Carrier 58MCB Installation, Start-Up, And Operating Instructions Manual page 32

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Table 10—Maximum Allowable Exposed Vent Pipe Length (ft) With and Without Insulation in Winter Design
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 11.
† Insulation thickness based on R value of 3.5 per in.
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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 termi-
nate 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. 35.)
Maintain a 3-in minimum clearance between the opening of the
combustion-air inlet pipe and any object.
Temperature Ambient*
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
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
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.
pipe. Pick the larger of these 2 pipe diameters and use this
diameter for both combustion-air and vent pipes.
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.
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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