Grease duct is either routed through a fireplace rated shaft enclosure or wrapped using an accepted fire insulating blanket that allows for zero clearances, such as that created by 3M. Assure ducting is the correct dimensions - if it is much too compact, it can limit airflow, and When the https://johnathanbshwk.ageeksblog.com/35598643/not-known-factual-statements-about-commercial-kitchen-extract-systems