Carrier 58MCB Installation, Start-Up, And Operating Instructions Manual page 37

FURNACE
NOT IN
HORIZONTAL
SECTION
Fig. 37—Combustion-Air and Vent Pipe Diameter
Transition Location and Elbow Configuration
Attachment of 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. If use of this drain connection is desired, drill out
fitting's tap plug with 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, as shown in
Fig. 38.
NOTE: (Direct Vent/2-Pipe System ONLY) Moisture in combus-
tion air intake may be a result of improper termination. Ensure
combustion air pipe termination is similar to those as shown in Fig.
40 so that it will not be susceptible to area where light snow or
others sources of moisture could be pulled in.
→
VENT PIPE
General
Furnace vent connection must be attached as shown in Fig. 35.
CARBON MONOXIDE POISONING AND PROPERTY
DAMAGE HAZARD
Failure to follow this warning could result in property
damage, personal injury, or death.
Vent pipes must be airtight.
NOTE: A 2-in. diameter pipe must be used within the furnace
casing. Make all pipe diameter transitions outside furnace casing
per Fig. 37.
The minimum vent pipe length for these furnaces is 5 ft. Short pipe
lengths (5-8 ft) may discharge condensate droplets. These conden-
sate droplets may be undesirable. A 12-in. minimum offset pipe
section is recommended to reduce excessive condensate droplets
from exiting vent pipe outlet. (See Fig. 39)
Attachment of Vent Pipe
1. Determine vent pipe diameter and maximum pipe lengths
using Table 11.
NOTE: (Direct Vent/2-Pipe ONLY) vent pipe system has the
same diameter and same length as combustion air pipe as men-
tioned in section "Assembly of Combustion Air Pipe (Direct
Vent/2-Pipe system ONLY)."
PIPE DIAMETER
TRANSITION IN
VERTICAL SECTION
A93034
3/8 ID TUBE
3/16
DRILL
4"MIN
TRAP
TO OPEN
DRAIN
→
Fig. 38—Air Intake Housing Plug
Fitting Drainage
NOTE: Do not count elbows or pipe sections in terminations or
within furnace (all elbows shown in Fig. 40 and Fig. 41 are not be
counted).
2. Determine location of vent pipe connection to inducer housing
as shown in Fig. 35 for application.
3. Reposition elastomeric (rubber) inducer housing outlet cap
and clamp to appropriate unused inducer housing connection.
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.
4. 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.
5. Be certain that mating surfaces of inducer housing connection
elastomeric (rubber) coupling, and 2-in. diameter vent pipe are
clean and dry. Assemble the elastomeric (rubber) vent cou-
pling (with 2 loose clamps) onto inducer housing connection.
Insert the 2-in. diameter vent pipe through the elastomeric
(rubber) coupling and fully into inducer housing connection
until it touches a stop inside the inducer housing outlet.
Tighten the screws on both clamps to 15-in-lb. of torque. pipe
to inducer housing. Tighten the clamp screws to 15 in.-lb. of
torque.
NOTE: Starting at furnace, slope vent pipe a minimum of 1/4-in.
per linear ft with no sags between hangers.
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.
6. Install casing hole filler cap (factory-supplied in loose parts
bag) in unused vent pipe casing hole.
37
COMBUSTION – AIR
INTAKE HOUSING
BURNER
BOX
COMBUSTION-AIR
PIPE (DIRECT
VENT/2 PIPE)
COMBUSTION-AIR
PIPE (NON-DIRECT
VENT/1-PIPE)
A05093