4. Permanently attach elbow/perforated disk assembly to straight portion of pipe using RTV or by cementing as shown in Fig. 36.
ASSEMBLY OF COMBUSTION AIR PIPE (DIRECT VENT-2-PIPE SYSTEM ONLY)
1. Using Table 11, determine the smallest combustion air diameter permitted. Pick the larger diameter and use it for both combustion and vent
pipe.
NOTE:
Do not count elbows or pipe sections in terminations or within furnace. See shaded areas in Fig. 40 for Direct Vent/2-Pipe system, and
Fig. 41 for Non-Direct Vent/1-Pipe system.
CAUTION: UNIT MAY NOT OPERATE
Failure to follow this caution may result in incomplete combusiton, flame disturbance, or flame sense lockout.
When installing combusiton air and vent system of short pipe length, the smallest allowable pipe diameter must be used.
NOTE:
A 2-in. diameter pipe must be used within furnace casing. Make all pipe diameter transitions outside furnacec casing per Fig. 37.
2. If required per Table 11, insert perforated disk assembly (factory-supplied in loose parts bag) in intake housing where combustion air pipe
will be connected. If half disk set is required, install only shouldered disk half.
ATTACHMENT OF COMBUSTION AIR PIPE
1. Determine location of combustion air intake pipe connection to combustion air intake housing as shown in Fig. 35 for application.
2. Reposition combustion air intake housing plug fitting in appropriate unused intake housing connection.
3. 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.
4. Insert assembled combustion air inlet pipe into intake housing as shown in Fig. 35.
5. Drill a 1/8-in. hole in 2-in, combustion air pipe using the hole in intake housing as a guide.
Fig. 36—Combustion-Air and Vent Pipe Connections
CAUTION: 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.
A96188
COMBUSTION-
AIR
COMBUSTION-
AIR
AIR
FLOW
VENT
VENT
VENT
AIR
FLOW
AIR
FLOW
AIR
FLOW
UPFLOW
DOWNFLOW
HORIZONTAL-LEFT DISCHARGE
HORIZONTAL-RIGHT DISCHARGE
Select 1 vent pipe connection and
1 combustion-air pipe connection.
COMBUSTION-
AIR
COMBUSTION-
AIR
COMBUSTION-
AIR
COMBUSTION-
AIR
VENT
VENT
VENT
NOTE:
Select 1 vent pipe connection and
1 combustion-air pipe connection.
NOTE:
* For Non-Direct Vent (1-Pipe) system, orient elbow so that its
opening faces down.
** For Non-Direct Vent (1-Pipe) system, orient elbow so that its
opening faces sideways.
† An external trap kit (see furnace product data sheet) must be used.
*
*
**
**
†
†
Fig. 37—Combustion-Air Inlet Pipe Assembly
Length of Straight Pipe Portion of
Combustion-Air Inlet Pipe Assembly (In.)
CASING WIDTH
A
17-1/2
8-1/2
±
1/2
21
10-1/2
±
1/2
24-1/2
12
±
1/2
A96211
FIELD-SUPPLIED
2-IN. DIAMETER
PVC PIPE
FIELD-SUPPLIED
2-IN. DIAMETER
PVC 90
°
ELBOW
COMBUSTION-AIR DISC
(FACTORY-SUPPLIED IN
LOOSE PARTS BAG)
A
—39—
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