c. If required per Table 7, insert perforated disk assembly
(factory-supplied in loose parts bag) in intake housing
where combustion-air intake pipe will be connected. If half
disk set is required, install with shoulder of disk against
stop in combustion-air inlet.
d. Install pipe support (factory-supplied in loose parts bag)
into selected furnace casing combustion-air pipe hole. Pipe
support should be positioned at bottom of casing hole.
e. Insert 2-in. diameter pipe into intake housing.
NOTE: A 2-in. diameter pipe must be used within the furnace
casing. Make all pipe diameter transitions outside furnace casing.
f. Install casing hole filler plug (factory-supplied in loose
parts bag) in unused combustion-air pipe casing hole.
g. Drill a 1/8-in. hole in 2-in. combustion-air pipe using hole
in intake housing as a guide.
h. Install a field-supplied No. 6 or No. 8 sheet metal screw
into combustion-air pipe.
NOTE: DO NOT OVERTIGHTEN SCREW. Breakage of intake
housing or fitting may cause air leakage to occur.
NOTE: Do not attach combustion-air intake pipe permanently to
combustion-air intake housing since it may be necessary to remove
pipe for service of ignitor or flame sensor.
COMBUSTION-AIR INTAKE HOUSING PLUG FITTING
The combustion-air intake plug fitting must be installed in unused
combustion-air intake housing. This fitting must be attached by
using RTV sealant, or by drilling a 1/8-in. hole in fitting, using
hole in intake housing as a guide. Install a field-supplied No. 6 or
No. 8 sheet metal screw.
NOTE: DO NOT OVERTIGHTEN SCREW. Breakage of intake
housing or fitting may cause air leakage to occur.
A plugged drain connection has been provided on this fitting for
use when moisture is found in combustion-air intake pipe and
combustion box.
NOTE: Moisture in combustion-air intake may be result of
improper termination. Ensure combustion-air intake pipe termina-
tion is similar to that shown in Fig. 36, 37, 38, 39, and 40 so it will
not be susceptible to areas where light snow or other sources of
moisture could be pulled in.
If use of this drain connection is desired, drill out fitting’s tap plug
with a 3/16-in. drill and connect a field-supplied 3/8-in. tube. This
tube should be routed to open condensate drain for furnace and
A/C (if used), and should be trapped. (See Fig. 35.)
2. Attach vent pipe to furnace as follows:
a. Determine location of vent pipe connection to inducer
housing as shown in Fig. 33 for application.
b. Reposition elastomeric (rubber) inducer housing outlet cap
and clamp to appropriate unused inducer housing connec-
tion. Tighten clamp.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in unit component
damage.
Inducer housing outlet cap must be installed and fully
seated against inducer housing. Clamp must be tightened to
prevent any condensate leakage.
c. Install pipe support (factory-supplied in loose parts bag)
into selected furnace casing vent pipe hole. Pipe support
should be positioned at bottom of casing hole.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in unit component
damage.
Vent pipe must be installed and fully seated against inducer
housing internal stop. Clamp must be tightened to prevent any
condensate leakage.
NOTE: A 2-in. diameter pipe must be used within the furnace
casing. Make all pipe diameter transitions outside furnace casing.
d. Be certain that mating surfaces of inducer housing connec-
tion, elastomeric coupling, and 2-in. diameter vent pipe are
clean and dry. Assemble the elastomeric (rubber) vent
coupling (with 2 loose clamps) onto inducer housing
connection. Insert the 2-in. diameter vent pipe through the
elastomeric (rubber) coupling and fully into inducer hous-
ing connection until it bottoms on the internal stop. Tighten
both clamps to secure the pipe to inducer housing. Tighten
the clamp screws to 15 in.-lb. of torque.
e. Install casing hole filler plug (factory-supplied in loose
parts bag) in unused combustion-air pipe casing hole.
VENT EXTENSION PIPE
Furnaces with 100,000 Btuh and larger inputs are supplied with a
PVC vent extension pipe (2-in. diameter by 12-in. long). This pipe
has a built-in channel to assist vent condensate disposal. When this
vent extension pipe is supplied, it must be used to connect the field
vent pipe to furnace inducer housing on ALL upflow and down-
flow applications.
NOTE: See label on vent extension pipe for proper installation.
This pipe may be shortened if an elbow is used to connect vent
extension tube to field-installed vent pipe.
Fig. 33—Combustion-Air and Vent Pipe
Connections
A96187
COMBUSTION-
AIR
COMBUSTION-
AIR
AIR
FLOW
VENT
VENT
VENT
AIR
FLOW
AIR
FLOW
AIR
FLOW
UPFLOW DOWNFLOW
HORIZONTAL-LEFT DISCHARGE HORIZONTAL-RIGHT DISCHARGE
Select 1 vent pipe connection and
1 combustion-air pipe connection.
COMBUSTION-
AIR
COMBUSTION-
AIR
COMBUSTION-
AIR
COMBUSTION-
AIR
VENT
VENT
VENT
NOTE: Select 1 vent pipe connection and
1 combustion-air pipe connection.
NOTE:
27
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