Wall Cap Type
Number of 90° Elbows
Maximum length of 10 cm diameter rigid metal duct
Recommended
0
19.8 m
1
16.8 m
2
14.3 m
3
11.0 m
4
8.5 m
Use for only short run installations
12.5 m
9.1 m
6.7 m
Deduct 1.8 m for each additional elbow. Do not use more than four 90° elbows.