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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/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 accumulation.
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
the condensate can damage the painted coating.
NOTE: See Table 6 for maximum allowed exhaust pipe
length without insulation in unconditioned space during
Maximum Allowable Vent pipe Length without Insulation in Unconditioned Space for Winter Design
Winter Design Temperatures
ºF (ºC)
32 to 21
(0 to -6)
20 to 1
(-7 to -17)
0 to -20
(-18 to -29)
Refer to 99% Minimum Design Temperature table provided in the current edition of the ASHRAE Fundamentals Handbook.
1
Poly-Propylene vent pipe (PP) by Duravent and Centrotherm
2
NOTE - Concentric terminations are the equivalent of 5' and should be considered when measuring pipe length.
NOTE- Maximum uninsulated vent lengths listed may include the termination (vent pipe exterior to the structure ) and cannot
exceed 5 linear feet or the maximum allowable intake or exhaust vent length listed in table 5 or 6.
NOTE - If insulation is required an unconditioned space, it must be located on the pipe closed to the furnace.
Page 20 of 74
Temperatures Modulating High Efficiency Furnace
1
Vent Pipe
Diameter
PVC
2 in.
11
2-1/2 in.
7
3 in.
N/A
2 in.
N/A
2-1/2 in.
N/A
3 in.
N/A
2 in.
N/A
2-1/2 in.
N/A
3 in.
N/A
Table 6
Issue 1622
winter design temperatures below 32°F
exhaust pipe should be insulated with
Armaflex or
equivalent.
3/4"
(19mm) Armaflex or equivalent may be
Insulation on outside runs of exhaust pipe must be painted
or wrapped to protect insulation from
pipe insulation may not be necessary in some specific
applications.
Do not use screens or perforated metal in exhaust
terminations. Doing so will cause freeze-ups and may
block the terminations.
FOR CANADIAN INSTALLATIONS ONLY:
In accorddance to CSA International B149 installation
codes, the minimum allowed distance between the
combustion air intake inlet and the exhaust outlet of
other appliances shall not be less than 12 inches (305
mm).
070
090
PP
PVC
PP
2
2
9
14
12
N/A
10
N/A
N/A
6
6
N/A
6
4
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
(O°C).
1/2"
In extreme cold climate
deterioration.
IMPORTANT
IMPORTANT
110
135
PVC
PP
PVC
2
18
15
N/A
12
N/A
N/A
8
8
13
8
6
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
If equired
(13mm)
areas,
necessary.
Exhaust
PP
2
N/A
N/A
13
N/A
N/A
N/A
N/A
N/A
N/A
507028-03
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