15
Installation instructions
Maximum length of exhaust duct
Preferred 4” Hoods
When you have a 4” (100 mm) Hood
Maximum length of 4” diameter metal duct.
Number of 90˚
elbows/bends
Rigid
Thick Wall Flexible Metal
(fully extended)
0
64 ft
19.5 m
36 ft
10.9 m
1
54 ft
16.5 m
31 ft
9.4 m
2
44 ft
13.4 m
27 ft
8.2 m
3
35 ft
10.6 m
25 ft
7.6 m
4
27 ft
8.2 m
23 ft
7.0 m
Acceptable 2 ½” Hood
When you have a 2 ½” (60 mm) Hood
Maximum length of 4” diameter metal duct.
Number of 90˚
elbows/bends
Rigid
Thick Wall Flexible Metal
(fully extended)
0
58 ft
17.6 m
28 ft
8.5 m
1
48 ft
14.6 m
23 ft
7.0 m
2
38 ft
11.5 m
19 ft
5.7 m
3
29 ft
8.8 m
17 ft
5.1 m
4
21 ft
6.4 m
15 ft
4.5 m
For exhaust systems not covered by the exhaust duct length charts (such as multiple unit
hook-ups, plenums, and power-assist fans), call our Customer Care Center:
TOLL FREE 1 888 9 FNP USA (1 888 9 367 872).
EN