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NON-DIRECT VENT (SINGLE PIPE) PIPING
Non-direct vent installations require only a vent/flue pipe.
The vent pipe can be run horizontally with an exit through
the side of the building or run vertically with an exit through
the roof of the building. The vent can also be run through
an existing unused chimney; however, it must extend a
minimum of 12 inches above the top of the chimney. The
space between the vent pipe and the chimney must be
closed with a weather-tight, corrosion-resistant flashing.
For details concerning connection of the vent/flue pipe to
the furnace, refer to Section IX, Vent/Flue Pipe and Com-
bustion Air - Standard Furnace Connections or Alternate
Furnace Connections for specific details. Refer to the
following Non-Direct Vent (Single Pipe) Piping - Vent/Flue
Pipe Terminations for specific details on termination con-
struction.
Although non-direct vent installations do not require a
combustion air intake pipe, a minimum of one 90° elbow
must be attached to the furnace's combustion air intake if:
an upright installation uses the standard intake location, or
a horizontal installation uses the alternate air intake loca-
tion. This elbow will guard against inadvertent blockage of
the air intake.
Vent/Flue Pipe Lengths and Diameters
Refer to the following table for applicable length, elbows,
and pipe diameter for construction of the vent/flue pipe
system of a non-direct vent installation. In addition to the
vent/flue pipe, a single 90° elbow must be secured to the
combustion air intake to prevent inadvertent blockage. The
tee used in the vent/flue termination must be included when
determining the number of elbows in the piping system.
Non-Direct Vent (Single Pipe)
Maximum Allowable Length of Vent/Flue Pipe (ft)
Unit Input
Pipe
(BTU)
(4)
Size
(inc.)
2
45,000
2
68
70,000
2
68
90,000
2
60
2
25
115,000
3
58
(1) One 90° elbow must be secured to the combustion air intake
connection.
(2) Minimum vent length is five feet and one elbow/tee.
(3) Tee used in the vent/flue termination must be included when
determining the number of elbows in the piping system.
(4) 3" diameter pipe can be used in place of 2" diameter pipe.
Vent/Flue Pipe Terminations
The vent/flue pipe may terminate vertically, as through a
roof, or horizontally, as through an outside wall.
Vertical vent/flue pipe terminations should be as shown in
the following figure. Refer to Section IX, Vent/Flue Pipe and
Combustion Air Pipe - Termination Locations for details
concerning location restrictions. The penetration of the
vent through the roof must be sealed tight with proper
flashing such as is used with a plastic plumbing vent.
(1) (2)
(3)
Number of Elbows
3
4
5
6
7
65
62
59
56
53
65
62
59
56
53
57
55
52
50
47
22
20
17
15
12
55
52
49
46
43
Vertical Termination (Single Pipe)
12" Min.
Alternate Vertical Termination (Single Pipe)
Horizontal vent/flue pipe terminations should be as shown
in the following figure. Refer to Section IX, Vent/Flue Pipe
and Combustion Air Pipe - Termination Locations for details
concerning location restrictions. A 2 3/8" diameter wall
penetration is required for 2" diameter pipe while a 3 1/2"
diameter hole is required for 3" diameter pipe. To secure
8
the pipe passing through the wall and prohibit damage to
50
piping connections, a coupling should be installed on either
50
side of the wall and solvent cemented to a length of pipe
connecting the two couplings. The length of pipe should be
45
the wall thickness plus the depth of the socket fittings to be
10
installed on the inside and outside of the wall. The wall
40
penetration should be sealed with silicone caulking material.
INSIDE
ELBOW OR
COUPLING
Horizontal Termination (Single Pipe)
18
TEE
12 " Min To
Roof Or
Highest Anticipated
Snow Level
90º
Medium Radius
Elbow
WALL
OUTSIDE
COUPLING
MIN.
12"
FROM
WALL
TO GROUND OR
HIGHEST ANTICIPATED
SNOW LEVEL
TEE
or
90°ELBOW
TURNED
DOWN
12"
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