1-1/2 feet (.46 m) for each inch (25 mm) of common vent diameter.
10 − The vent pipe should be as short as possible with the least number of elbows and angles required to com- plete the job. Route the vent connector to the vent us- ing the shortest possible route.
11 − A vent connector shall be supported without any dips or sags and shall slope a minimum of 1/4 inch (6.4 mm) per linear foot (305 mm) of connector, back toward the appliance.
12 − Vent connectors shall be firmly attached to the furnace flue collar by self−drilling screws or other approved means, except vent connectors of listed type B vent material which shall be assembled according to the manufacturer’s instructions. Joints between sections of single wall connector piping shall be fastened by screws or other approved means.
13 − When the vent connector used for Category I ap- pliances must be located in or pass through a crawl- space, attic or other areas which may be cold, that por- tion of the vent connector shall be constructed of listed double-wall type B vent material or material having equivalent insulation qualities.
14 − All venting pipe passing through floors, walls, and ceil- ings must be installed with the listed clearance to com- bustible materials and be fire stopped according to lo- cal codes. In absence of local codes, refer to NFGC (Z223.1).
15 − No portion of the venting system can extend into, or pass through any circulation air duct or plenum.
INTERIOR TILE−LINED
MASONRY CHIMNEY
NOTE − the chimney must be properly sized per provided venting tables or lined with listed metal lining system.
PERMANENTLY SEALED FIREPLACE OPENING
Common Venting Using Tile−Lined Interior Masonry Chimney and Combined Vent Connector
MINIMUM LENGTH = AS SHORT AS PRACTICAL.
FOR MAXIMUM LENGTH SEE NOTE TO LEFT
NOTE− Refer to provided venting tables for installations.
FIGURE 25
6 − The entire length of single wall metal vent connector shall be readily accessible for inspection, cleaning, and replacement.
7 − Single appliance venting configurations with zero lat- eral lengths (tables 3 and 4) are assumed to have no elbows in the vent system. For all other vent configura- tions, the vent system is assumed to have two 90° el- bows. For each additional 90° elbow or equivalent (for example two 45° elbows equal one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10% (0.90 x maximum listed ca- pacity).
8 − The common venting tables (5, 6, 7, and 8) were gen- erated using a maximum horizontal vent connector length of 1−1/2 feet (.46 m) for each inch (25 mm) of connector diameter as follows:
TABLE 2
Connector Diameter | Maximum Horizontal |
inches (mm) | Connector Length feet (m) |
| |
| |
3 (76) | 4−1/2 (1.37) |
| |
4 (102) | 6 (1.83) |
| |
5 (127) | 7−1/2 (2.29) |
| |
6 (152) | 9 (2.74) |
| |
7 (178) | 10−1/2 (3.20) |
9 − If the common vertical vent is offset, the maximum common vent capacity listed in the common venting tables should be reduced by 20%, the equivalent of two 90° elbows (0.80 x maximum common vent capacity). The horizontal length of the offset shall not exceed
