Lenox Lennox Merit Series Gas Furnace Upflow/Horizontal air discharge, ML180UHE 1/2

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.

OTHER

APPLIANCE

VENT

CONNECTOR

FURNACE

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

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