Bosch 940 ES Installation And Operating Instructions Manual page 19

For this example, the maximum allowable combustion air pipe
length is 22,25 feet.
Calculation example for 4" venting:
Exhaust
System used
Number of 90° elbows needed:
Number of 45° elbows needed:
Table 15
Calculation of example
Max. length
90° elbow reduction
sub-total =
45° elbow reduction
Total =
Table 16
For this example, the maximum allowable exhaust pipe length is
57,25 feet.
Combustion air
System used
Number of 90° elbows needed:
Number of 45° elbows needed:
Table 17
Calculation of example
Max. length
90° elbow reduction
sub-total =
45° elbow reduction
Total =
Table 18
For this example, the maximum allowable combustion air pipe
length is 58,5 feet.
940 ES – 6 720 644 930 (2019/09)
Twin pipe
2
2
61,25'
- 2,5'
58,75'
- 1,5'
57,25'
Twin pipe
1
2
61,25'
- 1,25'
60'
- 1,5'
58,5'
Installation instructions
19