F97CMN and G97CMN: Installation, Start-up, Operating and Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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1. Using winter design temperature (used in load calculations), find
appropriate temperature for your application and furnace model.
2. Determine the amount of total and exposed vent pipe.
3. Determine required insulation thickness for exposed pipe length(s).
4. When combustion air inlet piping is installed above a suspended
ceiling, the pipe
MUST
be insulated with moisture resistant
insulation such as Armaflex or other equivalent type of insulation.
5. Insulate combustion air inlet piping when run in warm, humid
spaces.
6. Install the insulation per the insulation manufacturer’s installation
instructions.
NOTE:
Pipe length (ft. / M) specified for maximum pipe lengths located
in unconditioned spaces cannot exceed total allowable pipe length as
.
A170122A
Fig. 49 – Recommended Combustion Air Inlet Moisture Trap
NOTE:
Maximum Equivalent Vent Length (MEVL) includes standard and concentric vent termination and does NOT include elbows. Use
Deductions from Maximum Equivalent Vent Length to determine allowable vent length for each application.
Table 11 – Maximum Equivalent Vent Length - Ft.
Ft.
Unit Size
60,000
80,000
100,000
120,000
Altitude
(feet)
Pipe Dia. (in)
1
½
2
2
½
3
1
½
2
2
½
3
4
2
2
½
3
4
2
½
3
4
0-2000
50
100
175
200
30
95
130
175
200
45
80
175
200
10
75
185
2001-3000
45
95
165
185
70
125
165
185
40
75
165
185
70
175
3001-4000
40
90
155
175
25
115
155
175
38
155
175
5
65
165
4001-4500
35
85
150
170
23
110
150
165
36
70
170
N/A
60
160
4501-5000
80
165
22
145
160
150
165
5001-6000
37
75
140
155
100
135
150
33
140
155
155
6001-7000
35
70
130
145
20
90
125
140
31
135
145
50
140
7001-8000
32
66
120
135
18
66
120
125
29
66
125
135
46
130
8001-9000
30
62
115
125
17
62
80
110
115
27
62
115
125
43
120
9001-10000
27
57
105
115
15
57
75
100
105
24
57
100
115
39
115
