rating shall be used for the FAN Min column values.
The application of Tables G2428.3(1) through G2428.3(4) shall be subject to the requirements of Sections G2428.3.1 through G2428.3.24.
TABLE G2428.3(1) [504.3(1)]
TYPE B DOUBLE-WALL VENT
Number of Appliances | Two or more |
Appliances Type | Category I |
Appliances Vent Connection | Type B double-wall connector |
VENT CONNECTOR CAPACITY | |||||||||||||||||||||||||
VENT HEIGHT (H) (feet) | CONNECTOR RISE (R) (feet) | TYPE B DOUBLE-WALL VENT AND CONNECTOR DIAMETER—(D) inches | |||||||||||||||||||||||
3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | ||||||||||||||||||
APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU/H | |||||||||||||||||||||||||
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | 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 | ||
6 | 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 | |
8 | 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 | |
10 | 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 | |
15 | 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 | |
20 | 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 | |
30 | 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 |
COMMON VENT CAPACITY | |||||||||||||||||||||
VENT HEIGHT (H) (feet) | TYPE B DOUBLE-WALL COMMON VENT DIAMETER (D)—inches | ||||||||||||||||||||
4 | 5 | 6 | 7 | 8 | 9 | 10 | |||||||||||||||
COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU/H | |||||||||||||||||||||
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 | 1,035 | 826 | 640 |
30 | 152 | 138 | 118 | 244 | 210 | 185 | 361 | 297 | 266 | 547 | 459 | 360 | 720 | 585 | 470 | 979 | 808 | 605 | 1,209 | 975 | 740 |
50 | 167 | 153 | 134 | 279 | 244 | 214 | 421 | 353 | 310 | 641 | 547 | 423 | 854 | 706 | 550 | 1,164 | 977 | 705 | 1,451 | 1,188 | 860 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
TABLE G2428.3(2) [504.3(2)]
TYPE B DOUBLE-WALL VENT
Number of Appliances | Two or more |
Appliances Type | Category I |
Appliances Vent Connection | Single-wall metal connector |
VENT CONNECTOR CAPACITY | |||||||||||||||||||||||||
VENT HEIGHT (H) (feet) | CONNECTOR RISE (R) (feet) | SINGLE-WALL METAL VENT CONNECTOR DIAMETER—(D) inches | |||||||||||||||||||||||
3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | ||||||||||||||||||
APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU/H | |||||||||||||||||||||||||
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | 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 | ||
6 | 1 | NA | NA | 26 | NA | NA | 46 | NA | NA | 71 | NA | NA | 102 | 207 | 223 | 140 | 262 | 293 | 183 | 325 | 373 | 234 | 447 | 463 | 286 |
2 | NA | NA | 31 | NA | NA | 55 | NA | NA | 85 | 168 | 182 | 123 | 215 | 251 | 167 | 271 | 331 | 219 | 334 | 422 | 281 | 458 | 524 | 344 | |
