Correct Installation of a Downdraft Ventilation

What is the Length of the Vent System?

• To provide efficient performance, the length of the vent system and the number of elbows should be kept to a minimum. 
• The maximum equivalent length of the vent system is 60 ft (18.3 m). For specific information, refer to your appliance's installation instructions.
• For best performance at altitudes above 4,500 ft (1372 m), reduce the recommended vent run by 20%.

Was the Correct Vent Material Used?

• Use a 26-gauge minimum galvanized vent or a 25-gauge minimum aluminum metal vent.
• Poor-quality pipe fittings can reduce airflow.
• A flexible metal vent is not recommended. 
• Metal ducts may be reduced to 30-gauge galvanized steel or 26-gauge aluminized steel if allowed by local codes. This reduction is based on information in the International Residential Codes Section M1601.1 (2006 edition).

NOTE: Local codes may require a heavier gauge material.

How Many Elbows Were Used?  

• Use no more than three 90° elbows.
• Do not install two elbows together. If more than one elbow is used, ensure a minimum of 18" (45.7 cm) of straight vent between them. Elbows too close together can cause excess turbulence that reduces airflow.
• If an elbow is used, install it as far away as possible from the hood’s vent motor exhaust opening.
• Do not use a 5" (12.7 cm) elbow in a 6" (15.2 cm) or 3¼" x 10" (8.3 cm x 25.4 cm) system.

Other Recommendations:

• Do not reduce to a 5" (12.7 cm) system after using 6" (15.2 cm) or 3¼" x 10" (8.3 cm x 25.4 cm) fittings.
• Avoid forming handmade crimps. Handmade crimps may restrict airflow.
• Use a vent cap for proper performance. If an alternate wall or roof cap is used, be certain the cap size is not reduced and that it has a back draft damper.
• Use vent clamps to seal all joints in the vent system.
• Use caulking to seal the exterior wall or roof opening around the cap.

Watch the video below for instructions on the installation of the UXD8630DYS Model downdraft vent: