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 fanassisted appliance attached to a vent or connector.
FAN Max. The maximum input rating of a Category I fanassisted appliance attached to a vent or connector.
NAT Max. The maximum input rating of a Category I drafthood-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.
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 fanassisted appliance attached to a vent or connector.
FAN Max. The maximum input rating of a Category I fanassisted appliance attached to a vent or connector.
NAT Max. The maximum input rating of a Category I drafthood-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 504.2(1) through 504.2(6) shall be subject to the requirements of Sections 504.2.1 through 504.2.17.
TABLE 504.2(1) TYPE B DOUBLE-WALL GAS VENT
(continued)
TABLE 504.2(1)‒continued TYPE B DOUBLE-WALL GAS VENT
(continued)
TABLE 504.2(1)‒continued TYPE B DOUBLE-WALL GAS VENT
(continued)
TABLE 504.2(1)‒continued TYPE B DOUBLE-WALL GAS VENT
TABLE 504.2(2) TYPE B DOUBLE-WALL GAS VENT
(continued)
TABLE 504.2(2)-continued TYPE B DOUBLE-WALL GAS VENT
TABLE 504.2(3) MASONRY CHIMNEY
(continued)
TABLE 504.2(3)‒continued MASONRY CHIMNEY
TABLE 504.2(4) MASONRY CHIMNEY
(continued)
TABLE 504.2(4)‒continued MASONRY CHIMNEY
TABLE 504.2(5) SINGLE-WALL METAL PIPE OR TYPE B ASBESTOS CEMENT VENT
TABLE 504.2(6) EXTERIOR MASONRY CHIMNEY
TABLE 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 |
(continued)
TABLE 504.2(1)‒continued 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 | ||
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 | |
100 | 0 | NA | NA | NA | 0 | 218 | NA | 0 | 407 | NA | 0 | 665 | 400 | 0 | 997 | 560 | 0 | 1,411 | 770 | 0 | 1,908 | 1,040 |
2 | NA | NA | NA | 10 | 194 | NA | 12 | 354 | NA | 13 | 566 | 375 | 18 | 831 | 510 | 21 | 1,155 | 700 | 25 | 1,536 | 935 | |
5 | NA | NA | NA | 26 | 189 | NA | 33 | 347 | NA | 40 | 557 | 369 | 52 | 820 | 504 | 60 | 1,141 | 692 | 71 | 1,519 | 926 | |
10 | NA | NA | NA | 33 | 182 | NA | 43 | 335 | NA | 53 | 542 | 361 | 68 | 801 | 493 | 80 | 1,118 | 679 | 94 | 1,492 | 910 | |
15 | NA | NA | NA | 40 | 174 | NA | 50 | 321 | NA | 62 | 528 | 353 | 80 | 782 | 482 | 93 | 1,095 | 666 | 109 | 1,465 | 895 | |
20 | NA | NA | NA | 47 | 166 | NA | 59 | 311 | NA | 71 | 513 | 344 | 90 | 763 | 471 | 105 | 1,073 | 653 | 122 | 1,438 | 880 | |
30 | NA | NA | NA | NA | NA | NA | 78 | 290 | NA | 92 | 483 | NA | 115 | 726 | 449 | 131 | 1,029 | 627 | 149 | 1,387 | 849 | |
50 | NA | NA | NA | NA | NA | NA | NA | NA | NA | 147 | 428 | NA | 180 | 651 | 405 | 197 | 944 | 575 | 217 | 1,288 | 787 |
(continued)
TABLE 504.2(1)‒continued 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 | |||||||||||||||||||||||
10 | 12 | 14 | 16 | 18 | 20 | 22 | 24 | ||||||||||||||||||
APPLIANCE INPUT RATING 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 | 0 | 0 | 1,121 | 570 | 0 | 1,645 | 850 | 0 | 2,267 | 1,170 | 0 | 2,983 | 1,530 | 0 | 3,802 | 1,960 | 0 | 4,721 | 2,430 | 0 | 5,737 | 2,950 | 0 | 6,853 | 3,520 |
2 | 75 | 675 | 455 | 103 | 982 | 650 | 138 | 1,346 | 890 | 178 | 1,769 | 1,170 | 225 | 2,250 | 1,480 | 296 | 2,782 | 1,850 | 360 | 3,377 | 2,220 | 426 | 4,030 | 2,670 | |
4 | 110 | 668 | 445 | 147 | 975 | 640 | 191 | 1,338 | 880 | 242 | 1,761 | 1,160 | 300 | 2,242 | 1,475 | 390 | 2,774 | 1,835 | 469 | 3,370 | 2,215 | 555 | 4,023 | 2,660 | |
6 | 128 | 661 | 435 | 171 | 967 | 630 | 219 | 1,330 | 870 | 276 | 1,753 | 1,150 | 341 | 2,235 | 1,470 | 437 | 2,767 | 1,820 | 523 | 3,363 | 2,210 | 618 | 4,017 | 2,650 | |
8 | 0 | 0 | 1,261 | 660 | 0 | 1,858 | 970 | 0 | 2,571 | 1,320 | 0 | 3,399 | 1,740 | 0 | 4,333 | 2,220 | 0 | 5,387 | 2,750 | 0 | 6,555 | 3,360 | 0 | 7,838 | 4,010 |
2 | 71 | 770 | 515 | 98 | 1,124 | 745 | 130 | 1,543 | 1,020 | 168 | 2,030 | 1,340 | 212 | 2,584 | 1,700 | 278 | 3,196 | 2,110 | 336 | 3,882 | 2,560 | 401 | 4,634 | 3,050 | |
5 | 115 | 758 | 503 | 154 | 1,110 | 733 | 199 | 1,528 | 1,010 | 251 | 2,013 | 1,330 | 311 | 2,563 | 1,685 | 398 | 3,180 | 2,090 | 476 | 3,863 | 2,545 | 562 | 4,612 | 3,040 | |
8 | 137 | 746 | 490 | 180 | 1,097 | 720 | 231 | 1,514 | 1,000 | 289 | 2,000 | 1,320 | 354 | 2,552 | 1,670 | 450 | 3,163 | 2,070 | 537 | 3,850 | 2,530 | 630 | 4,602 | 3,030 | |
10 | 0 | 0 | 1,377 | 720 | 0 | 2,036 | 1,060 | 0 | 2,825 | 1,450 | 0 | 3,742 | 1,925 | 0 | 4,782 | 2,450 | 0 | 5,955 | 3,050 | 0 | 7,254 | 3,710 | 0 | 8,682 | 4,450 |
2 | 68 | 852 | 560 | 93 | 1,244 | 850 | 124 | 1,713 | 1,130 | 161 | 2,256 | 1,480 | 202 | 2,868 | 1,890 | 264 | 3,556 | 2,340 | 319 | 4,322 | 2,840 | 378 | 5,153 | 3,390 | |
5 | 112 | 839 | 547 | 149 | 1,229 | 829 | 192 | 1,696 | 1,105 | 243 | 2,238 | 1,461 | 300 | 2,849 | 1,871 | 382 | 3,536 | 2,318 | 458 | 4,301 | 2,818 | 540 | 5,132 | 3,371 | |
10 | 142 | 817 | 525 | 187 | 1,204 | 795 | 238 | 1,669 | 1,080 | 298 | 2,209 | 1,430 | 364 | 2,818 | 1,840 | 459 | 3,504 | 2,280 | 546 | 4,268 | 2,780 | 641 | 5,099 | 3,340 | |
15 | 0 | 0 | 1,596 | 840 | 0 | 2,380 | 1,240 | 0 | 3,323 | 1,720 | 0 | 4,423 | 2,270 | 0 | 5,678 | 2,900 | 0 | 7,099 | 3,620 | 0 | 8,665 | 4,410 | 0 | 10,393 | 5,300 |
2 | 63 | 1,019 | 675 | 86 | 1,495 | 985 | 114 | 2,062 | 1,350 | 147 | 2,719 | 1,770 | 186 | 3,467 | 2,260 | 239 | 4,304 | 2,800 | 290 | 5,232 | 3,410 | 346 | 6,251 | 4,080 | |
5 | 105 | 1,003 | 660 | 140 | 1,476 | 967 | 182 | 2,041 | 1,327 | 229 | 2,696 | 1,748 | 283 | 3,442 | 2,235 | 355 | 4,278 | 2,777 | 426 | 5,204 | 3,385 | 501 | 6,222 | 4,057 | |
10 | 135 | 977 | 635 | 177 | 1,446 | 936 | 227 | 2,009 | 1,289 | 283 | 2,659 | 1,712 | 346 | 3,402 | 2,193 | 432 | 4,234 | 2,739 | 510 | 5,159 | 3,343 | 599 | 6,175 | 4,019 | |
15 | 155 | 953 | 610 | 202 | 1,418 | 905 | 257 | 1,976 | 1,250 | 318 | 2,623 | 1,675 | 385 | 3,363 | 2,150 | 479 | 4,192 | 2,700 | 564 | 5,115 | 3,300 | 665 | 6,129 | 3,980 | |
20 | 0 | 0 | 1,756 | 930 | 0 | 2,637 | 1,350 | 0 | 3,701 | 1,900 | 0 | 4,948 | 2,520 | 0 | 6,376 | 3,250 | 0 | 7,988 | 4,060 | 0 | 9,785 | 4,980 | 0 | 11,753 | 6,000 |
2 | 59 | 1,150 | 755 | 81 | 1,694 | 1,100 | 107 | 2,343 | 1,520 | 139 | 3,097 | 2,000 | 175 | 3,955 | 2,570 | 220 | 4,916 | 3,200 | 269 | 5,983 | 3,910 | 321 | 7,154 | 4,700 | |
5 | 101 | 1,133 | 738 | 135 | 1,674 | 1,079 | 174 | 2,320 | 1,498 | 219 | 3,071 | 1,978 | 270 | 3,926 | 2,544 | 337 | 4,885 | 3,174 | 403 | 5,950 | 3,880 | 475 | 7,119 | 4,662 | |
10 | 130 | 1,105 | 710 | 172 | 1,641 | 1,045 | 220 | 2,282 | 1,460 | 273 | 3,029 | 1,940 | 334 | 3,880 | 2,500 | 413 | 4,835 | 3,130 | 489 | 5,896 | 3,830 | 573 | 7,063 | 4,600 | |
15 | 150 | 1,078 | 688 | 195 | 1,609 | 1,018 | 248 | 2,245 | 1,425 | 306 | 2,988 | 1,910 | 372 | 3,835 | 2,465 | 459 | 4,786 | 3,090 | 541 | 5,844 | 3,795 | 631 | 7,007 | 4,575 | |
20 | 167 | 1,052 | 665 | 217 | 1,578 | 990 | 273 | 2,210 | 1,390 | 335 | 2,948 | 1,880 | 404 | 3,791 | 2,430 | 495 | 4,737 | 3,050 | 585 | 5,792 | 3,760 | 689 | 6,953 | 4,550 |
(continued)
TABLE 504.2(1)‒continued 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 | |||||||||||||||||||||||
10 | 12 | 14 | 16 | 18 | 20 | 22 | 24 | ||||||||||||||||||
APPLIANCE INPUT RATING 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 | ||
30 | 0 | 0 | 1,977 | 1,060 | 0 | 3,004 | 1,550 | 0 | 4,252 | 2,170 | 0 | 5,725 | 2,920 | 0 | 7,420 | 3,770 | 0 | 9,341 | 4,750 | 0 | 11,483 | 5,850 | 0 | 13,848 | 7,060 |
2 | 54 | 1,351 | 865 | 74 | 2,004 | 1,310 | 98 | 2,786 | 1,800 | 127 | 3,696 | 2,380 | 159 | 4,734 | 3,050 | 199 | 5,900 | 3,810 | 241 | 7,194 | 4,650 | 285 | 8,617 | 5,600 | |
5 | 96 | 1,332 | 851 | 127 | 1,981 | 1,289 | 164 | 2,759 | 1,775 | 206 | 3,666 | 2,350 | 252 | 4,701 | 3,020 | 312 | 5,863 | 3,783 | 373 | 7,155 | 4,622 | 439 | 8,574 | 5,552 | |
10 | 125 | 1,301 | 829 | 164 | 1,944 | 1,254 | 209 | 2,716 | 1,733 | 259 | 3,617 | 2,300 | 316 | 4,647 | 2,970 | 386 | 5,803 | 3,739 | 456 | 7,090 | 4,574 | 535 | 8,505 | 5,471 | |
15 | 143 | 1,272 | 807 | 187 | 1,908 | 1,220 | 237 | 2,674 | 1,692 | 292 | 3,570 | 2,250 | 354 | 4,594 | 2,920 | 431 | 5,744 | 3,695 | 507 | 7,026 | 4,527 | 590 | 8,437 | 5,391 | |
20 | 160 | 1,243 | 784 | 207 | 1,873 | 1,185 | 260 | 2,633 | 1,650 | 319 | 3,523 | 2,200 | 384 | 4,542 | 2,870 | 467 | 5,686 | 3,650 | 548 | 6,964 | 4,480 | 639 | 8,370 | 5,310 | |
30 | 195 | 1,189 | 745 | 246 | 1,807 | 1,130 | 305 | 2,555 | 1,585 | 369 | 3,433 | 2,130 | 440 | 4,442 | 2,785 | 540 | 5,574 | 3,565 | 635 | 6,842 | 4,375 | 739 | 8,239 | 5,225 | |
50 | 0 | 0 | 2,231 | 1,195 | 0 | 3,441 | 1,825 | 0 | 4,934 | 2,550 | 0 | 6,711 | 3,440 | 0 | 8,774 | 4,460 | 0 | 11,129 | 5,635 | 0 | 13,767 | 6,940 | 0 | 16,694 | 8,430 |
2 | 41 | 1,620 | 1,010 | 66 | 2,431 | 1,513 | 86 | 3,409 | 2,125 | 113 | 4,554 | 2,840 | 141 | 5,864 | 3,670 | 171 | 7,339 | 4,630 | 209 | 8,980 | 5,695 | 251 | 10,788 | 6,860 | |
5 | 90 | 1,600 | 996 | 118 | 2,406 | 1,495 | 151 | 3,380 | 2,102 | 191 | 4,520 | 2,813 | 234 | 5,826 | 3,639 | 283 | 7,295 | 4,597 | 336 | 8,933 | 5,654 | 394 | 10,737 | 6,818 | |
10 | 118 | 1,567 | 972 | 154 | 2,366 | 1,466 | 196 | 3,332 | 2,064 | 243 | 4,464 | 2,767 | 295 | 5,763 | 3,585 | 355 | 7,224 | 4,542 | 419 | 8,855 | 5,585 | 491 | 10,652 | 6,749 | |
15 | 136 | 1,536 | 948 | 177 | 2,327 | 1,437 | 222 | 3,285 | 2,026 | 274 | 4,409 | 2,721 | 330 | 5,701 | 3,534 | 396 | 7,155 | 4,511 | 465 | 8,779 | 5,546 | 542 | 10,570 | 6,710 | |
20 | 151 | 1,505 | 924 | 195 | 2,288 | 1,408 | 244 | 3,239 | 1,987 | 300 | 4,356 | 2,675 | 361 | 5,641 | 3,481 | 433 | 7,086 | 4,479 | 506 | 8,704 | 5,506 | 586 | 10,488 | 6,670 | |
30 | 183 | 1,446 | 876 | 232 | 2,214 | 1,349 | 287 | 3,150 | 1,910 | 347 | 4,253 | 2,631 | 412 | 5,523 | 3,431 | 494 | 6,953 | 4,421 | 577 | 8,557 | 5,444 | 672 | 10,328 | 6,603 | |
100 | 0 | 0 | 2,491 | 1,310 | 0 | 3,925 | 2,050 | 0 | 5,729 | 2,950 | 0 | 7,914 | 4,050 | 0 | 10,485 | 5,300 | 0 | 13,454 | 6,700 | 0 | 16,817 | 8,600 | 0 | 20,578 | 10,300 |
2 | 30 | 1,975 | 1,170 | 44 | 3,027 | 1,820 | 72 | 4,313 | 2,550 | 95 | 5,834 | 3,500 | 120 | 7,591 | 4,600 | 138 | 9,577 | 5,800 | 169 | 11,803 | 7,200 | 204 | 14,264 | 8,800 | |
5 | 82 | 1,955 | 1,159 | 107 | 3,002 | 1,803 | 136 | 4,282 | 2,531 | 172 | 5,797 | 3,475 | 208 | 7,548 | 4,566 | 245 | 9,528 | 5,769 | 293 | 11,748 | 7,162 | 341 | 14,204 | 8,756 | |
10 | 108 | 1,923 | 1,142 | 142 | 2,961 | 1,775 | 180 | 4,231 | 2,500 | 223 | 5,737 | 3,434 | 268 | 7,478 | 4,509 | 318 | 9,447 | 5,717 | 374 | 11,658 | 7,100 | 436 | 14,105 | 8,683 | |
15 | 126 | 1,892 | 1,124 | 163 | 2,920 | 1,747 | 206 | 4,182 | 2,469 | 252 | 5,678 | 3,392 | 304 | 7,409 | 4,451 | 358 | 9,367 | 5,665 | 418 | 11,569 | 7,037 | 487 | 14,007 | 8,610 | |
20 | 141 | 1,861 | 1,107 | 181 | 2,880 | 1,719 | 226 | 4,133 | 2,438 | 277 | 5,619 | 3,351 | 330 | 7,341 | 4,394 | 387 | 9,289 | 5,613 | 452 | 11,482 | 6,975 | 523 | 13,910 | 8,537 | |
30 | 170 | 1,802 | 1,071 | 215 | 2,803 | 1,663 | 265 | 4,037 | 2,375 | 319 | 5,505 | 3,267 | 378 | 7,209 | 4,279 | 446 | 9,136 | 5,509 | 514 | 11,310 | 6,850 | 592 | 13,720 | 8,391 | |
50 | 241 | 1,688 | 1,000 | 292 | 2,657 | 1,550 | 350 | 3,856 | 2,250 | 415 | 5,289 | 3,100 | 486 | 6,956 | 4,050 | 572 | 8,841 | 5,300 | 659 | 10,979 | 6,600 | 752 | 13,354 | 8,100 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
TABLE 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 | |||||||||||
Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | Mln | 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 |
(continued)
TABLE 504.2(2)-continued TYPE B DOUBLE-WALL GAS VENT
Number of Appliances | Single |
Appliance Type | Category I |
Appliance Vent Connection | Single-wall metal connector |
HEGHT (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 | |||||||||||
Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | Mln | Max | Max | ||
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 | |
100 | 0 | NA | NA | NA | 49 | 214 | NA | 69 | 403 | NA | 100 | 659 | 395 | 131 | 991 | 555 | 166 | 1,404 | 765 | 207 | 1,900 | 1,033 | 273 | 2,479 | 1,300 | 395 | 3,912 | 2,042 |
2 | NA | NA | NA | 51 | 192 | NA | 70 | 351 | NA | 98 | 563 | 373 | 125 | 828 | 508 | 158 | 1,152 | 698 | 196 | 1,532 | 933 | 259 | 1,970 | 1,168 | 371 | 3,021 | 1,817 | |
5 | NA | NA | NA | 67 | 186 | NA | 90 | 342 | NA | 125 | 551 | 366 | 156 | 813 | 501 | 194 | 1,134 | 688 | 240 | 1,511 | 921 | 322 | 1,945 | 1,153 | 460 | 2,990 | 1,796 | |
10 | NA | NA | NA | 85 | 175 | NA | 113 | 324 | NA | 153 | 532 | 354 | 191 | 789 | 486 | 238 | 1,104 | 672 | 293 | 1,477 | 902 | 389 | 1.905 | 1,133 | 547 | 2,938 | 1,763 | |
15 | NA | NA | NA | 132 | 162 | NA | 138 | 310 | NA | 188 | 511 | 343 | 230 | 764 | 473 | 281 | 1,075 | 656 | 342 | 1,443 | 884 | 447 | 1,865 | 1,110 | 618 | 2,888 | 1,730 | |
20 | NA | NA | NA | NA | NA | NA | 168 | 295 | NA | 224 | 487 | NA | 270 | 739 | 458 | 325 | 1,046 | 639 | 391 | 1,410 | 864 | 507 | 1,825 | 1,087 | 690 | 2,838 | 1,696 | |
30 | NA | NA | NA | NA | NA | NA | 231 | 264 | NA | 301 | 448 | NA | 355 | 685 | NA | 418 | 988 | NA | 491 | 1,343 | 824 | 631 | 1,747 | 1,041 | 834 | 2,739 | 1,627 | |
50 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 540 | 584 | NA | 617 | 866 | NA | 711 | 1,205 | NA | 895 | 1,591 | NA | 1,138 | 2,547 | 1,489 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
TABLE 504.2(3) MASONRY CHIMNEY
Number of Appliances | Single |
Appliance Type | Category I |
Appliance Vent Connection | Type B double-wall connector |
HEIGHT (H) (feet) | LATERAL (L) (feet) | TYPE B DOUBLE-WALL CONNECTOR DIAMETER‒(D) Inches to be used with chimney areas within the size limits at bottom | ||||||||||||||||||||||||||
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 | 2 | NA | NA | 28 | NA | NA | 52 | NA | NA | 86 | NA | NA | 130 | NA | NA | 180 | NA | NA | 247 | NA | NA | 320 | NA | NA | 401 | NA | NA | 581 |
5 | NA | NA | 25 | NA | NA | 49 | NA | NA | 82 | NA | NA | 117 | NA | NA | 165 | NA | NA | 231 | NA | NA | 298 | NA | NA | 376 | NA | NA | 561 | |
8 | 2 | NA | NA | 29 | NA | NA | 55 | NA | NA | 93 | NA | NA | 145 | NA | NA | 198 | NA | NA | 266 | 84 | 590 | 350 | 100 | 728 | 446 | 139 | 1,024 | 651 |
5 | NA | NA | 26 | NA | NA | 52 | NA | NA | 88 | NA | NA | 134 | NA | NA | 183 | NA | NA | 247 | NA | NA | 328 | 149 | 711 | 423 | 201 | 1,007 | 640 | |
8 | NA | NA | 24 | NA | NA | 48 | NA | NA | 83 | NA | NA | 127 | NA | NA | 175 | NA | NA | 239 | NA | NA | 318 | 173 | 695 | 410 | 231 | 990 | 623 | |
10 | 2 | NA | NA | 31 | NA | NA | 61 | NA | NA | 103 | NA | NA | 162 | NA | NA | 221 | 68 | 519 | 298 | 82 | 655 | 388 | 98 | 810 | 491 | 136 | 1,144 | 724 |
5 | NA | NA | 28 | NA | NA | 57 | NA | NA | 96 | NA | NA | 148 | NA | NA | 204 | NA | NA | 277 | 124 | 638 | 365 | 146 | 791 | 466 | 196 | 1,124 | 712 | |
10 | NA | NA | 25 | NA | NA | 50 | NA | NA | 87 | NA | NA | 139 | NA | NA | 191 | NA | NA | 263 | 155 | 610 | 347 | 182 | 762 | 444 | 240 | 1,093 | 668 | |
15 | 2 | NA | NA | 35 | NA | NA | 67 | NA | NA | 114 | NA | NA | 179 | 53 | 475 | 250 | 64 | 613 | 336 | 77 | 779 | 441 | 92 | 968 | 562 | 127 | 1,376 | 841 |
5 | NA | NA | 35 | NA | NA | 62 | NA | NA | 107 | NA | NA | 164 | NA | NA | 231 | 99 | 594 | 313 | 118 | 759 | 416 | 139 | 946 | 533 | 186 | 1,352 | 828 | |
10 | NA | NA | 28 | NA | NA | 55 | NA | NA | 97 | NA | NA | 153 | NA | NA | 216 | 126 | 565 | 296 | 148 | 727 | 394 | 173 | 912 | 567 | 229 | 1,315 | 777 | |
15 | NA | NA | NA | NA | NA | 48 | NA | NA | 89 | NA | NA | 141 | NA | NA | 201 | NA | NA | 281 | 171 | 698 | 375 | 198 | 880 | 485 | 259 | 1,280 | 742 | |
20 | 2 | NA | NA | 38 | NA | NA | 74 | NA | NA | 124 | NA | NA | 201 | 51 | 522 | 274 | 61 | 678 | 375 | 73 | 867 | 491 | 87 | 1,083 | 627 | 121 | 1,548 | 953 |
5 | NA | NA | 36 | NA | NA | 68 | NA | NA | 116 | NA | NA | 184 | 80 | 503 | 254 | 95 | 658 | 350 | 113 | 845 | 463 | 133 | 1,059 | 597 | 179 | 1,523 | 933 | |
10 | NA | NA | NA | NA | NA | 60 | NA | NA | 107 | NA | NA | 172 | NA | NA | 237 | 122 | 627 | 332 | 143 | 811 | 440 | 167 | 1,022 | 566 | 221 | 1,482 | 879 | |
15 | NA | NA | NA | NA | NA | NA | NA | NA | 97 | NA | NA | 159 | NA | NA | 220 | NA | NA | 314 | 165 | 780 | 418 | 191 | 987 | 541 | 251 | 1,443 | 840 | |
20 | NA | NA | NA | NA | NA | NA | NA | NA | 83 | NA | NA | 148 | NA | NA | 206 | NA | NA | 296 | 186 | 750 | 397 | 214 | 955 | 513 | 277 | 1,406 | 807 |
(continued)
TABLE 504.2(3)‒continued MASONRY CHIMNEY
Number of Appliances | Single3 |
Appliance Type | Category I |
Appliance Vent Connection | Type B double-wall connector |
HEIGHT (H) (feet) | LATERAL (L) (feet) | TYPE B DOUBLE-WALL CONNECTOR DIAMETER ‒(D) Inches to be used with chimney areas within the size limits at bottom | ||||||||||||||||||||||||||
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 | ||
30 | 2 | NA | NA | 41 | NA | NA | 82 | NA | NA | 137 | NA | NA | 216 | 47 | 581 | 303 | 57 | 762 | 421 | 68 | 985 | 558 | 81 | 1,240 | 717 | 111 | 1,793 | 1,112 |
5 | NA | NA | NA | NA | NA | 76 | NA | NA | 128 | NA | NA | 198 | 75 | 561 | 281 | 90 | 741 | 393 | 106 | 962 | 526 | 125 | 1,216 | 683 | 169 | 1,766 | 1,094 | |
10 | NA | NA | NA | NA | NA | 67 | NA | NA | 115 | NA | NA | 184 | NA | NA | 263 | 115 | 709 | 373 | 135 | 927 | 500 | 158 | 1,176 | 648 | 210 | 1,721 | 1,025 | |
15 | NA | NA | NA | NA | NA | NA | NA | NA | 107 | NA | NA | 171 | NA | NA | 243 | NA | NA | 353 | 156 | 893 | 476 | 181 | 1,139 | 621 | 239 | 1,679 | 981 | |
20 | NA | NA | NA | NA | NA | NA | NA | NA | 91 | NA | NA | 159 | NA | NA | 227 | NA | NA | 332 | 176 | 860 | 450 | 203 | 1,103 | 592 | 264 | 1,638 | 940 | |
30 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 188 | NA | NA | 288 | NA | NA | 416 | 249 | 1,035 | 555 | 318 | 1,560 | 877 | |
50 | 2 | NA | NA | NA | NA | NA | 92 | NA | NA | 161 | NA | NA | 251 | NA | NA | 351 | 51 | 840 | 477 | 61 | 1,106 | 633 | 72 | 1,413 | 812 | 99 | 2,080 | 1,243 |
5 | NA | NA | NA | NA | NA | NA | NA | NA | 151 | NA | NA | 230 | NA | NA | 323 | 83 | 819 | 445 | 98 | 1,083 | 596 | 116 | 1,387 | 774 | 155 | 2,052 | 1,225 | |
10 | NA | NA | NA | NA | NA | NA | NA | NA | 138 | NA | NA | 215 | NA | NA | 304 | NA | NA | 424 | 126 | 1,047 | 567 | 147 | 1,347 | 733 | 195 | 2,006 | 1,147 | |
15 | NA | NA | NA | NA | NA | NA | NA | NA | 127 | NA | NA | 199 | NA | NA | 282 | NA | NA | 400 | 146 | 1,010 | 539 | 170 | 1,307 | 702 | 222 | 1,961 | 1,099 | |
20 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 185 | NA | NA | 264 | NA | NA | 376 | 165 | 977 | 511 | 190 | 1,269 | 669 | 246 | 1,916 | 1,050 | |
30 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 327 | NA | NA | 468 | 233 | 1,196 | 623 | 295 | 1,832 | 984 | |
Minimum Internal Area of Chimney (square inches) | 12 | 19 | 28 | 38 | 50 | 63 | 78 | 95 | 132 | |||||||||||||||||||
Maximum Internal Area of Chimney (square inches) | Seven times the listed appliance categorized vent area, flue collar area or draft hood outlet area. |
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 504.2(4) MASONRY CHIMNEY
Number of Appliances | Single |
Appliance Type | Category I |
Appliance Vent Connection | Single-wall metal connector |
HEIGHT (H) (feet) | LATERAL (L) (feet) | SINGLE-WALL METAL CONNECTOR DIAMETER‒(D) Inches to be used with chimney areas within the size limits at bottom | ||||||||||||||||||||||||||
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 | 2 | NA | NA | 28 | NA | NA | 52 | NA | NA | 86 | NA | NA | 130 | NA | NA | 180 | NA | NA | 247 | NA | NA | 319 | NA | NA | 400 | NA | NA | 580 |
5 | NA | NA | 25 | NA | NA | 48 | NA | NA | 81 | NA | NA | 116 | NA | NA | 164 | NA | NA | 230 | NA | NA | 297 | NA | NA | 375 | NA | NA | 560 | |
8 | 2 | NA | NA | 29 | NA | NA | 55 | NA | NA | 93 | NA | NA | 145 | NA | NA | 197 | NA | NA | 265 | NA | NA | 349 | 382 | 725 | 445 | 549 | 1,021 | 650 |
5 | NA | NA | 26 | NA | NA | 51 | NA | NA | 87 | NA | NA | 133 | NA | NA | 182 | NA | NA | 246 | NA | NA | 327 | NA | NA | 422 | 673 | 1,003 | 638 | |
8 | NA | NA | 23 | NA | NA | 47 | NA | NA | 82 | NA | NA | 126 | NA | NA | 174 | NA | NA | 237 | NA | NA | 317 | NA | NA | 408 | 747 | 985 | 621 | |
10 | 2 | NA | NA | 31 | NA | NA | 61 | NA | NA | 102 | NA | NA | 161 | NA | NA | 220 | 216 | 518 | 297 | 271 | 654 | 387 | 373 | 808 | 490 | 536 | 1,142 | 722 |
5 | NA | NA | 28 | NA | NA | 56 | NA | NA | 95 | NA | NA | 147 | NA | NA | 203 | NA | NA | 276 | 334 | 635 | 364 | 459 | 789 | 465 | 657 | 1,121 | 710 | |
10 | NA | NA | 24 | NA | NA | 49 | NA | NA | 86 | NA | NA | 137 | NA | NA | 189 | NA | NA | 261 | NA | NA | 345 | 547 | 758 | 441 | 771 | 1,088 | 665 | |
15 | 2 | NA | NA | 35 | NA | NA | 67 | NA | NA | 113 | NA | NA | 178 | 166 | 473 | 249 | 211 | 611 | 335 | 264 | 776 | 440 | 362 | 965 | 560 | 520 | 1,373 | 840 |
5 | NA | NA | 32 | NA | NA | 61 | NA | NA | 106 | NA | NA | 163 | NA | NA | 230 | 261 | 591 | 312 | 325 | 775 | 414 | 444 | 942 | 531 | 637 | 1,348 | 825 | |
10 | NA | NA | 27 | NA | NA | 54 | NA | NA | 96 | NA | NA | 151 | NA | NA | 214 | NA | NA | 294 | 392 | 722 | 392 | 531 | 907 | 504 | 749 | 1,309 | 774 | |
15 | NA | NA | NA | NA | NA | 46 | NA | NA | 87 | NA | NA | 138 | NA | NA | 198 | NA | NA | 278 | 452 | 692 | 372 | 606 | 873 | 481 | 841 | 1,272 | 738 | |
20 | 2 | NA | NA | 38 | NA | NA | 73 | NA | NA | 123 | NA | NA | 200 | 163 | 520 | 273 | 206 | 675 | 374 | 258 | 864 | 490 | 252 | 1,079 | 625 | 508 | 1,544 | 950 |
5 | NA | NA | 35 | NA | NA | 67 | NA | NA | 115 | NA | NA | 183 | 80 | NA | 252 | 255 | 655 | 348 | 317 | 842 | 461 | 433 | 1,055 | 594 | 623 | 1,518 | 930 | |
10 | NA | NA | NA | NA | NA | 59 | NA | NA | 105 | NA | NA | 170 | NA | NA | 235 | 312 | 622 | 330 | 382 | 806 | 437 | 517 | 1,016 | 562 | 733 | 1,475 | 875 | |
15 | NA | NA | NA | NA | NA | NA | NA | NA | 95 | NA | NA | 156 | NA | NA | 217 | NA | NA | 311 | 442 | 773 | 414 | 591 | 979 | 539 | 823 | 1,434 | 835 | |
20 | NA | NA | NA | NA | NA | NA | NA | NA | 80 | NA | NA | 144 | NA | NA | 202 | NA | NA | 292 | NA | NA | 392 | 663 | 944 | 510 | 911 | 1,394 | 800 |
(continued)
TABLE 504.2(4)‒continued MASONRY CHIMNEY
Number of Appliances | Single |
Appliance Type | Category I |
Appliance Vent Connection | Single-wall metal connector |
HEIGHT (H) (feet) | LATERAL (L) (feet) | SINGLE-WALL METAL CONNECTOR DIAMETER‒(D) Inches to be used with chimney areas within the size limits at bottom | ||||||||||||||||||||||||||
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 | ||
30 | 2 | NA | NA | 41 | NA | NA | 81 | NA | NA | 136 | NA | NA | 215 | 158 | 578 | 302 | 200 | 759 | 420 | 249 | 982 | 556 | 340 | 1,237 | 715 | 489 | 1,789 | 1,110 |
5 | NA | NA | NA | NA | NA | 75 | NA | NA | 127 | NA | NA | 196 | NA | NA | 279 | 245 | 737 | 391 | 306 | 958 | 524 | 417 | 1,210 | 680 | 600 | 1,760 | 1,090 | |
10 | NA | NA | NA | NA | NA | 66 | NA | NA | 113 | NA | NA | 182 | NA | NA | 260 | 300 | 703 | 370 | 370 | 920 | 496 | 500 | 1,168 | 644 | 708 | 1,713 | 1,020 | |
15 | NA | NA | NA | NA | NA | NA | NA | NA | 105 | NA | NA | 168 | NA | NA | 240 | NA | NA | 349 | 428 | 884 | 471 | 572 | 1,128 | 615 | 798 | 1,668 | 975 | |
20 | NA | NA | NA | NA | NA | NA | NA | NA | 88 | NA | NA | 155 | NA | NA | 223 | NA | NA | 327 | NA | NA | 445 | 643 | 1,089 | 585 | 883 | 1,624 | 932 | |
30 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 182 | NA | NA | 281 | NA | NA | 408 | NA | NA | 544 | 1,055 | 1,539 | 865 | |
