What is the minimum size for a kitchen range hood duct?
The minimum allowed duct size is 3¼" x 10", or 6" diameter for round ducts. Never use a plastic duct or one that is smaller than the size specified for the hood as this will directly affect the hood’s performance.
High performance hoods require larger, up to 10" diameter ducts. Refer to your hood specifications before making your choice. The duct diameter directly affects the hood’s performance.
If you modify or change your range hood, never use a duct smaller than the specified size.