Carrier 58MTA Installation, Start-Up, And Operating Instructions Manual page 28

a. Determine location of combustion-air intake pipe connec-
tion to combustion-air intake housing as shown in Fig. 34
for application.
b. Reposition combustion-air intake housing plug fitting in
appropriate unused intake housing connection.
c. If required (See 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 igniter 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
NOTE: Select 1 vent pipe connection and
1 combustion-air pipe connection.
AIR
FLOW
COMBUSTION- COMBUSTION-
AIR AIR
VENT
VENT
UPFLOW
COMBUSTION-
AIR
VENT
AIR
FLOW
HORIZONTAL-LEFT DISCHARGE
Fig. 34—Combustion-Air and Vent Pipe Connections
NOTE: Select 1 vent pipe connection and
1 combustion-air pipe connection.
VENT
VENT
COMBUSTION- COMBUSTION-
AIR AIR
AIR
FLOW
DOWNFLOW
COMBUSTION-
AIR
VENT
AIR
FLOW
HORIZONTAL-RIGHT DISCHARGE
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. 37, 38, 39, 40, and 41 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. 36.)
2. Attach vent pipe to furnace as follows:
a. Determine location of vent pipe connection to inducer
housing as shown in Fig. 34 for application.
b. Reposition elastomeric (rubber) inducer housing outlet cap
and clamp to appropriate unused inducer housing connec-
tion. Tighten clamp.
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