3 | NA | NA | 34 | NA | NA | 62 | 121 | 131 | 95 | 175 | 198 | 138 | 222 | 273 | 188 | 279 | 361 | 247 | 344 | 462 | 316 | 468 | 574 | 385 | |
8 | 1 | NA | NA | 27 | NA | NA | 48 | NA | NA | 75 | NA | NA | 106 | 226 | 240 | 145 | 285 | 316 | 191 | 352 | 403 | 244 | 481 | 502 | 299 |
2 | NA | NA | 32 | NA | NA | 57 | 125 | 126 | 89 | 184 | 193 | 127 | 234 | 266 | 173 | 293 | 353 | 228 | 360 | 450 | 292 | 492 | 560 | 355 | |
3 | NA | NA | 35 | NA | NA | 64 | 130 | 138 | 100 | 191 | 208 | 144 | 241 | 287 | 197 | 302 | 381 | 256 | 370 | 489 | 328 | 501 | 609 | 400 | |
10 | 1 | NA | NA | 28 | NA | NA | 50 | 119 | 121 | 77 | 182 | 186 | 110 | 240 | 253 | 150 | 302 | 335 | 196 | 372 | 429 | 252 | 506 | 534 | 308 |
2 | NA | NA | 33 | 84 | 85 | 59 | 124 | 134 | 91 | 189 | 203 | 132 | 248 | 278 | 183 | 311 | 369 | 235 | 381 | 473 | 302 | 517 | 589 | 368 | |
3 | NA | NA | 36 | 89 | 91 | 67 | 129 | 144 | 102 | 197 | 217 | 148 | 257 | 299 | 203 | 320 | 398 | 265 | 391 | 511 | 339 | 528 | 637 | 413 | |
15 | 1 | NA | NA | 29 | 79 | 87 | 52 | 116 | 138 | 81 | 177 | 214 | 116 | 238 | 291 | 158 | 312 | 380 | 208 | 397 | 482 | 266 | 556 | 596 | 324 |
2 | NA | NA | 34 | 83 | 94 | 62 | 121 | 150 | 97 | 185 | 230 | 138 | 246 | 314 | 189 | 321 | 411 | 248 | 407 | 522 | 317 | 568 | 646 | 387 | |
3 | NA | NA | 39 | 87 | 100 | 70 | 127 | 160 | 109 | 193 | 243 | 157 | 255 | 333 | 215 | 331 | 438 | 281 | 418 | 557 | 360 | 579 | 690 | 437 | |
20 | 1 | 49 | 56 | 30 | 78 | 97 | 54 | 115 | 152 | 84 | 175 | 238 | 120 | 233 | 325 | 165 | 306 | 425 | 217 | 390 | 538 | 276 | 546 | 664 | 336 |
2 | 52 | 59 | 36 | 82 | 103 | 64 | 120 | 163 | 101 | 182 | 252 | 144 | 243 | 346 | 197 | 317 | 453 | 259 | 400 | 574 | 331 | 558 | 709 | 403 | |
3 | 55 | 62 | 40 | 87 | 107 | 72 | 125 | 172 | 113 | 190 | 264 | 164 | 252 | 363 | 223 | 326 | 476 | 294 | 412 | 607 | 375 | 570 | 750 | 457 | |
30 | 1 | 47 | 60 | 31 | 77 | 110 | 57 | 112 | 175 | 89 | 169 | 278 | 129 | 226 | 380 | 175 | 296 | 497 | 230 | 378 | 630 | 294 | 528 | 779 | 358 |
2 | 51 | 62 | 37 | 81 | 115 | 67 | 117 | 185 | 106 | 177 | 290 | 152 | 236 | 397 | 208 | 307 | 521 | 274 | 389 | 662 | 349 | 541 | 819 | 425 | |
3 | 54 | 64 | 42 | 85 | 119 | 76 | 122 | 193 | 120 | 185 | 300 | 172 | 244 | 412 | 235 | 316 | 542 | 309 | 400 | 690 | 394 | 555 | 855 | 482 |
COMMON VENT CAPACITY | |||||||||||||||||||||
VENT HEIGHT (H) (feet) | TYPE B DOUBLE-WALL COMMON VENT DIAMETER—(D) inches | ||||||||||||||||||||
4 | 5 | 6 | 7 | 8 | 9 | 10 | |||||||||||||||
COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU/H | |||||||||||||||||||||
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 | NA | 78 | 64 | NA | 113 | 99 | 200 | 158 | 144 | 304 | 244 | 196 | 398 | 310 | 257 | 541 | 429 | 332 | 665 | 515 | 407 |
8 | NA | 87 | 71 | NA | 126 | 111 | 218 | 173 | 159 | 331 | 269 | 218 | 436 | 342 | 285 | 592 | 473 | 373 | 730 | 569 | 460 |
