8
Pre-Installation (continued)
Follow these guidelines when installing duct work:
- Your venting system must vent to the outdoors either horizontally through the back wall (13) or vertically through the
roof (14) (refer to Fig . 4/Fig . 5) .
- Use round metal duct work with a uniform diameter of 6 in . (152 mm) . The total duct run in the venting system should
be not more than 10.7 m (35 ft).
- Calculate the total effective length of the duct work by adding the equivalent lengths in the table shown (Fig . 5) . For
each fitting used add the length of the equivalent straight duct used in the system.
- Fasten all connections between pieces of duct with sheet metal screws and tape all joints with certified duct tape.
- If you must turn the path of the duct work using elbows, keep the number of elbows to a minimum for effective
performance and use no more than three 90° elbows. Ensure that there is a minimum of 18 in. (458 mm) of straight vent
between each elbow. Elbow as far away from the range hood’s exhaust opening as possible.
- Cap the exterior of the duct with a wall cap (15) or roof cap (16). Never use 4 in. (102 mm) laundry-type wall caps. Use
caulking to seal exterior wall or roof opening around the cap.
- The venting system must have a damper . If the roof or wall cap has a damper, do not use the damper supplied with the
range hood .
Equivalent Length Chart
Type of duct
Length added
90° Elbow
5 ft (1 .52 m)
90° Flat elbow
12 ft (3 .66 m)
2 x 90° Elbow
10 ft (3.05 m)
9 ft (2.74 m) Straight duct
9 ft (2.74 m)
Wall cap
0 ft (0 m)
Fig . 5
