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JDIH 0715A
Ducting Do’s and Don’ts
YES
NO
Smooth Duct
Smooth Gradual Turn
Flexible Duct
Sharp Angled Turns
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 island dual blower unit (T200) requires 8” round duct or equivalent (50 square inches), and the
island cluster blower unit (T400) requires 12” round duct or equivalent (113 square inches).
Blower
Combined Duct Dize
Sq. Inch Area
Vent-A-Hood Transition
Island Dual (T200)
8" round or equivalent
50 sq. in.
VP565 (Included)
Island Cluster (T400)
12" round or equivalent
113 sq. in.
VP564 (Included)
Ducting Requirements
•
NEVER reduce the duct size.
• 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.