10 | NA | 94 | 76 | 163 | 137 | 120 | 237 | 189 | 174 | 357 | 292 | 236 | 467 | 369 | 309 | 638 | 512 | 398 | 787 | 617 | 487 |
15 | 121 | 108 | 88 | 189 | 159 | 140 | 275 | 221 | 200 | 416 | 343 | 274 | 544 | 434 | 357 | 738 | 599 | 456 | 905 | 718 | 553 |
20 | 131 | 118 | 98 | 208 | 177 | 156 | 305 | 247 | 223 | 463 | 383 | 302 | 606 | 487 | 395 | 824 | 673 | 512 | 1,013 | 808 | 626 |
30 | 145 | 132 | 113 | 236 | 202 | 180 | 350 | 286 | 257 | 533 | 446 | 349 | 703 | 570 | 459 | 958 | 790 | 593 | 1,183 | 952 | 723 |
50 | 159 | 145 | 128 | 268 | 233 | 208 | 406 | 337 | 296 | 622 | 529 | 410 | 833 | 686 | 535 | 1,139 | 954 | 689 | 1,418 | 1,157 | 838 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
TABLE G2428.3(3) [504.3(3)]
Number of Appliances | Two or more |
Appliances Type | Category I |
Appliances Vent Connection | Type B double-wall connector |
VENT CONNECTOR CAPACITY | |||||||||||||||||||||||||
VENT HEIGHT (H) (feet) | CONNECTOR RISE (R) (feet) | TYPE B DOUBLE-WALL VENT CONNECTOR DIAMETER—(D) inches | |||||||||||||||||||||||
3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | ||||||||||||||||||
APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU/H | |||||||||||||||||||||||||
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | 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 | ||
6 | 1 | 24 | 33 | 21 | 39 | 62 | 40 | 52 | 106 | 67 | 65 | 194 | 101 | 87 | 274 | 141 | 104 | 370 | 201 | 124 | 479 | 253 | 145 | 599 | 319 |
2 | 26 | 43 | 28 | 41 | 79 | 52 | 53 | 133 | 85 | 67 | 230 | 124 | 89 | 324 | 173 | 107 | 436 | 232 | 127 | 562 | 300 | 148 | 694 | 378 | |
3 | 27 | 49 | 34 | 42 | 92 | 61 | 55 | 155 | 97 | 69 | 262 | 143 | 91 | 369 | 203 | 109 | 491 | 270 | 129 | 633 | 349 | 151 | 795 | 439 | |
8 | 1 | 24 | 39 | 22 | 39 | 72 | 41 | 55 | 117 | 69 | 71 | 213 | 105 | 94 | 304 | 148 | 113 | 414 | 210 | 134 | 539 | 267 | 156 | 682 | 335 |
2 | 26 | 47 | 29 | 40 | 87 | 53 | 57 | 140 | 86 | 73 | 246 | 127 | 97 | 350 | 179 | 116 | 473 | 240 | 137 | 615 | 311 | 160 | 776 | 394 | |
3 | 27 | 52 | 34 | 42 | 97 | 62 | 59 | 159 | 98 | 75 | 269 | 145 | 99 | 383 | 206 | 119 | 517 | 276 | 139 | 672 | 358 | 163 | 848 | 452 | |
10 | 1 | 24 | 42 | 22 | 38 | 80 | 42 | 55 | 130 | 71 | 74 | 232 | 108 | 101 | 324 | 153 | 120 | 444 | 216 | 142 | 582 | 277 | 165 | 739 | 348 |
2 | 26 | 50 | 29 | 40 | 93 | 54 | 57 | 153 | 87 | 76 | 261 | 129 | 103 | 366 | 184 | 123 | 498 | 247 | 145 | 652 | 321 | 168 | 825 | 407 | |
3 | 27 | 55 | 35 | 41 | 105 | 63 | 58 | 170 | 100 | 78 | 284 | 148 | 106 | 397 | 209 | 126 | 540 | 281 | 147 | 705 | 366 | 171 | 893 | 463 | |
15 | 1 | 24 | 48 | 23 | 38 | 93 | 44 | 54 | 154 | 74 | 72 | 277 | 114 | 100 | 384 | 164 | 125 | 511 | 229 | 153 | 658 | 297 | 184 | 824 | 375 |
2 | 25 | 55 | 31 | 39 | 105 | 55 | 56 | 174 | 89 | 74 | 299 | 134 | 103 | 419 | 192 | 128 | 558 | 260 | 156 | 718 | 339 | 187 | 900 | 432 | |
