Carrier 58MSA Installation, Start-Up, And Operating Instructions Manual page 33

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
UNIT MAY NOT OPERATE
Failure to follow this caution may result in intermittent unit
operation.
Make sure there is adequate clearance (3-in. minimum) to any
fixed or loose objects in order to ensure an adequate
combustion-air supply.
Fig. 34—Combustion-Air and Vent Pipe
Connections
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. 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.)
Vent Pipe
NOTE: Furnace vent pipe connections are sized for 2-in. pipe.
Any vent pipe size change should be made outside furnace casing
in vertical pipe. (See Fig. 37.) This allows proper drainage of vent
condensate.
Determine vent pipe diameter and maximum pipe lengths using
Table 8.
Furnace vent pipe connection must be attached as shown in Fig.
34. Inducer housing alternate vent cap may need to be relocated in
some applications.
NOTE: Select 1 vent pipe connection and
1 combustion-air pipe connection.
VENT
VENT
COMBUSTION- COMBUSTION-
AIR
AIR AIR
FLOW
DOWNFLOW
COMBUSTION-
VENT
AIR
AIR
FLOW
HORIZONTAL-RIGHT DISCHARGE
A96188
FIELD-SUPPLIED
2-IN. DIAMETER
PVC 90° ELBOW
COMBUSTION-AIR DISC
(FACTORY-SUPPLIED IN
LOOSE PARTS BAG)
Length of Straight Pipe Portion of
Combustion-Air Inlet Pipe Assembly (In.)
CASING WIDTH
17-1/2
21
24-1/2
Fig. 35—Combustion-Air Inlet Pipe Assembly
HOUSING
PLUG
"
3/8 ID TUBE
"
3/16
DRILL
4"
MIN
TRAP
TO OPEN
DRAIN
Fig. 36—Air Intake Housing Plug Fitting Drain
NOT IN
HORIZONTAL
SECTION
Fig. 37—Vent Pipe Diameter Transition Location
and Elbow Configuration
NOTE: Starting at furnace, slope vent pipe a minimum of 1/4 in.
per linear ft upward to termination(s) with no sags between
hangers.
33
FIELD-SUPPLIED
2-IN. DIAMETER
PVC PIPE
A
A
8-1/2 ± 1/2
10-1/2 ± 1/2
12 ± 1/2
COMBUSTION–AIR
INTAKE HOUSING
BURNER
BOX
COMBUSTION–
AIR PIPE
FURNACE
PIPE DIAMETER
TRANSITION IN
VERTICAL SECTION
A96211
A96190
A93034