Vent-a-Hood CWEH9 Installation Instructions Manual - Ducting Do’S and Don’Ts
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L152 0611A
Ducting Do’s and Don’ts
NEVER restrict the duct size. The single blower unit (B100) requires 6” round duct or equivalent
(28 square inches), and the dual blower unit (B200) requires 8” round duct or equivalent (50
square inches). When combining ducts together, the square inch area must reflect the total
square inch area of the ducts being combined.
Do not use flexible or corrugated duct. This type of duct will restrict airflow and reduce
performance. Only use smooth, galvanized, metal duct. Observe local codes regarding special
duct requirements and placement of duct against combustibles. Make the duct run as short and
as straight as possible with as few turns as possible. Avoid sharp-angled turns. Instead, use
smooth, gradual turns such as adjustable elbows or 45 degree angled turns. For duct runs over
20 feet, increase the duct diameter by one inch for every ten feet of duct. A 90 degree elbow
is equal to 5 feet of duct. Using Vent-A-Hood ducting products (back page) will ensure proper
efficiency. Airflow must not be restricted at the end of the duct run. Do not use screen wire
or spring-loaded doors on wall louvers or roof jacks. Do not terminate venting into an attic or
chimney. Where possible, seal joints with duct tape. The hood must be ducted to the outdoors
without restrictions.
Blower
Duct Size
Sq. Inch Area Vent-A-Hood Transition
Single (B100)
6” round or equivalent
28”
N/A
Dual (B200)
8” round or equivalent
50”
N/A
Single and Dual (B100 & B200) 10” round or equivalent
79”
N/A
Two Dual (Two B200s)
12” round or equivalent
113”
N/A
YES
NO
Smooth Duct
Smooth Gradual Turn
Proper Combining
of Two Ducts
Flexible Duct
Sharp Angled Turns
Improper Combining
of Two Ducts