The Unique Double-wall Zero Clearance models benefit from three.twenty five” of a novel increased density ceramic fiber insulation amongst the internal liner and outer jacket. These Zero Clearance versions also are a two-hour fire-rated-resistant enclosure/duct assembly.   Plan cleaning and simple accessibility for grease filters are emphasized in NFPA 96. https://commercial-kitchen-extrac91123.vidublog.com/35797529/commercial-kitchen-extract-systems-for-dummies