50 | 2 | NA | NA | NA | NA | NA | 91 | NA | NA | 160 | NA | NA | 250 | NA | NA | 350 | 191 | 837 | 475 | 238 | 1,103 | 631 | 323 | 1,408 | 810 | 463 | 2,076 | 1,240 |
5 | NA | NA | NA | NA | NA | NA | NA | NA | 149 | NA | NA | 228 | NA | NA | 321 | NA | NA | 442 | 293 | 1,078 | 593 | 398 | 1,381 | 770 | 571 | 2,044 | 1,220 | |
10 | NA | NA | NA | NA | NA | NA | NA | NA | 136 | NA | NA | 212 | NA | NA | 301 | NA | NA | 420 | 355 | 1,038 | 562 | 447 | 1,337 | 728 | 674 | 1,994 | 1,140 | |
15 | NA | NA | NA | NA | NA | NA | NA | NA | 124 | NA | NA | 195 | NA | NA | 278 | NA | NA | 395 | NA | NA | 533 | 546 | 1,294 | 695 | 761 | 1,945 | 1,090 | |
20 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 180 | NA | NA | 258 | NA | NA | 370 | NA | NA | 504 | 616 | 1,251 | 660 | 844 | 1,898 | 1,040 | |
30 | NA | NA | NA | NA | NA | 48 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 318 | NA | NA | 458 | NA | NA | 610 | 1,009 | 1,805 | 970 | |
Minimum Internal Area of Chimney (square inches) | 12 | 19 | 28 | 38 | 50 | 63 | 78 | 95 | 132 | |||||||||||||||||||
Maximum Internal Area of Chimney (square inches) | Seven times the listed appliance categorized vent area, flue collar area or draft hood outlet area. |
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 504.2(5) SINGLE-WALL METAL PIPE OR TYPE B ASBESTOS CEMENT VENT
Number of Appliances | Single |
Appliance Type | Draft hood equipped |
Appliance Vent Connection | Connected directly to pipe or vent |
HEIGHT (H) (feet) | LATERAL (L) (feet) | VENT DIAMETER‒(D) inches | |||||||
3 | 4 | 5 | 6 | 7 | 8 | 10 | 12 | ||
MAXIMUM APPLIANCE INPUT RATING IN THOUSANDS OF BTU/H | |||||||||
6 | 0 | 39 | 70 | 116 | 170 | 232 | 312 | 500 | 750 |
2 | 31 | 55 | 94 | 141 | 194 | 260 | 415 | 620 | |
5 | 28 | 51 | 88 | 128 | 177 | 242 | 390 | 600 | |
8 | 0 | 42 | 76 | 126 | 185 | 252 | 340 | 542 | 815 |
2 | 32 | 61 | 102 | 154 | 210 | 284 | 451 | 680 | |
5 | 29 | 56 | 95 | 141 | 194 | 264 | 430 | 648 | |
10 | 24 | 49 | 86 | 131 | 180 | 250 | 406 | 625 | |
10 | 0 | 45 | 84 | 138 | 202 | 279 | 372 | 606 | 912 |
2 | 35 | 67 | 111 | 168 | 233 | 311 | 505 | 760 | |
5 | 32 | 61 | 104 | 153 | 215 | 289 | 480 | 724 | |
10 | 27 | 54 | 94 | 143 | 200 | 274 | 455 | 700 | |
15 | NA | 46 | 84 | 130 | 186 | 258 | 432 | 666 | |
15 | 0 | 49 | 91 | 151 | 223 | 312 | 420 | 684 | 1,040 |
2 | 39 | 72 | 122 | 186 | 260 | 350 | 570 | 865 | |
5 | 35 | 67 | 110 | 170 | 240 | 325 | 540 | 825 | |
10 | 30 | 58 | 103 | 158 | 223 | 308 | 514 | 795 | |
15 | NA | 50 | 93 | 144 | 207 | 291 | 488 | 760 | |
20 | NA | NA | 82 | 132 | 195 | 273 | 466 | 726 | |
20 | 0 | 53 | 101 | 163 | 252 | 342 | 470 | 770 | 1,190 |
2 | 42 | 80 | 136 | 210 | 286 | 392 | 641 | 990 | |
5 | 38 | 74 | 123 | 192 | 264 | 364 | 610 | 945 | |
10 | 32 | 65 | 115 | 178 | 246 | 345 | 571 | 910 | |
15 | NA | 55 | 104 | 163 | 228 | 326 | 550 | 870 | |
20 | NA | NA | 91 | 149 | 214 | 306 | 525 | 832 | |
30 | 0 | 56 | 108 | 183 | 276 | 384 | 529 | 878 | 1,370 |
2 | 44 | 84 | 148 | 230 | 320 | 441 | 730 | 1,140 | |
5 | NA | 78 | 137 | 210 | 296 | 410 | 694 | 1,080 | |
10 | NA | 68 | 125 | 196 | 274 | 388 | 656 | 1,050 | |
15 | NA | NA | 113 | 177 | 258 | 366 | 625 | 1,000 | |
20 | NA | NA | 99 | 163 | 240 | 344 | 596 | 960 | |
30 | NA | NA | NA | NA | 192 | 295 | 540 | 890 | |
50 | 0 | NA | 120 | 210 | 310 | 443 | 590 | 980 | 1,550 |
2 | NA | 95 | 171 | 260 | 370 | 492 | 820 | 1,290 | |
5 | NA | NA | 159 | 234 | 342 | 474 | 780 | 1,230 | |
10 | NA | NA | 146 | 221 | 318 | 456 | 730 | 1,190 | |
15 | NA | NA | NA | 200 | 292 | 407 | 705 | 1,130 | |
20 | NA | NA | NA | 185 | 276 | 384 | 670 | 1,080 | |
30 | NA | NA | NA | NA | 222 | 330 | 605 | 1,010 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
TABLE 504.2(6) EXTERIOR MASONRY CHIMNEY
Number of Appliances | Single |
Appliance Type | NAT |
Appliance Vent Connection | Type B double-wall connector |
MINIMUM ALLOWABLE INPUT RATING OF SPACE-HEATING APPLIANCE IN THOUSANDS OF BTU PER HOUR | |||||||||
VENT HEIGHT (feet) | Internal area of chimney (square inches) | ||||||||
12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | ||
37°F or Greater | Local 99% Winter Design Temperature: 37°F or Greater | ||||||||
6 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
10 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
15 | NA | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
20 | NA | NA | 123 | 190 | 249 | 184 | 0 | 0 | |
30 | NA | NA | NA | NA | NA | 393 | 334 | 0 | |
50 | NA | NA | NA | NA | NA | NA | NA | 579 | |
27 to 36°F | Local 99% Winter Design Temperature: 27 to 36°F | ||||||||
6 | 0 | 0 | 68 | 116 | 156 | 180 | 212 | 266 | |
8 | 0 | 0 | 82 | 127 | 167 | 187 | 214 | 263 | |
10 | 0 | 51 | 97 | 141 | 183 | 201 | 225 | 265 | |
15 | NA | NA | NA | NA | 233 | 253 | 274 | 305 | |
20 | NA | NA | NA | NA | NA | 307 | 330 | 362 | |
30 | NA | NA | NA | NA | NA | 419 | 445 | 485 | |
50 | NA | NA | NA | NA | NA | NA | NA | 763 | |
17 to 26°F | Local 99% Winter Design Temperature: 17 to 26°F | ||||||||
6 | NA | NA | NA | NA | NA | 215 | 259 | 349 | |
8 | NA | NA | NA | NA | 197 | 226 | 264 | 352 | |
10 | NA | NA | NA | NA | 214 | 245 | 278 | 358 | |
15 | NA | NA | NA | NA | NA | 296 | 331 | 398 | |
20 | NA | NA | NA | NA | NA | 352 | 387 | 457 | |
30 | NA | NA | NA | NA | NA | NA | 507 | 581 | |
50 | NA | NA | NA | NA | NA | NA | NA | NA | |
5 to 16°F | Local 99% Winter Design Temperature: 5 to 16°F | ||||||||
6 | NA | NA | NA | NA | NA | NA | NA | 416 | |
8 | NA | NA | NA | NA | NA | NA | 312 | 423 | |
10 | NA | NA | NA | NA | NA | 289 | 331 | 430 | |
15 | NA | NA | NA | NA | NA | NA | 393 | 485 | |
20 | NA | NA | NA | NA | NA | NA | 450 | 547 | |
30 | NA | NA | NA | NA | NA | NA | NA | 682 | |
50 | NA | NA | NA | NA | NA | NA | NA | 972 | |
-10 to 4°F | Local 99% Winter Design Temperature:-10 to 4°F | ||||||||
6 | NA | NA | NA | NA | NA | NA | NA | 484 | |
8 | NA | NA | NA | NA | NA | NA | NA | 494 | |
10 | NA | NA | NA | NA | NA | NA | NA | 513 | |
15 | NA | NA | NA | NA | NA | NA | NA | 586 | |
20 | NA | NA | NA | NA | NA | NA | NA | 650 | |
30 | NA | NA | NA | NA | NA | NA | NA | 805 | |
50 | NA | NA | NA | NA | NA | NA | NA | 1003 | |
-11°F or Lower | Local 99% Winter Design Temperature: -11°F or Lower | ||||||||
Not recommended for any vent configurations |
For SI: °C = (°F - 32)/1.8, 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
Note: See Figure B-19 in Appendix B for a map showing local 99-percent winter design temperatures in the United States.
These venting tables shall not be used where obstructions, as described in Section 503.15, 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:
1. The maximum capacity of the vent system shall be determined using the "NAT Max"column.
2. 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.
1. The maximum capacity of the vent system shall be determined using the "NAT Max"column.
2. 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:
1. The total vent height (H) is not less than 10 feet (3048 mm).
2. 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.
3. 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.
4. The maximum capacity listed in the tables for a fanassisted appliance is reduced by 10 percent (0.90 × maximum table capacity).
5. 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 fanassisted appliances.
1. The total vent height (H) is not less than 10 feet (3048 mm).
2. 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.
3. 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.
4. The maximum capacity listed in the tables for a fanassisted appliance is reduced by 10 percent (0.90 × maximum table capacity).
5. 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 fanassisted appliances.
