INSTALLATION CONSIDERATIONS
24
Horizontal vent/flue pipe terminations should be as shown in
the following figure. Refer to Vent/Flue Pipe and Combus-
tion Air Pipe - Termination Locations section in this manual
or the installation instructions for details concerning loca-
tion restrictions. A 2 3/8" diameter wall penetration is re-
quired for 2" diameter pipe while a 3 1/2" diameter hole is
required for 3" diameter pipe. To secure the pipe passing
through the wall and prohibit damage to piping connections,
a coupling should be installed on either side of the wall and
solvent cemented to a length of pipe connecting the two
couplings. The length of pipe should be the wall thickness
plus the depth of the socket fittings to be installed on the
inside and outside of the wall. The wall penetration should
be sealed with silicone caulking material.
In a basement installation, the vent/flue pipe can be run be-
tween joist spaces. If the vent pipe must go below a joist
and then up into the last joist space to penetrate the header,
two 45° elbows should be used to reach the header rather
than two 90° elbows.
NOTE: Terminate both pipes in the same pressure zone
(same side of roof, no major obstacle between pipes, etc).
COMBUSTION AIR INTAKE
(OPTIONAL)
*Not required for
single pipe installation
TEE (OPTIONAL)
9
6
”
M
A
X
.
-
3
”
M
I
N
.
R
O
O
F
L
I
N
E
INTAKE
SCREEN
OPTIONAL
12” MIN
HEIGHT DIFFERENCE
BETWEEN
INTAKE AND VENT
12” MIN TO ROOF OR HIGHEST
ANTICIPATED SNOW LEVEL
STRAIGHT
ELBOWS
12" MINIMUM
VENT/FLUE TEE
OR
90° ELBOW TURNED
DOWN
12" MINIMUM ABOVE
HIGHEST ANTICIPATED
SNOW LEVEL
90% Furnace Horizontal Termination (Single Pipe)
Above Highest Anticipated Snow Level
Direct Vent (Dual Pipe) Piping
Direct vent installations require both a combustion air in-
take 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 chim-
ney. The space between the pipes and the chimney must
be closed with a weather tight, corrosion resistant flashing.
Both the combustion air intake and a vent/flue pipe termina-
tions must be in the same atmospheric pressure zone. Re-
fer to Vent/Flue and Combustion Air Pipe - Termination Lo-
cations or Concentric Vent Termination section in this manual
or the installation instructions for specific details on termi-
nation construction.
12345678
40,000
2
or 2 1/2
120 115 110 105 100 95 90 85
60,000
2
or 2 1/2
95 90 85 80 75 70 65 60
80,000 "B" 2 or 2 1/2 75 70 65 60 55 50 45 40
80,000 "B" 3 200 193 186 179 172 165 158 151
80,000 "C" 2 or 2 1/2 25 20 15 10 5 N/A N/A N/A
80,000 "C" 3 200 193 186 179 172 165 158 151
100,000 2 or 2 1/2 25 20 15 10 5 N/A N/A N/A
100,000 3 200 193 186 179 172 165 158 151
120,000 2 or 2 1/2 45 40 35 30 25 20 15 10
120,000 3 95 90 85 80 75 70 65 60
*MVC96/*CVC96 Direct Vent (2 - Pipe) and Non-Direct Vent (1- Pipe)
(6)
Maximum Allowable Length of Vent/Flue Pipe
& Combustion Air Pipe (ft)
(1) (2)
Unit Input
(Btu)
Pipe Size
(4)
(in.)
Number of Elbows
(3) (5)
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