Lennox G21Q Series Installation Instructions Manual page 11

ate Category 1 Natural Gas and Propane ap-
pliances venting sizing tables in the current stan-
dards of the CAN/CGA- -B149.1 and .2 in the Natural
Gas and Propane Installation Code in Canada.
E - - Intake and Exhaust Piping Terminations
Intake and exhaust pipes may be routed either hori-
zontally through an outside wall or vertically through
the roof. In attic or closet installations, vertical termi-
nation through the roof is preferred. Figures 7
through 18 show typical terminations.
3(76) MAX.
Inches(mm)
8 (203) MIN
12 (305) ABOVE
AVERAGE SNOW
ACCUMULATION
3 (76) OR
2 (51) PVC
PROVIDE SUPPORT
FOR INTAKE AND
EXHAUST LINES
ROOF TERMINATION KIT
(15F75) LB- -49107CC for 2 (51) Venting
(44J41) LB- -65678A for 3 (76) Venting
FIGURE 7
1 - - Use PVC pipe for both intake and exhaust piping
2 - - Secure all joints, including drain leg, gas tight us-
ing approved PVC solvent.
3 - - Piping diameters should be determined according
to length of pipe run. See table 4. Locate intake pip-
ing upwind (prevailing wind) from exhaust piping.
To avoid recirculation of exhaust gas on roof ter-
minations, end of exhaust pipe must be higher
than intake pipe.
Exhaust and intake exits must be in same pressure
zone. Do not exit one through the roof and one on
the side. Also, do not exit the intake on one side
and the exhaust on another side of the house or
structure.
4 - - Intake and exhaust pipes should be placed as close
together as possible at termination end (refer to il-
lustrations). Maximum separation is 3” (76mm) on
roof terminations and 6” (152mm) on side wall ter-
minations.
5 - - Exhaust piping must terminate straight out or up
as shown. On roof terminations, the intake piping
should terminate straight down using two 90
bows (See figure 7). In rooftop applications, a 2” X
3 x 2 (76 x 51) OR
2 x 1- -1/2 (51 x 38)
PVC REDUCER
1/2 (13) FOAM
INSULATION IN
UNCONDITIONED
SPACE
UNCONDITIONED
ATTIC SPACE
-
el-
3DJH 
1- -1/2” (51 x 38mm) reducer must be used on the
exhaust piping at the point where it exits the struc-
ture to improve the velocity of exhaust away from
the intake piping.
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NOTE - - If winter design temperature is below 32
exhaust piping must be insulated with 1/2” (13mm), Ar-
maflex or equivalent when run through unheated space.
Do not leave any surface area of exhaust pipe open to
outside air; exterior exhaust pipe must be insulated with
1/2” (13mm) Armaflex or equivalent. In extreme cold cli-
mate areas, 3/4” (19mm) Armaflex or equivalent is rec-
ommended. Insulation on outside runs of exhaust pipe
must be painted or wrapped to protect insulation from
deterioration.
NOTE - - During extremely cold temperatures, below
-
approximately 20 F (6.67
vent pipe through unconditioned space, even when in-
sulated, may form ice in the exhaust termination that
prevents the unit from operating properly. Longer run
times of at least 5 minutes will alleviate most icing
problems. A low ambient thermostat kit (70G49) can be
installed to increase run times. Also, a heating cable
may be installed on exhaust piping and termination to
prevent freeze- -ups. Heating cable installation kit is
available from Lennox. See Exhaust and Condensate
Piping section for part numbers.
6 - - On field supplied terminations for side wall exits,
exhaust piping should extend a minimum of 12”
(305mm) beyond the outside wall. Intake piping
should be as short as possible. See figure 8.
1/2 (13) ARMAFLEX
INSULATION IN
UNCONDITIONED SPACE
2 (51) PVC
1/2 (13) ARMAFLEX
INSULATION
OUTSIDE
WALL
TOP VIEW
Inches (mm)
WALL RING KIT
(15J74) LB- -49107CB for 2 (50.8) Venting
),*85( 
-
F (0
-
C), units with long runs of
12 (305) MIN.
2 X 1- -1/2
(51 x 38)
PVC REDUCER
1- -1/2 (38) PVC
6 (152)
MAXIMUM
2 (51) PVC
COUPLING
8 (203)
MINIMUM
-
C),