Single-appliance venting configurations with zero (0) lateral lengths in Tables 504.2(1),504.2(2) and 504.2(5) 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 504.2(1) through 504.2(5).
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 504.2(1) or 504.2(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 504.2(1) or 504.2(2). Corrugated metallic liner systems installed with bends or offsets shall have their maximum capacity further reduced in accordance with Section 504.2.3. 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.
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 504.2(1), 504.2(2), 504.2(3), 504.2(4) and 504.2(5) 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 503.6.4, and where vents terminate in accordance with Section 503.6.4, 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 R8.
Table 504.2(3) in combination with Table 504.2(6) shall be used for clay-tile-lined exterior masonry chimneys, provided that all of the following are met:
1. Vent connector is a Type B double wall.
2. Vent connector length is limited to 11/2 feet for each inch (18 mm per mm) of vent connector diameter
3. The appliance is draft hood equipped.
4. The input rating is less than the maximum capacity given by Table 504.2(3).
5. For a water heater, the outdoor design temperature is not less than 5°F (-15°C).
6. For a space-heating appliance, the input rating is greater than the minimum capacity given by Table 504.2(6).
Table 504.2(3) in combination with Table 504.2(6) shall be used for clay-tile-lined exterior masonry chimneys, provided that all of the following are met:
1. Vent connector is a Type B double wall.
2. Vent connector length is limited to 11/2 feet for each inch (18 mm per mm) of vent connector diameter
3. The appliance is draft hood equipped.
4. The input rating is less than the maximum capacity given by Table 504.2(3).
5. For a water heater, the outdoor design temperature is not less than 5°F (-15°C).
6. For a space-heating appliance, the input rating is greater than the minimum capacity given by Table 504.2(6).
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.
For vent heights less than 6 feet (1829 mm) and greater than shown in the tables, engineering methods shall be used to calculate vent capacities.
Where the actual height of a vent falls between entries in the height column of the applicable table in Tables 504.2(1) through 504.2(6), 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 504.3(1) through 504.3(7) shall be subject to the requirements of Sections 504.3.1 through 504.3.28.
TABLE 504.3(1) TYPE B DOUBLE-WALL VENT
(continued)
TABLE 504.3(1)-continued TYPE B DOUBLE-WALL VENT
TABLE 504.3(2) TYPE B DOUBLE-WALL VENT
TABLE 504.3(3) MASONRY CHIMNEY
TABLE 504.3(4) MASONRY CHIMNEY
TABLE 504.3(5) SINGLE-WALL METAL PIPE OR TYPE ASBESTOS CEMENT VENT
TABLE 504.3(6a) EXTERIOR MASONRY CHIMNEY
TABLE 504.3(6b) EXTERIOR MASONRY CHIMNEY
(continued)
TABLE 504.3(6b) EXTERIOR MASONRY CHIMNEY-continued
TABLE 504.3(7a) EXTERIOR MASONRY CHIMNEY
TABLE 504.3(7b) EXTERIOR MASONRY CHIMNEY
TABLE 504.3(7b) EXTERIOR MASONRY CHIMNEY‒continued
TABLE 504.3(1) TYPE B DOUBLE-WALL VENT
Number of Appliances | Two or more |
Appliance Type | Category I |
Appliance 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 | |
50 | 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 | 1,014 | 478 | |
3 | 22 | 75 | 48 | 33 | 141 | 86 | 46 | 229 | 134 | 61 | 366 | 194 | 83 | 502 | 263 | 103 | 661 | 343 | 126 | 842 | 441 | 151 | 1,043 | 538 | |
100 | 1 | 18 | 82 | 37 | 28 | 158 | 66 | 40 | 262 | 104 | 53 | 442 | 150 | 73 | 611 | 204 | 91 | 810 | 266 | 112 | 1,038 | 341 | 135 | 1,285 | 417 |
2 | 19 | 83 | 44 | 30 | 161 | 79 | 42 | 267 | 123 | 55 | 447 | 178 | 75 | 619 | 242 | 94 | 822 | 316 | 115 | 1,054 | 405 | 139 | 1,306 | 494 | |
3 | 20 | 84 | 50 | 31 | 163 | 89 | 44 | 272 | 138 | 57 | 452 | 109 | 78 | 627 | 272 | 97 | 834 | 355 | 118 | 1,069 | 455 | 142 | 1,327 | 555 |
COMMON VENT CAPACITY | |||||||||||||||||||||
VENT HEIGHT (H) (feet) | |||||||||||||||||||||
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 |
100 | 175 | 163 | NA | 311 | 277 | NA | 489 | 421 | NA | 751 | 658 | 479 | 1,025 | 873 | 625 | 1,408 | 1,215 | 800 | 1,784 | 1,502 | 975 |
(continued)
TABLE 504.3(1)-continued TYPE B DOUBLE-WALL VENT
Number of Appliances | Two or more |
Appliance Type | Category I |
Appliance Vent Connection | Type B double-wall connector |
VENT CONNECTOR CAPACITY | ||||||||||||||||||||||
VENT HEIGHT (H) (feet) | CONNECTOR RISE (R) (feet) | TYPE B DOUBLE-WALL VENT AND DIAMETER‒(D) inches | ||||||||||||||||||||
12 | 14 | 16 | 18 | 20 | 22 | 24 | ||||||||||||||||
APPLIANCE INPUT RATING LIMITS 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 | 2 | 174 | 764 | 496 | 223 | 1,046 | 653 | 281 | 1,371 | 853 | 346 | 1,772 | 1,080 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
4 | 180 | 897 | 616 | 230 | 1,231 | 827 | 287 | 1,617 | 1,081 | 352 | 2,069 | 1,370 | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
6 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
8 | 2 | 186 | 822 | 516 | 238 | 1,126 | 696 | 298 | 1,478 | 910 | 365 | 1,920 | 1,150 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
4 | 192 | 952 | 644 | 244 | 1,307 | 884 | 305 | 1,719 | 1,150 | 372 | 2,211 | 1,460 | 471 | 2,737 | 1,800 | 560 | 3,319 | 2,180 | 662 | 3,957 | 2,590 | |
6 | 198 | 1,050 | 772 | 252 | 1,445 | 1,072 | 313 | 1,902 | 1,390 | 380 | 2,434 | 1,770 | 478 | 3,018 | 2,180 | 568 | 3,665 | 2,640 | 669 | 4,373 | 3,130 | |
10 | 2 | 196 | 870 | 536 | 249 | 1,195 | 730 | 311 | 1,570 | 955 | 379 | 2,049 | 1,205 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
4 | 201 | 997 | 664 | 256 | 1,371 | 924 | 318 | 1,804 | 1,205 | 387 | 2,332 | 1,535 | 486 | 2,887 | 1,890 | 581 | 3,502 | 2,280 | 686 | 4,175 | 2,710 | |
6 | 207 | 1,095 | 792 | 263 | 1,509 | 1,118 | 325 | 1,989 | 1,455 | 395 | 2,556 | 1,865 | 494 | 3,169 | 2,290 | 589 | 3,849 | 2,760 | 694 | 4,593 | 3,270 | |
15 | 2 | 214 | 967 | 568 | 272 | 1,334 | 790 | 336 | 1,760 | 1,030 | 408 | 2,317 | 1,305 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
4 | 221 | 1,085 | 712 | 279 | 1,499 | 1,006 | 344 | 1,978 | 1,320 | 416 | 2,579 | 1,665 | 523 | 3,197 | 2,060 | 624 | 3,881 | 2,490 | 734 | 4,631 | 2,960 | |
6 | 228 | 1,181 | 856 | 286 | 1,632 | 1,222 | 351 | 2,157 | 1,610 | 424 | 2,796 | 2,025 | 533 | 3,470 | 2,510 | 634 | 4,216 | 3,030 | 743 | 5,035 | 3,600 | |
20 | 2 | 223 | 1,051 | 596 | 291 | 1,443 | 840 | 357 | 1,911 | 1,095 | 430 | 2,533 | 1,385 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
4 | 230 | 1,162 | 748 | 298 | 1,597 | 1,064 | 365 | 2,116 | 1,395 | 438 | 2,778 | 1,765 | 554 | 3,447 | 2,180 | 661 | 4,190 | 2,630 | 772 | 5,005 | 3,130 | |
6 | 237 | 1,253 | 900 | 307 | 1,726 | 1,288 | 373 | 2,287 | 1,695 | 450 | 2,984 | 2,145 | 567 | 3,708 | 2,650 | 671 | 4,511 | 3,190 | 785 | 5,392 | 3,790 | |
30 | 2 | 216 | 1,217 | 632 | 286 | 1,664 | 910 | 367 | 2,183 | 1,190 | 461 | 2,891 | 1,540 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
4 | 223 | 1,316 | 792 | 294 | 1,802 | 1,160 | 376 | 2,366 | 1,510 | 474 | 3,110 | 1,920 | 619 | 3,840 | 2,365 | 728 | 4,861 | 2,860 | 847 | 5,606 | 3,410 | |
6 | 231 | 1,400 | 952 | 303 | 1,920 | 1,410 | 384 | 2,524 | 1,830 | 485 | 3,299 | 2,340 | 632 | 4,080 | 2,875 | 741 | 4,976 | 3,480 | 860 | 5,961 | 4,150 | |
50 | 2 | 206 | 1,479 | 689 | 273 | 2,023 | 1,007 | 350 | 2,659 | 1,315 | 435 | 3,548 | 1,665 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
4 | 213 | 1,561 | 860 | 281 | 2,139 | 1,291 | 359 | 2,814 | 1,685 | 447 | 3,730 | 2,135 | 580 | 4,601 | 2,633 | 709 | 5,569 | 3,185 | 851 | 6,633 | 3,790 | |
6 | 221 | 1,631 | 1,031 | 290 | 2,242 | 1,575 | 369 | 2,951 | 2,055 | 461 | 3,893 | 2,605 | 594 | 4,808 | 3,208 | 724 | 5,826 | 3,885 | 867 | 6,943 | 4,620 | |
100 | 2 | 192 | 1,923 | 712 | 254 | 2,644 | 1,050 | 326 | 3,490 | 1,370 | 402 | 4,707 | 1,740 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
4 | 200 | 1,984 | 888 | 263 | 2,731 | 1,346 | 336 | 3,606 | 1,760 | 414 | 4,842 | 2,220 | 523 | 5,982 | 2,750 | 639 | 7,254 | 3,330 | 769 | 8,650 | 3,950 | |
6 | 208 | 2,035 | 1,064 | 272 | 2,811 | 1,642 | 346 | 3,714 | 2,150 | 426 | 4,968 | 2,700 | 539 | 6,143 | 3,350 | 654 | 7,453 | 4,070 | 786 | 8,892 | 4,810 |
COMMON VENT CAPACITY | |||||||||||||||||||||
VENT HEIGHT (H) (feet) | TYPE B DOUBLE-WALL COMMON VENT DIAMETER‒(D) inches | ||||||||||||||||||||
12 | 14 | 16 | 18 | 20 | 22 | 24 | |||||||||||||||
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 | 900 | 696 | 588 | 1,284 | 990 | 815 | 1,735 | 1,336 | 1,065 | 2,253 | 1,732 | 1,345 | 2,838 | 2,180 | 1,660 | 3,488 | 2,677 | 1,970 | 4,206 | 3,226 | 2,390 |
