PG92MSA: 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.
43
Table 16 – Maximum Allowable Exposed Vent Lengths in Unconditioned Space Table - Ft.
Maximum Allowable Exposed Vent Length in Unconditioned Space (Metric)
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
Winter
Design
Temp 
°F
Unit Size
80,000 BTUH
Uninsulated  3/8-in. Insulation 1/2-in. Insulation
Pipe Dia. in. 1 ½ 2 2 ½  3 4 1 ½ 2 2 ½  3 4 1 ½ 2 2 ½  3 4
20 15 40 40 35 30 15 50 90 75 65 15 50 70 70 70
0 15 20 15 10 5 15 50 45 35 30 15 50 50 40 35
-20 15 10 5
15 35 30 20 15 15 40 30 25 15
-40 10 5
15 25 20 15 5 15 30 25 20 10
Winter 
Design 
Temp 
°F
Unit Size
100,000 BTUH
Uninsulated  3/8-in. Insulation 1/2-in. Insulation
Pipe Dia. in. 2 2 ½ 3 4 2 2 ½  3 4 2 2 ½  3 4
20 20 50 40 35 20 80 95 80 20 80 105 90
0 20 20 15 10 20 55 45 35 20 65 55 45
-20 15 10 5
20 35 30 20 20 45 35 25
-40 10 5 20 25 20 10 20 30 25 15
Winter 
Design 
Temp 
°F 
Unit Size
120,000 BTUH
140,000 BTUH
Uninsulated  3/8-in. Insulation 1/2-in. Insulation Uninsulated  3/8-in. Insulation 1/2-in. Insulation
Pipe Dia. in. 2 ½  3 4 2 ½  3 4 2 ½ 3 4 2 ½ 3 4 2 ½ 3 4 2 ½  3 4
20 10 50 40 10 75 95 10 75 105 5 55 50 5 65 105 5 65 125
0 10 20 15 10 55 45 10 65 50 5 25 15 5 65 50 5 65 60
-20 10 10
10 35 25 10 45 30 5 10 5 5 45 30 5 50 40
-40 10 5 10 25 15 10 30 20 5 5 5 30 20 5 35 25
Winter 
Design 
Temp 
°C
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. 
mm
38 51 64  38 51 64  38 51 64  38 51 64  76 38 51 64  76 38  51 64  76
-7 6.1 6.1 6.1 6.1 15.2 13.7 6.1 18.3 15.2 6.1 9.1 9.1 7.6 6.1 22.9 19.8 18.3 6.1 25.9 22.9 19.8
-18 3.0 1.5 1.5 6.1 7.6 6.1 6.1 9.1 7.6 4.6 4.6 3.0 3.0 6.1 12.2 9.1 7.6 6.1 13.7 12.2 9.1
-29 1.5
6.1 4.6 3.0 6.1 6.1 4.6 3.0 1.5 6.1 7.6 6.1 4.6 6.1 9.1 7.6 6.1
-40 4.6 3.0 1.5 4.6 4.6 3.0 1.5 6.1 4.6 4.6 3.0 6.1 6.1 4.6 3.0
Winter
Design
Temp 
°C
Unit Size
80,000 BTUH
Uninsulated  3/8-in. Insulation 1/2-in. Insulation
Pipe Dia. 
mm
38 51 64  76 102 38 51 64  76 102 38  51 64  76 102
-7 4.6 12.2 12.2 10.7 9.1 4.6 15.2 27.4 22.9 19.8 4.6 15.2 21.3 21.3 21.3
-18 4.6 6.1 4.6 3.0 1.5 4.6 15.2 13.7 10.7 9.1 4.6 15.2 15.2 12.2 10.7
 -29 4.6 3.0 1.5
4.6 10.7 9.1 6.1 4.6 4.6 12.2 9.1 7.6 4.6
-40 3.0 1.5 4.6 7.6 6.1 4.6 1.5 4.6 9.1 7.6 6.1 3.0
Winter 
Design 
Temp 
°C
Unit Size
100,000 BTUH
Uninsulated  3/8-in. Insulation 1/2-in. Insulation
Pipe Dia. 
mm
51 64  76 102 51 64  76 102 51 64  76 102
-7 6.1 15.2 12.2 10.7 6.1 24.4 28.9 24.4 6.1 24.4 32.0 27.4
-18 6.1 6.1 4.6 3.0 6.1 16.8 13.7 10.7 6.1 19.8 16.7 13.7
-29 4.6 3.0 1.5
6.1 10.7 9.1 6.1 6.1 13.7 10.7 7.6
-40 3.0 1.5
6.1 7.6 6.1 3.0 6.1 9.1 7.6 4.6