F96CTN and G96CTN (Series A): Installation, Start-up, Operating, Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
40
A10497
Fig. 51 – Vent Terminations for Ventilated Combustion Air
Table 12 – Maximum Allowable Exposed Vent Lengths Insulation Table
Maximum Allowable Exposed Vent Length in Unconditioned Space - Ft.
Winter
Design
Temp
°F
Unit Size
40,000* BTUH
60,000 BTUH
Uninsulated
3/8-in.
Insulation
1/2-in.
Insulation
Uninsulated
3/8-in. Insulation
1/2-in. Insulation
Pipe Dia.
in.
1 ½
2
2 ½ 1 ½
2
2 ½ 1 ½
2
2 ½
1 ½
2
2 ½ 3
1 ½
2
2 ½
3
1 ½
2
2 ½ 3
20
20
20
20
20
50
45
20
60
50 20
30
30
25
20
75
65
60
20
85
75
65
0
10
5
5
20
25
20
20
30
25 15
15
10
10
20
40
30
25
20
45
40
30
-20
5
20
15
10
20
20
15 10
5
20
25
20
15
20
30
25
20
-40
15
10
5
15
15
10 5
20
15
15
10
20
20
15
10
3” (76 mm)
12” (305 mm)
Pipe hangar
Ventilated Combustion Air
intake termination in crawl
space
Ventilated Combustion
Air intake pipe
CRAWL SPACE
ATTIC
highest level of insulation