8 | 994 | 773 | 652 | 1,423 | 1,103 | 912 | 1,927 | 1,491 | 1,190 | 2,507 | 1,936 | 1,510 | 3,162 | 2,439 | 1,860 | 3,890 | 2,998 | 2,200 | 4,695 | 3,616 | 2,680 |
10 | 1,076 | 841 | 712 | 1,542 | 1,200 | 995 | 2,093 | 1,625 | 1,300 | 2,727 | 2,113 | 1645 | 3,444 | 2,665 | 2,030 | 4,241 | 3,278 | 2,400 | 5,123 | 3,957 | 2,920 |
15 | 1,247 | 986 | 825 | 1,794 | 1,410 | 1,158 | 2,440 | 1,910 | 1,510 | 3,184 | 2,484 | 1,910 | 4,026 | 3,133 | 2,360 | 4,971 | 3,862 | 2,790 | 6,016 | 4,670 | 3,400 |
20 | 1,405 | 1,116 | 916 | 2,006 | 1,588 | 1,290 | 2,722 | 2,147 | 1,690 | 3,561 | 2,798 | 2,140 | 4,548 | 3,552 | 2,640 | 5,573 | 4,352 | 3,120 | 6,749 | 5,261 | 3,800 |
30 | 1,658 | 1,327 | 1,025 | 2,373 | 1,892 | 1,525 | 3,220 | 2,558 | 1,990 | 4,197 | 3,326 | 2,520 | 5,303 | 4,193 | 3,110 | 6,539 | 5,157 | 3,680 | 7,940 | 6,247 | 4,480 |
50 | 2,024 | 1,640 | 1,280 | 2,911 | 2,347 | 1,863 | 3,964 | 3,183 | 2,430 | 5,184 | 4,149 | 3,075 | 6,567 | 5,240 | 3,800 | 8,116 | 6,458 | 4,500 | 9,837 | 7,813 | 5,475 |
100 | 2,569 | 2,131 | 1,670 | 3,732 | 3,076 | 2,450 | 5,125 | 4,202 | 3,200 | 6,749 | 5,509 | 4,050 | 8,597 | 6,986 | 5,000 | 10,681 | 8,648 | 5,920 | 13,004 | 10,499 | 7,200 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
TABLE 504.3(2) TYPE B DOUBLE-WALL VENT
Number of Appliances | Two or more |
Appliance Type | Category I |
Appliance 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 | |
50 | 1 | 46 | 69 | 34 | 75 | 128 | 60 | 109 | 207 | 96 | 162 | 336 | 137 | 217 | 460 | 188 | 284 | 604 | 245 | 364 | 768 | 314 | 507 | 951 | 384 |
2 | 49 | 71 | 40 | 79 | 132 | 72 | 114 | 215 | 113 | 170 | 345 | 164 | 226 | 473 | 223 | 294 | 623 | 293 | 376 | 793 | 375 | 520 | 983 | 458 | |
3 | 52 | 72 | 45 | 83 | 136 | 82 | 119 | 221 | 123 | 178 | 353 | 186 | 235 | 486 | 252 | 304 | 640 | 331 | 387 | 816 | 423 | 535 | 1,013 | 518 | |
100 | 1 | 45 | 79 | 34 | 71 | 150 | 61 | 104 | 249 | 98 | 153 | 424 | 140 | 205 | 585 | 192 | 269 | 774 | 249 | 345 | 993 | 321 | 476 | 1,236 | 393 |
2 | 48 | 80 | 41 | 75 | 153 | 73 | 110 | 255 | 115 | 160 | 428 | 167 | 212 | 593 | 228 | 279 | 788 | 299 | 358 | 1,011 | 383 | 490 | 1,259 | 469 | |
3 | 51 | 81 | 46 | 79 | 157 | 85 | 114 | 260 | 129 | 168 | 433 | 190 | 222 | 603 | 256 | 289 | 801 | 339 | 368 | 1,027 | 431 | 506 | 1,280 | 527 |
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 |
100 | 166 | 153 | NA | 297 | 263 | NA | 469 | 398 | NA | 726 | 633 | 464 | 999 | 846 | 606 | 1,378 | 1,185 | 780 | 1,741 | 1,459 | 948 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
TABLE 504.3(3) MASONRY CHIMNEY
Number of Appliances | Two or more |
Appliance Type | Category I |
Appliance 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 | |
30 | 1 | 24 | 54 | 25 | 37 | 111 | 48 | 52 | 192 | 82 | 69 | 357 | 127 | 96 | 504 | 187 | 119 | 680 | 255 | 145 | 883 | 337 | 175 | 1,115 | 432 |
2 | 25 | 60 | 32 | 38 | 122 | 58 | 54 | 208 | 95 | 72 | 376 | 145 | 99 | 531 | 209 | 122 | 715 | 287 | 149 | 928 | 378 | 179 | 1,171 | 484 | |
3 | 26 | 64 | 36 | 40 | 131 | 66 | 56 | 221 | 107 | 74 | 392 | 163 | 101 | 554 | 233 | 125 | 746 | 317 | 152 | 968 | 418 | 182 | 1,220 | 535 | |
50 | 1 | 23 | 51 | 25 | 36 | 116 | 51 | 51 | 209 | 89 | 67 | 405 | 143 | 92 | 582 | 213 | 115 | 798 | 294 | 140 | 1,049 | 392 | 168 | 1,334 | 506 |
2 | 24 | 59 | 32 | 37 | 127 | 61 | 53 | 225 | 102 | 70 | 421 | 161 | 95 | 604 | 235 | 118 | 827 | 326 | 143 | 1,085 | 433 | 172 | 1,379 | 558 | |
3 | 26 | 64 | 36 | 39 | 135 | 69 | 55 | 237 | 115 | 72 | 435 | 80 | 98 | 624 | 260 | 121 | 854 | 357 | 147 | 1,118 | 474 | 176 | 1,421 | 611 | |
100 | 1 | 23 | 46 | 24 | 35 | 108 | 50 | 49 | 208 | 92 | 65 | 428 | 155 | 88 | 640 | 237 | 109 | 907 | 334 | 134 | 1,222 | 454 | 161 | 1,589 | 596 |
2 | 24 | 53 | 31 | 37 | 120 | 60 | 51 | 224 | 105 | 67 | 444 | 174 | 92 | 660 | 260 | 113 | 933 | 368 | 138 | 1,253 | 497 | 165 | 1,626 | 651 | |
3 | 25 | 59 | 35 | 38 | 130 | 68 | 53 | 237 | 118 | 69 | 458 | 193 | 94 | 679 | 285 | 116 | 956 | 399 | 141 | 1,282 | 540 | 169 | 1,661 | 705 |
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 |
100 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 348 | NA | NA | 499 | NA | NA | 669 | 2,053 | 1,921 | 1,058 |
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 504.3(4) MASONRY CHIMNEY
Number of Appliances | Two or more |
Appliance Type | Category I |
Appliance 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 | 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 | |
30 | 1 | NA | NA | 24 | 86 | 108 | 47 | 126 | 187 | 80 | 193 | 347 | 124 | 259 | 492 | 183 | 338 | 665 | 250 | 430 | 864 | 330 | 600 | 1,089 | 421 |
2 | NA | NA | 31 | 91 | 119 | 57 | 132 | 203 | 93 | 201 | 366 | 142 | 269 | 518 | 205 | 348 | 699 | 282 | 442 | 908 | 372 | 613 | 1,145 | 473 | |
3 | NA | NA | 35 | 95 | 127 | 65 | 138 | 216 | 105 | 209 | 381 | 160 | 277 | 540 | 229 | 358 | 729 | 312 | 452 | 946 | 412 | 626 | 1,193 | 524 | |
50 | 1 | NA | NA | 24 | 85 | 113 | 50 | 124 | 204 | 87 | 188 | 392 | 139 | 252 | 567 | 208 | 328 | 778 | 287 | 417 | 1,022 | 383 | 582 | 1,302 | 492 |
2 | NA | NA | 31 | 89 | 123 | 60 | 130 | 218 | 100 | 196 | 408 | 158 | 262 | 588 | 230 | 339 | 806 | 320 | 429 | 1,058 | 425 | 596 | 1,346 | 545 | |
3 | NA | NA | 35 | 94 | 131 | 68 | 136 | 231 | 112 | 205 | 422 | 176 | 271 | 607 | 255 | 349 | 831 | 351 | 440 | 1,090 | 466 | 610 | 1,386 | 597 | |
100 | 1 | NA | NA | 23 | 84 | 104 | 49 | 122 | 200 | 89 | 182 | 410 | 151 | 243 | 617 | 232 | 315 | 875 | 328 | 402 | 1,181 | 444 | 560 | 1,537 | 580 |
2 | NA | NA | 30 | 88 | 115 | 59 | 127 | 215 | 102 | 190 | 425 | 169 | 253 | 636 | 254 | 326 | 899 | 361 | 415 | 1,210 | 488 | 575 | 1,570 | 634 | |
3 | NA | NA | 34 | 93 | 124 | 67 | 133 | 228 | 115 | 199 | 438 | 188 | 262 | 654 | 279 | 337 | 921 | 392 | 427 | 1,238 | 529 | 589 | 1,604 | 687 |
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 |
100 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 494 | NA | NA | 663 | 2,006 | 1,885 | 1,046 |
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 504.3(5) SINGLE-WALL METAL PIPE OR TYPE ASBESTOS CEMENT VENT
Number of Appliances | Two or more |
Appliance Type | Draft hood-equipped |
Appliance Vent Connection | Direct to pipe or vent |
VENT CONNECTOR CAPACITY | |||||||
TOTAL VENT HEIGHT (H) (feet) | CONNECTOR RISE (R) (feet) | VENT CONNECTOR DIAMETER‒(D) inches | |||||
3 | 4 | 5 | 6 | 7 | 8 | ||
MAXIMUM APPLIANCE INPUT RATING IN THOUSANDS OF BTU/H | |||||||
6-8 | 1 | 21 | 40 | 68 | 102 | 146 | 205 |
2 | 28 | 53 | 86 | 124 | 178 | 235 | |
3 | 34 | 61 | 98 | 147 | 204 | 275 | |
15 | 1 | 23 | 44 | 77 | 117 | 179 | 240 |
2 | 30 | 56 | 92 | 134 | 194 | 265 | |
3 | 35 | 64 | 102 | 155 | 216 | 298 | |
30 and up | 1 | 25 | 49 | 84 | 129 | 190 | 270 |
2 | 31 | 58 | 97 | 145 | 211 | 295 | |
3 | 36 | 68 | 107 | 164 | 232 | 321 |
COMMON VENT CAPACITY | |||||||
TOTAL VENT HEIGHT (H) (feet) | COMMON VENT DIAMETER‒(D) inches | ||||||
4 | 5 | 6 | 7 | 8 | 10 | 12 | |
COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU/H | |||||||
6 | 48 | 78 | 111 | 155 | 205 | 320 | NA |
8 | 55 | 89 | 128 | 175 | 234 | 365 | 505 |
10 | 59 | 95 | 136 | 190 | 250 | 395 | 560 |
15 | 71 | 115 | 168 | 228 | 305 | 480 | 690 |
20 | 80 | 129 | 186 | 260 | 340 | 550 | 790 |
30 | NA | 147 | 215 | 300 | 400 | 650 | 940 |
50 | NA | NA | NA | 360 | 490 | 810 | 1,190 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
TABLE 504.3(6a) EXTERIOR MASONRY CHIMNEY
Number of Appliances | Two or more |
Appliance Type | NAT + NAT |
Appliance Vent Connection | Type B double-wall connector |
Combined Appliance Maximum Input Rating in Thousands of Btu per Hour | ||||||||
VENT HEIGHT (feet) | INTERNAL AREA OF CHIMNEY (square inches) | |||||||
12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |
6 | 25 | 46 | 71 | 103 | 143 | 188 | 246 | NA |
8 | 28 | 53 | 82 | 119 | 163 | 218 | 278 | 408 |
10 | 31 | 56 | 90 | 131 | 177 | 236 | 302 | 454 |
15 | NA | 67 | 106 | 152 | 212 | 283 | 365 | 546 |
20 | NA | NA | NA | NA | NA | 325 | 419 | 648 |
30 | NA | NA | NA | NA | NA | NA | 496 | 749 |
50 | NA | NA | NA | NA | NA | NA | NA | 922 |
100 | NA | NA | NA | NA | NA | NA | NA | NA |
TABLE 504.3(6b) EXTERIOR MASONRY CHIMNEY
Number of Appliances | Two or more |
Appliance Type | NAT + NAT |
Appliance Vent Connection | Type B double-wall connector |
Minimum Allowable Input Rating of Space-heating Appliance in Thousands of Btu per Hour | ||||||||
VENT HEIGHT (feet) | INTERNAL AREA OF CHIMNEY (square inches) | |||||||
12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |
37°F or Greater | Local 99% Winter Design Temperature:37°F or Greater | |||||||
