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L110 1015
Ducting Do’s and Don’ts
YES
NO
Smooth Duct
Smooth Gradual Turn
Proper Combining
of Two Ducts
Flexible Duct
Sharp Angled Turns
Improper Combining
of Two Ducts
General Requirements
•
Observe local codes regarding special duct requirements and placement of duct against combustibles.
• Using Vent-A-Hood transitions (back page) will ensure proper efficiency.
• Using Vent-A-Hood roof jacks or wall louvers (back page) will ensure proper efficiency.
•
Where possible, seal joints with duct tape.
•
The hood must be ducted to the outdoors without restrictions.
Blower Requirements
•
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).
Blower
Combined Duct Dize
Sq. Inch Area
Vent-A-Hood Transition
Single (B100)
6" round or equivalent
28 sq. in.
N/A
Dual (B200)
8" round or equivalent
50 sq. in.
N/A
Single and Dual (B100 & B200)
10" round or equivalent
79 sq. in.
VP562 (Optional)
Two Duals (Two B200s)
12" round or equivalent
113 sq. in.
VP563 (Optional)
Ducting Requirements
•
NEVER reduce the duct size.
• 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.
•
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.
Termination Requirements
• Airflow must not be restricted at the end of the duct run.
•
A wall louver or roof jack is required for each duct run.
• Every wall louver or roof jack must include a gravity damper to prevent back drafts.
•
Do not use screen wire or spring-loaded doors on wall louvers or roof jacks.
• Do not terminate venting into an attic or chimney.
