Great info about vent in questions. This hood measures 21" deep from the front of the mantel to the wall. In addition to the depth, you also need to consider the height off of the cook surface and the side-to-side space to the adjoining wall cabinets. In this picture, the bottom of the mantel is 30" above the cook surface, and the width is 42". We use the Best PK22 insert with our own custom liner. Our rangetop cabinet is 24" deep, and was pulled 2" off the wall.
KITCHEN – Brad Sullivan of Sullivan Building & Design Group shares the details of this custom wood hood: "The fan itself is an insert by Broan with a roof-mounted remote blower. The enclosure was custom built with old beadboard paneling and antique wood beams."