3 | 26 | 59 | 35 | 41 | 115 | 64 | 57 | 189 | 102 | 76 | 319 | 153 | 105 | 448 | 215 | 131 | 597 | 292 | 159 | 760 | 382 | 190 | 960 | 486 | |
20 | 1 | 24 | 52 | 24 | 37 | 102 | 46 | 53 | 172 | 77 | 71 | 313 | 119 | 98 | 437 | 173 | 123 | 584 | 239 | 150 | 752 | 312 | 180 | 943 | 397 |
2 | 25 | 58 | 31 | 39 | 114 | 56 | 55 | 190 | 91 | 73 | 335 | 138 | 101 | 467 | 199 | 126 | 625 | 270 | 153 | 805 | 354 | 184 | 1,011 | 452 | |
3 | 26 | 63 | 35 | 40 | 123 | 65 | 57 | 204 | 104 | 75 | 353 | 157 | 104 | 493 | 222 | 129 | 661 | 301 | 156 | 851 | 396 | 187 | 1,067 | 505 |
COMMON VENT CAPACITY | ||||||||||||||||||||||||
VENT HEIGHT (H) (feet) | MINIMUM INTERNAL AREA OF MASONRY CHIMNEY FLUE (square inches) | |||||||||||||||||||||||
12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |||||||||||||||||
COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU/H | ||||||||||||||||||||||||
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 | FAN +FAN | FAN +NAT | NAT +NAT | |
6 | NA | 74 | 25 | NA | 119 | 46 | NA | 178 | 71 | NA | 257 | 103 | NA | 351 | 143 | NA | 458 | 188 | NA | 582 | 246 | 1,041 | 853 | NA |
8 | NA | 80 | 28 | NA | 130 | 53 | NA | 193 | 82 | NA | 279 | 119 | NA | 384 | 163 | NA | 501 | 218 | 724 | 636 | 278 | 1,144 | 937 | 408 |
10 | NA | 84 | 31 | NA | 138 | 56 | NA | 207 | 90 | NA | 299 | 131 | NA | 409 | 177 | 606 | 538 | 236 | 776 | 686 | 302 | 1,226 | 1,010 | 454 |
15 | NA | NA | 36 | NA | 152 | 67 | NA | 233 | 106 | NA | 334 | 152 | 523 | 467 | 212 | 682 | 611 | 283 | 874 | 781 | 365 | 1,374 | 1,156 | 546 |
20 | NA | NA | 41 | NA | NA | 75 | NA | 250 | 122 | NA | 368 | 172 | 565 | 508 | 243 | 742 | 668 | 325 | 955 | 858 | 419 | 1,513 | 1,286 | 648 |
30 | NA | NA | NA | NA | NA | NA | NA | 270 | 137 | NA | 404 | 198 | 615 | 564 | 278 | 816 | 747 | 381 | 1,062 | 969 | 496 | 1,702 | 1,473 | 749 |
50 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 620 | 328 | 879 | 831 | 461 | 1,165 | 1,089 | 606 | 1,905 | 1,692 | 922 |
For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm2, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
TABLE G2428.3(4) [504.3(4)]
Number of Appliances | Two or more |
Appliances Type | Category I |
Appliances Vent Connection | Single-wall connector |
VENT CONNECTOR CAPACITY | |||||||||||||||||||||||||
VENT HEIGHT (H) (feet) | CONNECTOR RISE (R) (feet) | SINGLE-WALL METAL VENT CONNECTOR DIAMETER (D)—inches | |||||||||||||||||||||||
3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | ||||||||||||||||||
APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU/H | |||||||||||||||||||||||||
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | 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 | ||
6 | 1 | NA | NA | 21 | NA | NA | 39 | NA | NA | 66 | 179 | 191 | 100 | 231 | 271 | 140 | 292 | 366 | 200 | 362 | 474 | 252 | 499 | 594 | 316 |
