Page 14
8 - 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 caĆ
pacity). The horizontal length of the offset shall not exĆ
ceed 1Ć1/2 feet (.46 m) for each inch (25 mm) of comĆ
mon vent diameter.
9 - The vent pipe should be as short as possible with
the least number of elbows and angles required to
complete the job. The vent connector should be
routed to the vent using the shortest possible route.
10 - 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 toĆ
ward the appliance. See local and national installation
codes for support intervals and methods. National
installation code in the U.S.A is current edition of Na-
tional fuel Gas Code (ANSI–Z223.1). National installa-
tion codes in Canada are current editions of CAN/
CGA–B149 codes.
11 - Vent connectors shall be firmly attached to furnace
flue collars by screws or other approved means, exĆ
cept vent connectors of listed type B vent material
which shall be assembled according to the manufacĆ
turer's instructions. Joints between sections of single
wall connector piping shall be fastened by screws or
other approved means.
12 - When the vent connector used for Category I apĆ
pliances must be located in or pass through a crawlĆ
space or other areas which may be cold, that portion of
the vent connector shall be constructed of listed
doubleĆwall type B vent material or material having
equivalent insulation qualities.
13 - All venting pipe passing through floors, walls, and ceilĆ
ings must be installed with the listed clearance to comĆ
bustible materials and be fire stopped according to loĆ
cal codes. In absence of local codes, refer to NFGC
(Z223.1).
14 - No portion of the venting system can extend into, or pass
through any circulation air duct or plenum.
15 - Vent connectors serving Category I appliances shall
not be connected to any portion of mechanical draft
systems operating under positive pressure such as
Category III or IV venting systems.
16 - If vent connectors are combined prior to entering the
common vent, the maximum common vent capacity
listed in the common venting tables must be reduced by
10%, the equivalent of one 90_ elbow (0.90 x maximum
common vent capacity).
17 - The common vent diameter must always be at least as
large as the largest vent connector diameter.
18 - In no case, shall the vent connector be sized more
than two consecutive table size diameters over the
size of the draft hood outlet or flue collar outlet.
19 - Do not install a manual damper, barometric draft reguĆ
lator or flue restrictor between the furnace and the
chimney.
20 - When connecting this appliance to an existing dedicated
or common venting system, the venting system must be
inspected for signs of corrosion and general condition.
The sizing of the vent system must be reviewed and
must conform to these instructions and the provided
venting tables for the USA, and the appropriate venting
tables in the standards of CAN/CGA B149.1 and
B149.2 of the Natural Gas and Propane Installation
Code for Canada. If the existing system is in conflict with
these requirements, the venting system must be reĆ
sized.
To Next Page
Loading...
