17
12 " Min To
Roof Or
Highest Anticipated
Snow Level
TEE
Vertical Termination (Single Pipe)
12" MIN.
TO ROOF OR
HIGHEST
ANTICIPATED
SNOW LEVEL
90º
MEDIUM RADIUS
ELBOWS
Alternate Vertical Termination (Single Pipe)
MIN.
12"
FROM
WALL
12"
TO GROUND OR
HIGHEST ANTICIPATED
SNOW LEVEL
WALL
INSIDE
OUTSIDE
TEE
or
90°ELBOW
TURNED
DOWN
COUPLING
ELBOW OR
COUPLING
Horizontal Termination (Single Pipe)
VENT/FLUE TEE
or
90° ELBOW TURNED
DOWN
12" MIN. ABOVE
HIGHEST ANTICIPATED
SNOW LEVEL
12" MIN.
Horizontal Termination (Single Pipe)
Above Highest Anticipated Snow Level
D
IRECT
V
ENT
(D
UAL
P
IPE
) P
IPING
The inlet air screens provided in the installation instruction packet
are available for the installer to use in the inlet of the combustion air
pipe to prevent animals from building nests in the combustion air
pipe. Installation of screens, while strongly recommended, is not
required and will not affect performance of the unit.
Direct vent
installations require both a combustion air intake and a
vent/flue pipe. The pipes may be run horizontally and exit through
the side of the building or run vertically and exit through the roof of
the building. The pipes may be run through an existing
unused
chimney; however, they must extend a minimum of 12 inches above
the top of the chimney. The space between the pipes and the chim-
ney must be closed with a weather tight, corrosion resistant flash-
ing. Both the combustion air intake and a vent/flue pipe termina-
tions must be in the same atmospheric pressure zone. Refer to
Section IX, Vent/Flue and Combustion Air Pipe - Termination Loca-
tions or Concentric Vent Termination
for specific details on termina-
tion construction. For details concerning connection of pipes to the
furnace, refer to the
Section IX, Vent/Flue Pipe and Combustion
Pipe - Standard Furnace Connections or Alternate Furnace Con-
nections.
V
ENT
/F
LUE
AND
C
OMBUSTION
A
IR
P
IPE
L
ENGTHS
AND
D
IAMETERS
Refer to the following table for applicable length, elbows, and pipe
diameter for construction of the vent/flue and combustion air intake
pipe systems of a direct vent (dual pipe) installation. The number of
elbows tabulated represents the number of elbows and/or tees in
each (Vent/Flue & Combustion Air Intake) pipe. Elbows and/or tees
used in the terminations must be included when determining the
number of elbows in the piping systems.
If the combustion air intake pipe is to be installed above a finished
ceiling or other area where dripping of condensate will be objection-
able, insulation of the combustion air pipe may be required. Use
1/2” thick closed cell foam insulation such as Armaflex or Insultube
where required.
Pipe
Size
(4)
(in.)
2
3
4
5
6
7
8
Standard
2
68
65
62
59
56
53
50
Alternate
2
55
52
49
46
43
40
37
Standard
2
68
65
62
59
56
53
50
Alternate
2
55
52
49
46
43
40
37
Standard
2
55
52
49
46
43
40
37
Alternate
2
42
39
36
33
30
27
24
Standard
2
26
23
20
Alternate
2
7
10
Standard
3
88
87
80
76
72
68
64
Alternate
3
74
70
66
62
58
54
50
Dire ct Ve nt (Dua l Pipe )
Maximum Allowable Length of Vent/Flue & Combustion
Air Intak e Pipe (ft)
Unit Input
(Btu)
Num ber of Elbows
(1)(2)(3)(5)
115,000
Not Recom mended
Vent/Flue/Air
Intake
Termination
45,000
70,000
90,000
115,000
Not Recomm ended
1) One 90° elbow should be secured to the combustion air intake connec-
tion.
2) Minimum requirement for each vent pipe is five (5) feet in length and one
elbow/tee.
3) Tee used in the vent/flue termination must be included when determin-
ing the number of elbows in the piping system.
4) 3” diameter pipe can be used in place of 2” diameter pipe.
5) Increased Clearance Configurations using (2) 45 deg. Long Sweep el-
bows should be considered equivalent to one 90 deg. elbow.
V
ENT
/F
LUE
AND
C
OMBUSTION
A
IR
P
IPE
T
ERMINATIONS
The vent/flue and combustion air pipes may terminate vertically, as
through a roof, or horizontally, as through an outside wall.
Vertical pipe terminations should be as shown in the following fig-
ure.
Refer to Section IX, Vent/Flue Pipe and Combustion Pipe -
Termination Locations
for details concerning location restrictions.
The penetrations through the roof must be sealed tight with proper
flashing such as is used with a plastic plumbing vent.
TEE
12" MIN.
12" MIN.
TO ROOF OR
HIGHEST
ANTICIPATED
SNOW LEVEL
VENT/FLUE
90º
MEDIUM RADIUS
ELBOWS
COMBUSTION
AIR INTAKE
24" MAX.
3" MIN.
SCREEN
Vertical Terminations (Dual Pipe)
Horizontal terminations should be as shown in the following figure.
Refer to
Section IX, Vent/Flue Pipe and Combustion Pipe - Termi-
nation Location
for location restrictions. A 2 3/8 inch diameter wall