2 | NA | NA | 28 | NA | NA | 52 | NA | NA | 84 | 186 | 227 | 123 | 239 | 321 | 172 | 301 | 432 | 231 | 373 | 557 | 299 | 509 | 696 | 376 | |
3 | NA | NA | 34 | NA | NA | 61 | 134 | 153 | 97 | 193 | 258 | 142 | 247 | 365 | 202 | 309 | 491 | 269 | 381 | 634 | 348 | 519 | 793 | 437 | |
8 | 1 | NA | NA | 21 | NA | NA | 40 | NA | NA | 68 | 195 | 208 | 103 | 250 | 298 | 146 | 313 | 407 | 207 | 387 | 530 | 263 | 529 | 672 | 331 |
2 | NA | NA | 28 | NA | NA | 52 | 137 | 139 | 85 | 202 | 240 | 125 | 258 | 343 | 177 | 323 | 465 | 238 | 397 | 607 | 309 | 540 | 766 | 391 | |
3 | NA | NA | 34 | NA | NA | 62 | 143 | 156 | 98 | 210 | 264 | 145 | 266 | 376 | 205 | 332 | 509 | 274 | 407 | 663 | 356 | 551 | 838 | 450 | |
10 | 1 | NA | NA | 22 | NA | NA | 41 | 130 | 151 | 70 | 202 | 225 | 106 | 267 | 316 | 151 | 333 | 434 | 213 | 410 | 571 | 273 | 558 | 727 | 343 |
2 | NA | NA | 29 | NA | NA | 53 | 136 | 150 | 86 | 210 | 255 | 128 | 276 | 358 | 181 | 343 | 489 | 244 | 420 | 640 | 317 | 569 | 813 | 403 | |
3 | NA | NA | 34 | 97 | 102 | 62 | 143 | 166 | 99 | 217 | 277 | 147 | 284 | 389 | 207 | 352 | 530 | 279 | 430 | 694 | 363 | 580 | 880 | 459 | |
15 | 1 | NA | NA | 23 | NA | NA | 43 | 129 | 151 | 73 | 199 | 271 | 112 | 268 | 376 | 161 | 349 | 502 | 225 | 445 | 646 | 291 | 623 | 808 | 366 |
2 | NA | NA | 30 | 92 | 103 | 54 | 135 | 170 | 88 | 207 | 295 | 132 | 277 | 411 | 189 | 359 | 548 | 256 | 456 | 706 | 334 | 634 | 884 | 424 | |
3 | NA | NA | 34 | 96 | 112 | 63 | 141 | 185 | 101 | 215 | 315 | 151 | 286 | 439 | 213 | 368 | 586 | 289 | 466 | 755 | 378 | 646 | 945 | 479 | |
20 | 1 | NA | NA | 23 | 87 | 99 | 45 | 128 | 167 | 76 | 197 | 303 | 117 | 265 | 425 | 169 | 345 | 569 | 235 | 439 | 734 | 306 | 614 | 921 | 347 |
2 | NA | NA | 30 | 91 | 111 | 55 | 134 | 185 | 90 | 205 | 325 | 136 | 274 | 455 | 195 | 355 | 610 | 266 | 450 | 787 | 348 | 627 | 986 | 443 | |
3 | NA | NA | 35 | 96 | 119 | 64 | 140 | 199 | 103 | 213 | 343 | 154 | 282 | 481 | 219 | 365 | 644 | 298 | 461 | 831 | 391 | 639 | 1,042 | 496 |
COMMON VENT CAPACITY | ||||||||||||||||||||||||
VENT HEIGHT (H) (feet) | MINIMUM INTERNAL AREA OF MASONRY CHIMNEY FLUE (square inches) | |||||||||||||||||||||||
12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |||||||||||||||||
COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU/H | ||||||||||||||||||||||||
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 | FAN +FAN | FAN +NAT | NAT +NAT | |
6 | NA | NA | 25 | NA | 118 | 45 | NA | 176 | 71 | NA | 255 | 102 | NA | 348 | 142 | NA | 455 | 187 | NA | 579 | 245 | NA | 846 | NA |
8 | NA | NA | 28 | NA | 128 | 52 | NA | 190 | 81 | NA | 276 | 118 | NA | 380 | 162 | NA | 497 | 217 | NA | 633 | 277 | 1,136 | 928 | 405 |
10 | NA | NA | 31 | NA | 136 | 56 | NA | 205 | 89 | NA | 295 | 129 | NA | 405 | 175 | NA | 532 | 234 | 171 | 680 | 300 | 1,216 | 1,000 | 450 |
