Carrier 58MXA Installation, Start-Up, And Operating Instructions Manual page 27

EXAMPLE: An 080-12 size furnace located in Indianapo-
lis, elevation 650 ft above sea level, could be installed in an
application requiring 3 elbows and 32 ft of vent pipe, along
with 5 elbows and 34 ft of combustion-air pipe. Table 7
indicates this application would allow a 2-in. diameter vent
pipe, but require a 2-1/2 in. diameter combustion air pipe
(2-in. pipe is good for 35 ft with 3 elbows, but only 30 ft
with 5 elbows). Therefore, 2-1/2 in. diameter pipe must be
used for both vent and combustion-air pipes since larger
required diameter must always be used for both pipes. If
same installation were in Albuquerque, elevation 5250 ft
above sea level, installation would require 2-1/2 in. vent
pipe and combustion-air pipe. At 5001- to 6000-ft eleva-
tion, 2-in. pipe is only good for 17 ft with 5 elbows, and
2-1/2 in. pipe is good for 70 ft with 5 elbows.
Combustion-Air and Vent Pipe Attachment
NOTE: All pipe joints must be cemented except attachment of
combustion-air pipe to inlet housing connection, since it may be
necessary to remove pipe for servicing.
1. Attach combustion-air pipe as follows:
a. Determine location of combustion-air intake pipe connec-
tion to combustion-air intake housing as shown in Fig. 33
for application.
b. Reposition combustion-air intake housing plug fitting in
appropriate unused intake housing connection.
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.)
3/8" ID TUBE
3/16"
DRILL
4"
MIN
TRAP
TO OPEN
DRAIN
Fig. 35—Air Intake Housing Plug Fitting Drain
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.
Inducer housing outlet cap must be installed and fully seated
against inducer housing. Clamp must be tightened to prevent
any condensate leakage. Failure to follow this warning could
result in electrical shock, fire, personal injury, or death.
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.
Vent pipe must be installed and fully seated against inducer
housing internal stop. Clamp must be tightened to prevent any
condensate leakage. Failure to follow this warning could
result in electrical shock, fire, personal injury, or death.
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.
27
COMBUSTION – AIR
INTAKE HOUSING
BURNER
BOX
COMBUSTION –
AIR PIPE
A93035