Payne PG9MAB Series A Installation Manual page 38

Table 10—Maximum Allowable Exposed Vent Pipe Length (ft) With and Without Insulation in Winter Design Temperature
FURNACE
SIZE
040
060
080
100
120
140
* Pipe length (ft) specified for maximum pipe lengths located in unconditioned spaces. Pipes located in unconditioned space cannot exceed total allowable pipe length as
specified in Table 10.
† Insulation thickness based on R value of 3.5 per in.
→
E. Combustion Air Pipe
GENERAL
Furnace combustion-air connection must be attached as shown in Fig. 35. Combustion-air intake housing plug may need to be relocated in some
applications.
For Non-Direct Vent (1-Pipe) system, combustion-air must terminate outside of furnace casing with 1 elbow. Orient elbow so that its opening faces
down for upflow or downflow applications. Orient elbow so that its opening faces sideways (left or right) for horizontal left or horizontal right
applications (See Fig. 36.) Maintain a 3-in minimum clearance between the opening of the combustion-air inlet pipe and any object.
CAUTION: UNIT CORROSION HAZARD
Excessive exposure to contaminated combustion air may result in safety and performance related problems.
Combustion air must not be taken from inside structure because inside air is frequently contaminated by halogens, which include
fluorides, chlorides, bromides, and iodides. These elements are found in aerosols, detergents, bleaches, cleaning solvents, salts, air
fresheners, adhesives, paint, and other household products. Locate combustion-air inlet as far as possible from swimming pool and
swimming pool pump house.
NOTE: All pipe joints must have cemented attachment of combustion-air inlet pipe to inlet housing connection, since it may be necessary to
remove pipe for servicing.
ASSEMBLY OF COMBUSTION AIR PIPE (NON-DIRECT VENT/1-PIPE SYSTEM ONLY)
1. Permanently install perforated disk assembly (factory-supplied in loose parts bag) in combustion-air elbow using RTV or by cementing, as
shown in Fig. 36. For 120,000 Btuh size units only: separate the 2 halves of perforated disk assembly and use only the shouldered disk half.
2. Determine the length of straight portion of combustion-air inlet pipe from Fig. 36.
3. Cut field-supplied 2-in. diameter PVC pipe to length as determined per Fig. 36.
WINTER DESIGN
TEMPERATURE
(°F)
20
0
-20
20
0
-20
20
0
-20
20
0
-20
20
0
-20
20
0
-20
20
0
-20
20
0
-20
20
0
-20
20
0
-20
20
0
-20
Ambient*
MAX PIPE
WITHOUT
DIAMETER
INSULATION
(IN.)
1.5 51
1.5 28
1.5 16
2 45
2 22
2 10
2 65
2 35
2 20
2 55
2 48
2 30
2.5 70
2.5 47
2.5 28
2.5 40
2.5 40
2.5 38
3 70
3 50
3 28
3 70
3 61
3 37
4 70
4 48
4 23
3 60
3 60
3 44
4 70
4 57
4 30
—38—
WITH 3/8–IN. OR
THICKER INSULATION†
70
70
70
70
70
58
70
70
70
55
55
55
70
70
70
40
40
40
70
70
70
70
70
70
70
70
70
60
60
60
70
70
70