For Best Performance:
■ Use |
aluminum metal vent. Poor quality pipe fittings can reduce |
airflow. Flexible metal vent is not recommended. |
NOTE: Local codes may require a heavier gauge material. |
■ Metal duct may be reduced to |
reduction is based on information in the International |
Residential Codes Section M1601.1 (2006 edition). |
■ Do not install 2 elbows together. |
■ Use no more than three 90° elbows. |
■ If an elbow is used, install it as far away as possible from the |
hood’s vent motor exhaust opening. |
■ Make sure there is a minimum of 18" (45.7 cm) of straight |
vent between the elbows if more than one elbow is used. |
■ Elbows too close together can cause excess turbulence that |
reduces airflow. |
■ Do not use a 5" (12.7 cm) elbow in a 6" (15.2 cm) or 3¹⁄₄" x 10" |
(8.3 x 25.4 cm) system. |
■ Do not reduce to a 5" (12.7 cm) system after using |
6" (15.2 cm) or 3¹⁄₄" x 10" (8.3 x 25.4 cm) fittings. |
■ Avoid forming handmade crimps. Handmade crimps may |
restrict airflow. |
Venting Methods
Common venting methods are shown for a
Option 1 - Roof Venting | Option 2 - Wall Venting |
B
B
A
A
A. Roof cap | A. 6" (15.2 cm) round wall venting |
B. 6" (15.2 cm) round roof venting | B. Wall cap |
■ Use a |
alternate wall or roof cap is used, be certain the cap size is |
not reduced and that it has a backdraft damper. |
■ Use vent clamps to seal all joints in the vent system. |
■ Use caulking to seal exterior wall or roof opening around the |
cap. |
The length of vent system and number of elbows should be kept to a minimum to provide efficient performance.
The maximum equivalent length of the vent system is 60 ft (18.3 m). For altitudes above 4,500 ft (1272 m), reduce recommended vent run by 20% for best performance.
Cold Weather Installations
Option 3 - Venting Between
Floor Joist
A | B |
Option 4 - Venting behind
Cabinet Kick Plate
AB
An additional backdraft damper should be installed to minimize backward cold air flow and a thermal break installed to minimize conduction of outside temperatures as part of the vent system.
The damper should be on the cold air side of the thermal break.
Makeup Air
Local building codes may require the use of makeup air systems when using ventilation systems greater than specified CFM of air movement. The specified CFM varies from locale to locale.
Consult your HVAC professional for specific requirements in your area.
A. Wall cap | A. Wall cap |
B. 6" (15.2 cm) round wall venting | B. 6" (15.2 cm) round wall venting |
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