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Use the steps in Figure 16 to correctly size vent pipe
diameter.
Furnace capacity?
1
Which termination?
2
Which needs most
3
elbows?
How many?
4
Desired pipe size?
5
What is the altitude?
6
Use Table 6 to find
7
max pipe length.
Figure 16.
General Guidelines for Vent Terminations
In Direct Vent applications, combustion air is taken from
outdoors and the flue gases are discharged to the outdoors.
This gas furnace is classified as a direct vent, Category IV
gas furnace.
In Direct Vent applications, the vent termination is limited
by local building codes. In the absence of local codes,
refer to the current National Fuel Gas Code ANSI Z223-1/
Page 14 of 74
NFPA 54 in U.S.A., and current CSA-B149 Natural Gas
and Propane Installation Codes in Canada for details.
Position termination according to location given in
Figure 20. In addition, position termination so it is free
from any obstructions and 12" above the average snow
070, 090,
accumulation.
110 or 135
btuh
At vent termination, care must be taken to maintain
protective coatings over building materials (prolonged
exposure to exhaust condensate can destroy protective
coatings). It is recommended that the exhaust outlet not be
located within 6 feet (1.8m) of a condensing unit because
Standard or
the condensate can damage the painted coating.
Concentric?
See Table 3
NOTE: See Table 5 for maximum allowed exhaust pipe
length without insulation in unconditioned space during
winter design temperatures below 32°F (0°C). If required,
exhaust pipe should be insulated with 1/2" (13mm)
ArmaFlex
3/4" (19mm) ArmaFlex
Intake or
Insulation on outside runs of exhaust pipe must be painted
Exhaust?
or wrapped to protect insulation from deterioration. Exhaust
pipe insulation may not be necessary in some specific
applications.
FOR CANADIAN INSTALLATIONS ONLY:
In accorddance to CSA International B149 installation
codes, the minimum allowed distance between the
1-1/2", 2",
combustion air intake inlet and the exhaust outlet of
2-1/2"
other appliances shall not be less than 12 inches (305
or 3"
mm).
Issue 2346
or equivalent. In extreme cold climate areas,
®
or equivalent may be necessary.
®
IMPORTANT
Conditioned
Space
Conditioned
Unconditioned
Space
Figure 17. Insulating Exhaust Pipe in an
Unconditioned Space
Exhaust
Pipe
Pipe Insulation
Intake
Pipe
Space
508364-01
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