6. Install a field-supplied No. 6 or No. 8 sheet metal screw into combustion air pipe.
7. Install casing hole filler cap (factory-supplied in loose parts bag) in unused combustion air pipe casing hole.
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.
ATTACHMENT OF COMBUSTION AIR INTAKE HOUSING PLUG FITTING
The combustion-air intake plug fitting must be installled 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 combustion 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.
F.
Vent Pipe
GENERAL
Furnace vent connection must be attached as shown in Fig. 35.
WARNING: 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 condensate 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. 40)
ATTACHMENT OF VENT PIPE
1. Determine vent pipe diameter and maximum pipe lengths using Table 11.
NOTE:
(Direct Vent/2-Pipe) vent pipe system has the same diameter and same length as combustion air pipe as mentioned in section
″
Assembly
of Combustion Air Pipe (Direct Vent/2-Pipe system ONLY).
″
NOTE:
Do not count elbows or pipe sections in terminations or within furnace, as indicated as shaded areas in Fig. 40 for Direct Vent/2-Pipe
system, and Fig. 41 for Non-Direct Vent/1-Pipe system.
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.
CAUTION: 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.
Fig. 39—Intake Housing Plug Fitting Drain
A96190
COMBUSTION–
AIR PIPE
BURNER
BOX
COMBUSTION–AIR
INTAKE HOUSING
3/8
″
ID TUBE
TRAP
TO OPEN
DRAIN
3/16
″
DRILL
HOUSING
PLUG
4
″
MIN
Fig. 38—Vent Pipe Diameter Transition Location
and Elbow Configuration
A93034
FURNACE
PIPE DIAMETER
TRANSITION IN
VERTICAL SECTION
NOT IN
HORIZONTAL
SECTION
—43—
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