15 | NA | NA | 36 | NA | NA | 66 | NA | 230 | 105 | NA | 335 | 150 | NA | 400 | 210 | 677 | 602 | 280 | 866 | 772 | 360 | 1,359 | 1,139 | 540 |
20 | NA | NA | NA | NA | NA | 74 | NA | 247 | 120 | NA | 362 | 170 | NA | 503 | 240 | 765 | 661 | 321 | 947 | 849 | 415 | 1,495 | 1,264 | 640 |
30 | NA | NA | NA | NA | NA | NA | NA | NA | 135 | NA | 398 | 195 | NA | 558 | 275 | 808 | 739 | 377 | 1,052 | 957 | 490 | 1,682 | 1,447 | 740 |
50 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 612 | 325 | NA | 821 | 456 | 1,152 | 1,076 | 600 | 1,879 | 1,672 | 910 |
For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm2, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
Related Code Sections
Section G2428 Fuel Gas, (504) Sizing of Category I Appliance Venting Systems
permissible for Category I appliances to maintain a nonpositive vent static pressure when tested in accordance with nationally recognized standards. FAN ...
Residential Code 2018 of Kansas > 24 Fuel Gas > G2428 (504) Sizing of Category I Appliance Venting Systems
G2428.2.13 Fuel Gas, (504.2.13) Draft Hood Conversion Accessories
Draft hood conversion accessories for use with masonry chimneys venting listed Category I fan-assisted appliances shall be listed and installed ...
Residential Code 2018 of Kansas > 24 Fuel Gas > G2428 (504) Sizing of Category I Appliance Venting Systems > G2428.2 (504.2) Application of Single-Appliance Vent Tables G2428.2(1) and G2428.2(2) > G2428.2.13 (504.2.13) Draft Hood Conversion Accessories
G2428.2.7 Fuel Gas, (504.2.7) Liner System Sizing and Connections
Listed corrugated metallic chimney liner systems in masonry chimneys shall be sized by using Table G2428.2(1) or G2428.2(2) for Type B vents ...
Residential Code 2018 of Kansas > 24 Fuel Gas > G2428 (504) Sizing of Category I Appliance Venting Systems > G2428.2 (504.2) Application of Single-Appliance Vent Tables G2428.2(1) and G2428.2(2) > G2428.2.7 (504.2.7) Liner System Sizing and Connections
G2428.2.10 Fuel Gas, (504.2.10) Corrugated Vent Connector Size
Corrugated vent connectors shall be not smaller than the listed appliance categorized vent diameter, flue collar diameter, or draft hood ...
Residential Code 2018 of Kansas > 24 Fuel Gas > G2428 (504) Sizing of Category I Appliance Venting Systems > G2428.2 (504.2) Application of Single-Appliance Vent Tables G2428.2(1) and G2428.2(2) > G2428.2.10 (504.2.10) Corrugated Vent Connector Size
G2428.2.11 Fuel Gas, (504.2.11) Vent Connector Size Limitation
Vent connectors shall not be increased in size more than two sizes greater than the listed appliance categorized vent diameter, flue collar ...
Residential Code 2018 of Kansas > 24 Fuel Gas > G2428 (504) Sizing of Category I Appliance Venting Systems > G2428.2 (504.2) Application of Single-Appliance Vent Tables G2428.2(1) and G2428.2(2) > G2428.2.11 (504.2.11) Vent Connector Size Limitation