Installation instructions
RTG 199 HE – 6 720 811 617 (2016/01)
13
Combustion air
Calculation example for 4" PP, PVC, CPVC, or ABS venting:
Exhaust
Combustion air
Calculation example for 2" PVC venting:
Exhaust
Combustion air
For this example, the maximum allowable exhaust pipe
length is
13 feet
.
System used
Concentric
Number of 90° elbows needed:
2
Number of 45° elbows needed:
1
Table 14
Calculation of example
Max. length
23’
90° elbow reduction
- 10’
sub-total =
13’
45° elbow reduction
- 2.5’
Total =
11.5’
Table 15
For this example, the maximum allowable combustion
air pipe length is
11.5 feet
.
System used
Twin pipe
Number of 90° elbows needed:
1
Number of 45° elbows needed:
2
Table 16
Calculation of example
Max. length
63’
90° elbow reduction
- 5’
sub-total =
58’
45° elbow reduction
- 5’
Total =
53’
Table 17
For this example, the maximum allowable exhaust pipe
length is
53 feet
.
System used
Twin pipe
Number of 90° elbows needed:
2
Number of 45° elbows needed:
2
Table 18
Calculation of example
Max. length
63’
90° elbow reduction
- 10’
sub-total =
53’
45° elbow reduction
- 5’
Total =
48’
Table 19
For this example, the maximum allowable combustion
air pipe length is
48 feet
.
System used
Twin pipe
Number of 90° elbows needed:
1
Number of 45° elbows needed:
0
Table 20
Calculation of example
Max. length
9.5’
90° elbow reduction
- 5’
sub-total =
4.5’
45° elbow reduction
- 0’
Total =
4.5’
Table 21
For this example, the maximum allowable exhaust pipe
length is
4.5 feet
.
System used
Twin pipe
Number of 90° elbows needed:
0
Number of 45° elbows needed:
2
Table 22
Calculation of example
Max. length
9.5’
90° elbow reduction
- 0’
sub-total =
9.5’
45° elbow reduction
- 5’
Total =
4.5’
Table 23
For this example, the maximum allowable combustion
air pipe length is
4.5 feet
.