Sizing Guide

17
Venting Guidelines for Category I Gas Appliances
NAT NAT NA T NAT NAT NA T 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 1046 653 281 1371 853 346 1772 1080 NA NA NA NA NA NA NA NA NA
4 180 897 616 230 1231 827 287 1617 1081 352 2069 1370 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 1126 696 298 1478 910 365 1920 1150 NA NA NA NA NA NA NA NA NA
4 192 952 644 244 1307 884 305 1719 1150 372 2211 1460 471 2737 1800 560 3319 2180 662 3957 2590
6 198 1050 772 252 1445 1072 313 1902 1390 380 2434 1770 478 3018 2180 568 3665 2640 669 4373 3130
10 2 196 870 536 249 1195 730 311 1570 955 379 2049 1205 NA NA NA NA NA NA NA NA NA
4 201 997 664 256 1371 924 318 1804 1205 387 2332 1535 486 2887 1890 581 3502 2280 686 4175 2710
6 207 1095 792 263 1509 1118 325 1989 1455 395 2556 1865 494 3169 2290 589 3849 2760 694 4593 3270
15 2 214 967 568 272 1334 790 336 1760 1030 408 2317 1305 NA NA NA NA NA NA NA NA NA
4 221 1085 712 279 1499 1006 344 1978 1320 416 2579 1665 523 3197 2060 624 3881 2490 734 4631 2960
6 228 1181 856 286 1632 1222 351 2157 1610 424 2796 2025 533 3470 2510 634 4216 3030 743 5035 3600
20 2 223 1051 596 291 1443 840 357 1911 1095 430 2533 1385 NA NA NA NA NA NA NA NA NA
4 230 1162 748 298 1597 1064 365 2116 1395 438 2778 1765 554 3447 2180 661 4190 2630 772 5005 3130
6 237 1253 900 307 1726 1288 373 2287 1695 450 2984 2145 567 3708 2650 671 4511 3190 785 5392 3790
30 2 216 1217 632 286 1664 910 367 2183 1190 461 2891 1540 NA NA NA NA NA NA NA NA NA
4 223 1316 792 294 1802 1160 376 2366 1510 474 3110 1920 619 3840 2365 728 4861 2860 847 5606 3410
6 231 1400 952 303 1920 1410 384 2524 1830 485 3299 2340 632 4080 2875 741 4976 3480 860 5961 4150
50 2 206 1479 689 273 2023 1007 350 2659 1315 435 3548 1665 NA NA NA NA NA NA NA NA NA
4 213 1561 860 281 2139 1291 359 2814 1685 447 3730 2135 580 4601 2633 709 5569 3185 851 6633 3790
6 221 1631 1031 290 2242 1575 369 2951 2055 461 3893 2605 594 4808 3208 724 5826 3885 867 6943 4620
100 2 192 1923 712 254 2644 1050 326 3490 1370 402 4707 1740 NA NA NA NA NA NA NA NA NA
4 200 1984 888 263 2731 1346 336 3606 1760 414 4842 2220 523 5982 2750 639 7254 3330 769 8650 3950
6 208 2035 1064 272 2811 1642 346 3714 2150 426 4968 2700 539 6143 3350 654 7453 4070 786 8892 4810
FAN
FAN
FAN
FAN
FAN
FAN
24 in.
Appliance Input Rating Limits in Thousands of Btu per Hour
Vent Connector Capacity
Vent
Height
H
(ft.)
Connec-
tor Rise
R
(ft.)
Type B Double-Wall Vent and Connector Diameter - D
12 in.
14 in.
FAN
16 in.
18 in.
20 in.
22 in.
Table 3 - Two or More Appliances (continued)
Capacity of Type B Double-Wall Vents with Type B Double-Wall
Connectors serving Two or More Category I Appliances
FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT
+FAN +NAT +NAT +FAN +NAT +NAT +FAN +NAT +NAT +FAN +NAT +NAT +FAN +NAT +NAT +FAN +NAT +NAT +FAN +NAT +NAT
6 900 696 588 1284 990 815 1735 1336 1065 2253 1732 1345 2838 2180 1660 3488 2677 1970 4206 3226 2390
8 994 773 652 1423 1103 912 1927 1491 1190 2507 1936 1510 3162 2439 1860 3890 2998 2200 4695 3616 2680
10 1076 841 712 1542 1200 995 2093 1625 1300 2727 2113 1645 3444 2665 2030 4241 3278 2400 5123 3957 2920
15 1247 986 825 1794 1410 1158 2440 1910 1510 3184 2484 1910 4026 3133 2360 4971 3862 2790 6016 4670 3400
20 1405 1116 916 2006 1588 1290 2722 2147 1690 3561 2798 2140 4548 3552 2640 5573 4352 3120 6749 5261 3800
30 1658 1327 1025 2373 1892 1525 3220 2558 1990 4197 3326 2520 5303 4193 3110 6539 5157 3680 7940 6247 4480
50 2024 1640 1280 2911 2347 1863 3964 3183 2430 5184 4149 3075 6567 5240 3800 8116 6458 4500 9837 7813 5475
100 2569 2131 1670 3732 3076 2450 5125 4202 3200 6749 5509 4050 8597 6986 5000 10681 8648 5920 13004 10499 7200
22 in.
24 in.
Combined Appliance Input Rating in Thousands of Btu per Hour
Common Vent Capacity
Vent
Height
H
(ft.)
Type B Double-Wall Vent Diameter - D
12 in.
14 in.
16 in.
18 in.
20 in.