Additional duct lengths (4" (100 mm) rigid pipe only)
Type of bend Radius Additional duct length
inches cm ft cm
Flexible metal duct
–
3’ 3" (1 m) straight
–
45° angle
–
90° angle
10"
10"
25
25
5’ 11"
4’ 11"
8’ 2"
180
150
250
Smooth metal duct
–
3’ 3" (1 m) straight
–
45° angle
– 90° angle
10"
10"
25
25
3’ 3"
1’ 11"
2’ 7"
100
60
80
Elbow 90° sharp
7’ 6" 230
Concertina bend
– 90° angle 8" 20 2’ 4" 70
Wall vent or window vent
–
with louvers
–
with flap
–
with weather hood
12’ 5"
4’ 11"
19’ 8"
380
150
600
Ducting
45