6 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | NA |
8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
10 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
15 | NA | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
20 | NA | NA | NA | NA | NA | 184 | 0 | 0 |
30 | NA | NA | NA | NA | NA | 393 | 334 | 0 |
50 | NA | NA | NA | NA | NA | NA | NA | 579 |
100 | NA | NA | NA | NA | NA | NA | NA | NA |
27 to 36°F | Local 99% Winter Design Temperature: 27 to 36°F | |||||||
6 | 0 | 0 | 68 | NA | NA | 180 | 212 | NA |
8 | 0 | 0 | 82 | NA | NA | 187 | 214 | 263 |
10 | 0 | 51 | NA | NA | NA | 201 | 225 | 265 |
15 | NA | NA | NA | NA | NA | 253 | 274 | 305 |
20 | NA | NA | NA | NA | NA | 307 | 330 | 362 |
30 | NA | NA | NA | NA | NA | NA | 445 | 485 |
50 | NA | NA | NA | NA | NA | NA | NA | 763 |
100 | NA | NA | NA | NA | NA | NA | NA | NA |
(continued)
TABLE 504.3(6b) EXTERIOR MASONRY CHIMNEY-continued
Minimum Allowable Input Rating of Space-heating Appliance in Thousands of Btu per Hour | ||||||||
VENT HEIGHT (feet) | INTERNAL AREA OF CHIMNEY (square inches) | |||||||
12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |
17 to 26°F | Local 99% Winter Design Temperature: 17 to 26°F | |||||||
6 | NA | NA | NA | NA | NA | NA | NA | NA |
8 | NA | NA | NA | NA | NA | NA | 264 | 352 |
10 | NA | NA | NA | NA | NA | NA | 278 | 358 |
15 | NA | NA | NA | NA | NA | NA | 331 | 398 |
20 | NA | NA | NA | NA | NA | NA | 387 | 457 |
30 | NA | NA | NA | NA | NA | NA | NA | 581 |
50 | NA | NA | NA | NA | NA | NA | NA | 862 |
100 | NA | NA | NA | NA | NA | NA | NA | NA |
5 to 16°F | Local 99% Winter Design Temperature: 5 to 16°F | |||||||
6 | NA | NA | NA | NA | NA | NA | NA | NA |
8 | NA | NA | NA | NA | NA | NA | NA | NA |
10 | NA | NA | NA | NA | NA | NA | NA | 430 |
15 | NA | NA | NA | NA | NA | NA | NA | 485 |
20 | NA | NA | NA | NA | NA | NA | NA | 547 |
30 | NA | NA | NA | NA | NA | NA | NA | 682 |
50 | NA | NA | NA | NA | NA | NA | NA | NA |
100 | NA | NA | NA | NA | NA | NA | NA | NA |
4°F or Lower | Local 99% Winter Design Temperature: 4°F or Lower | |||||||
Not recommended for any vent configurations |
For SI: °C = (°F - 32)/1.8, 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.
1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
Note: See Figure B-19 in Appendix B for a map showing local 99-percent
winter design temperatures in the United States.
winter design temperatures in the United States.
TABLE 504.3(7a) EXTERIOR MASONRY CHIMNEY
Number of Appliances | Two or more |
Appliance Type | FAN + NAT |
Appliance Vent Connection | Type B double-wall connector |
Combined Appliance Maximum Input Rating in Thousands of Btu per Hour | ||||||||
VENT HEIGHT (feet) | INTERNAL AREA OF CHIMNEY (square inches) | |||||||
12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |
6 | 74 | 119 | 178 | 257 | 351 | 458 | 582 | 853 |
8 | 80 | 130 | 193 | 279 | 384 | 501 | 636 | 937 |
10 | 84 | 138 | 207 | 299 | 409 | 538 | 686 | 1010 |
15 | NA | 152 | 233 | 334 | 467 | 611 | 781 | 1156 |
20 | NA | NA | 250 | 368 | 508 | 668 | 858 | 1286 |
30 | NA | NA | NA | 404 | 564 | 747 | 969 | 1473 |
50 | NA | NA | NA | NA | NA | 831 | 1089 | 1692 |
100 | NA | NA | NA | NA | NA | NA | NA | 1921 |
TABLE 504.3(7b) EXTERIOR MASONRY CHIMNEY
Number of Appliances | Two or more |
Appliance Type | FAN + NAT |
Appliance Vent Connection | Type B double-wall connector |
Minimum Allowable Input Rating of Space-heating Appliance in Thousands of Btu per Hour | ||||||||
VENT HEIGHT (feet) | INTERNAL AREA OF CHIMNEY (square inches) | |||||||
12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |
37°F orGreater | Local 99% Winter Design Temperature: 37°F or Greater | |||||||
6 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
10 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
15 | NA | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
20 | NA | NA | 123 | 190 | 249 | 184 | 0 | 0 |
30 | NA | NA | NA | 334 | 398 | 393 | 334 | 0 |
50 | NA | NA | NA | NA | NA | 714 | 707 | 579 |
100 | NA | NA | NA | NA | NA | NA | NA | 1600 |
27 to 36°F | Local 99% Winter Design Temperature: 27 to 36°F | |||||||
6 | 0 | 0 | 68 | 116 | 156 | 180 | 212 | 266 |
8 | 0 | 0 | 82 | 127 | 167 | 187 | 214 | 263 |
10 | 0 | 51 | 97 | 141 | 183 | 201 | 225 | 265 |
15 | NA | 111 | 142 | 183 | 233 | 253 | 274 | 305 |
20 | NA | NA | 187 | 230 | 284 | 307 | 330 | 362 |
30 | NA | NA | NA | 330 | 319 | 419 | 445 | 485 |
50 | NA | NA | NA | NA | NA | 672 | 705 | 763 |
100 | NA | NA | NA | NA | NA | NA | NA | 1554 |
TABLE 504.3(7b) EXTERIOR MASONRY CHIMNEY‒continued
Minimum Allowable Input Rating of Space-heating Appliance in Thousands of Btu per Hour | ||||||||
VENT HEIGHT (feet) | INTERNAL AREA OF CHIMNEY (square inches) | |||||||
12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |
17 to 26°F | Local 99% Winter Design Temperature: 17 to 26°F | |||||||
6 | 0 | 55 | 99 | 141 | 182 | 215 | 259 | 349 |
8 | 52 | 74 | 111 | 154 | 197 | 226 | 264 | 352 |
10 | NA | 90 | 125 | 169 | 214 | 245 | 278 | 358 |
15 | NA | NA | 167 | 212 | 263 | 296 | 331 | 398 |
20 | NA | NA | 212 | 258 | 316 | 352 | 387 | 457 |
30 | NA | NA | NA | 362 | 429 | 470 | 507 | 581 |
50 | NA | NA | NA | NA | NA | 723 | 766 | 862 |
100 | NA | NA | NA | NA | NA | NA | NA | 1,669 |
5 to 16°F | Local 99% Winter Design Temperature: 5 to 16°F | |||||||
6 | NA | 78 | 121 | 166 | 214 | 252 | 301 | 416 |
8 | NA | 94 | 135 | 182 | 230 | 269 | 312 | 423 |
10 | NA | 111 | 149 | 198 | 250 | 289 | 331 | 430 |
15 | NA | NA | 193 | 247 | 305 | 346 | 393 | 485 |
20 | NA | NA | NA | 293 | 360 | 408 | 450 | 547 |
30 | NA | NA | NA | 377 | 450 | 531 | 580 | 682 |
50 | NA | NA | NA | NA | NA | 797 | 853 | 972 |
100 | NA | NA | NA | NA | NA | NA | NA | 1,833 |
-10 to 4°F | Local 99% Winter Design Temperature:-10 to 4°F | |||||||
6 | NA | NA | 145 | 196 | 249 | 296 | 349 | 484 |
8 | NA | NA | 159 | 213 | 269 | 320 | 371 | 494 |
10 | NA | NA | 175 | 231 | 292 | 339 | 397 | 513 |
15 | NA | NA | NA | 283 | 351 | 404 | 457 | 586 |
20 | NA | NA | NA | 333 | 408 | 468 | 528 | 650 |
30 | NA | NA | NA | NA | NA | 603 | 667 | 805 |
50 | NA | NA | NA | NA | NA | 603 | 667 | 805 |
100 | NA | NA | NA | NA | NA | NA | 955 | 1,003 |
-11°F or Lower | Local 99% Winter Design Temperature:-11°F or Lower | |||||||
Not recommended for any vent configurations |
For SI: °C = (°F - 32)/1.8, 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.
1 foot = 304.8 mm, 1 British thermal unit per hour = 0.2931 W.
Note: See Figure B-19 in Appendix B for a map showing local 99-percent
winter design temperatures in the United States.
winter design temperatures in the United States.
These venting tables shall not be used where obstructions, as described in Section 503.15, 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:
1. The maximum capacity of the vent connector shall be determined using the NAT Max column.
2. The maximum capacity of the vertical vent or chimney shall be determined using the FAN+NAT column when the second appliance is a fan-assisted appliance, or the NAT+NAT column when the second appliance is equipped with a draft hood.
3. The minimum capacity shall be determined as if the appliance were a fan-assisted appliance.
3.1. The minimum capacity of the vent connector shall be determined using the FAN Min column.
3.2. The FAN+FAN column shall be used where the second appliance isa fan-assisted appliance, and the FAN+NAT column shall be used where the second appliance is equipped with a draft hood, to determine whether the vertical vent or chimney configuration is not permitted (NA). Where the vent configuration is NA, the vent configuration shall not be permitted and an alternative venting configuration shall be utilized.
1. The maximum capacity of the vent connector shall be determined using the NAT Max column.
2. The maximum capacity of the vertical vent or chimney shall be determined using the FAN+NAT column when the second appliance is a fan-assisted appliance, or the NAT+NAT column when the second appliance is equipped with a draft hood.
3. The minimum capacity shall be determined as if the appliance were a fan-assisted appliance.
3.1. The minimum capacity of the vent connector shall be determined using the FAN Min column.
3.2. The FAN+FAN column shall be used where the second appliance isa fan-assisted appliance, and the FAN+NAT column shall be used where the second appliance is equipped with a draft hood, to determine whether the vertical vent or chimney configuration is not permitted (NA). Where the vent configuration is NA, the vent configuration shall not be permitted and an alternative venting configuration shall be utilized.
The vent connector shall be routed to the vent utilizing the shortest possible route. Except as provided in Section 504.3.3, the maximum vent connector horizontal length shall be 11/2 feet for each inch (18 mm per mm) of connector diameter as shown in Table 504.3.2
TABLE 504.3.2 MAXIMUM VENT CONNECTOR LENGTH
TABLE 504.3.2 MAXIMUM VENT CONNECTOR LENGTH
CONNECTOR DIAMETER (inches) | CONNECTOR MAXIMUM HORIZONTAL LENGTH (feet) |
3 | 41/2 |
4 | 6 |
5 | 71/2 |
6 | 9 |
7 | 101/2 |
8 | 12 |
9 | 131/2 |
10 | 15 |
12 | 18 |
14 | 21 |
16 | 24 |
18 | 27 |
20 | 30 |
22 | 33 |
24 | 36 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm.
Connectors with longer horizontal lengths than those listed in Section 504.3.2 are permitted under the following conditions:
1. The maximum capacity (FAN Max or NAT Max) of the vent connector shall be reduced 10 percent for each additional multiple of the length allowed by Section 504.3.2. For example, the maximum length listed in Table 504.3.2 for a 4-inch (102 mm) connector is 6 feet (1829 mm). With a connector length greater than 6 feet (1829 mm) but not exceeding 12 feet (3658 mm), the maximum capacity must be reduced by 10 percent (0.90 × maximum vent connector capacity). With a connector length greater than 12 feet (3658 mm) but not exceeding 18 feet (5486 mm), the maximum capacity must be reduced by 20 percent (0.80 × maximum vent capacity).
2. For a connector serving a fan-assisted appliance, the minimum capacity (FAN Min) of the connector shall be determined by referring to the corresponding single-appliance table. For Type B double-wall connectors, Table 504.2(1) shall be used. For singlewall connectors, Table 504.2(2) shall be used. The height (H) and lateral (L) shall be measured according to the procedures for a single-appliance vent, as if the other appliances were not present.
1. The maximum capacity (FAN Max or NAT Max) of the vent connector shall be reduced 10 percent for each additional multiple of the length allowed by Section 504.3.2. For example, the maximum length listed in Table 504.3.2 for a 4-inch (102 mm) connector is 6 feet (1829 mm). With a connector length greater than 6 feet (1829 mm) but not exceeding 12 feet (3658 mm), the maximum capacity must be reduced by 10 percent (0.90 × maximum vent connector capacity). With a connector length greater than 12 feet (3658 mm) but not exceeding 18 feet (5486 mm), the maximum capacity must be reduced by 20 percent (0.80 × maximum vent capacity).
2. For a connector serving a fan-assisted appliance, the minimum capacity (FAN Min) of the connector shall be determined by referring to the corresponding single-appliance table. For Type B double-wall connectors, Table 504.2(1) shall be used. For singlewall connectors, Table 504.2(2) shall be used. The height (H) and lateral (L) shall be measured according to the procedures for a single-appliance vent, as if the other appliances were not present.
Where the vent connectors are combined prior to entering the vertical portion of the common vent to form a common vent manifold, the size of the common vent manifold and the common vent shall be determined by applying a 10-percent reduction(0.90 × maximum common vent capacity) to the common vent capacity part of the common vent tables. The length of the common vent connector manifold (Lm) shall notexceed 11/2feet for each inch (18 mm per mm) of common vent connector manifold diameter (D)
Where the common vertical vent is offset, the maximum capacity of the common vent shall be reduced in accordance with Section 504.3.6. The horizontal length of the common vent offset (Lo) shall not exceed 11/2 feet for each inch (18 mm per mm) of common vent diameter (D). Where multiple offsets occur in a common vent, the total horizontal length of all offsets combined shall not exceed 11/2 feet for each inch (18 mm per mm) of common vent diameter (D)
For each elbow up to and including 45 degrees (0.79 rad) in the common vent, the maximum common vent capacity listed in the venting tables shall be reduced by 5 percent. For each elbow greater than 45 degrees (0.79 rad) up to and including 90 degrees (1.57 rad), the maximum common vent capacity listed in the venting tables shall be reduced by 10 percent.
The vent connector capacities listed in the common vent sizing tables include allowance for two 90-degree (1.57 rad) elbows. For each additional elbow up to and including 45 degrees (0.79 rad), the maximum vent connector capacity listed in the venting tables shall be reduced by 5 percent. For each elbow greater than 45 degrees (0.79 rad) up to and including 90 degrees (1.57 rad), the maximum vent connector capacity listed in the venting tables shall be reduced by 10 percent.
The cross-sectional area of the common vent shall be equal to or greater than the cross-sectional area of the largest connector.
At the point where tee or wye fittings connect to a common vent, the opening size of the fitting shall be equal to the size of the common vent. Such fittings shall not be prohibited from having reducedsize openings at the point of connection of appliance vent connectors.
Tee and wye fittings connected to a common gas vent shall be considered as part of the common gas vent and shall be constructed of materials consistent with that of the common gas vent.
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.
Connector rise (R) for each appliance connector shall be measured from the draft hood outlet or flue collar to the centerline where the vent gas streams come together.
For multiple appliances all located on one floor, available total height (H) shall be measured from the highest draft hood outlet or flue collar up to the level of the outlet of the common vent.
For multistory installations, available total height (H) for each segment of the system shall be the vertical distance between the highest draft hood outlet or flue collar entering that segment and the centerline of the next higher interconnection tee.
The size of the lowest connector and of the vertical vent leading to the lowest interconnection of a multistory system shall be in accordance with Table 504.2(1) or 504.2(2) for available total height (H) up to the lowest interconnection.
Where used in multistory systems, vertical common vents shall be Type B double wall and shall be installed with a listed vent cap.
Offsets in multistory common vent systems shall be limited to a single offset in each system, and systems with an offset shall comply with all of the following:
1. The offset angle shall not exceed 45 degrees (0.79 rad) from vertical.
2. The horizontal length of the offset shall not exceed 11/2 feet for each inch (18 mm per mm) of common vent diameter of the segment in which the offset is located
3. For the segment of the common vertical vent containing the offset, the common vent capacity listed in the common venting tables shall be reduced by 20 percent (0.80 × maximum common vent capacity).
4. A multistory common vent shall not be reduced in size above the offset.
1. The offset angle shall not exceed 45 degrees (0.79 rad) from vertical.
2. The horizontal length of the offset shall not exceed 11/2 feet for each inch (18 mm per mm) of common vent diameter of the segment in which the offset is located
3. For the segment of the common vertical vent containing the offset, the common vent capacity listed in the common venting tables shall be reduced by 20 percent (0.80 × maximum common vent capacity).
4. A multistory common vent shall not be reduced in size above the offset.
Where two or more appliances are connected to a vertical vent or chimney, the flow area of the largest section of vertical vent or chimney shall not exceed seven times the smallest listed appliance categorized vent areas, flue collar area or draft hood outlet area unless designed in accordance with approved engineering methods.
For appliances with more than one input rate, the minimum vent connector capacity (FAN Min) determined from the tables shall be less than the lowest appliance input rating, and the maximum vent connector capacity (FAN Max or NAT Max) determined from the tables shall be greater than the highest appliance input rating.
Listed, corrugated metallic chimney liner systems in masonry chimneys shall be sized by using Table 504.3(1) or 504.3(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 504.3(1) or 504.3(2). Corrugated metallic liner systems installed with bends or offsets shall have their maximum capacity further reduced in accordance with Sections 504.3.5 and 504.3.6. 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. Where double-wall connectors are required, tee and wye fittings used to connect to the common vent chimney liner shall be listed double-wall fittings. Connections between chimney liners and listed double-wall fittings shall be made with listed adapter fittings designed for such purpose.
Tables 504.3(1), 504.3(2), 504.3(3), 504.3(4) and 504.3(5) 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 503.6.4 and where vents terminate in accordance with Section 503.6.4, 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 R8.
Tables 504.3(6a), 504.3(6b), 504.3(7a) and 504.3(7b) shall be used for clay-tile-lined exterior masonry chimneys, provided that all of the following conditions are met:
1. Vent connectors are Type B double wall.
2. Not less than one appliance is draft hood equipped.
3. The combined appliance input rating is less than the maximum capacity given by Table 504.3(6a) for NAT+NAT or Table 504.3(7a) for FAN+NAT.
4. The input rating of each space-heating appliance is greater than the minimum input rating given by Table 504.3(6b) for NAT+NAT or Table 504.3(7b) for FAN+NAT.
5. The vent connector sizing is in accordance with Table 504.3(3).
Tables 504.3(6a), 504.3(6b), 504.3(7a) and 504.3(7b) shall be used for clay-tile-lined exterior masonry chimneys, provided that all of the following conditions are met:
1. Vent connectors are Type B double wall.
2. Not less than one appliance is draft hood equipped.
3. The combined appliance input rating is less than the maximum capacity given by Table 504.3(6a) for NAT+NAT or Table 504.3(7a) for FAN+NAT.
4. The input rating of each space-heating appliance is greater than the minimum input rating given by Table 504.3(6b) for NAT+NAT or Table 504.3(7b) for FAN+NAT.
5. The vent connector sizing is in accordance with Table 504.3(3).
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. Vent connectors for draft hood-equipped appliances shall not be smaller than the draft hood outlet diameter. Where a vent connector size(s) determined from the tables for a fan-assisted appliance(s) is smaller than the flue collar diameter, the use of the smaller size(s) shall be permitted provided that the installation complies with all of the following conditions:
1. Vent connectors for fan-assisted appliance flue collars 12 inches (305mm) in diameter or smaller are not reduced by more than one table size [e.g., 12 inches to 10 inches (305 mm to 254 mm) is a onesize reduction] and those larger than 12 inches (305 mm) in diameter are not reduced more than two table sizes [e.g., 24 inches to 20 inches (610 mm to 508 mm) is a two-size reduction].
2. The fan-assisted appliance(s) is common vented with a draft-hood-equipped appliance(s).
3. The vent connector has a smooth interior wall.
1. Vent connectors for fan-assisted appliance flue collars 12 inches (305mm) in diameter or smaller are not reduced by more than one table size [e.g., 12 inches to 10 inches (305 mm to 254 mm) is a onesize reduction] and those larger than 12 inches (305 mm) in diameter are not reduced more than two table sizes [e.g., 24 inches to 20 inches (610 mm to 508 mm) is a two-size reduction].
2. The fan-assisted appliance(s) is common vented with a draft-hood-equipped appliance(s).
3. The vent connector has a smooth interior wall.
All combinations of pipe sizes, single-wall and double-wall metal pipe shall be allowed within any connector run(s) or within the common vent, provided that all of the appropriate tables permit all of the desired sizes and types of pipe, as if they were used for the entire length of the subject connector or vent. Where single-wall and Type B double-wall metal pipes are used for vent connectors within the same venting system, the common vent must be sized using Table 504.3(2) or 504.3(4), as appropriate.
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.
Where a table permits more than one diameter of pipe to be used for a connector or vent, all the permitted sizes shall be permitted to be used.
Interpolation shall be permitted in calculating capacities for vent dimensions that fall between table entries.
Extrapolation beyond the table entries shall not be permitted.
For vent heights less than 6 feet (1829 mm) and greater than shown in the tables, engineering methods shall be used to calculate vent capacities.
Where the actual height of a vent falls between entries in the height column of the applicable table in Tables 504.3(1) through 504.3(7b), either interpolation shall be used or the lower appliance input rating shown in the table 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.