We followed the manufacturer's instructions about re-positioning the fan motor and installing the vent damper (easy). We constructed a duct system from the microwave to the outside of the house (challenging). We used 3.25" x 10" metal duct to start the system through the wall behind the microwave, where we added framing to reinforce a cut stud. We ran the duct up a closet wall and through its ceiling into the attic. We had to make an offset duct piece from 3.25" x 10" metal duct to clear a ceiling joist. To align parts in the attic, we transitioned to 7" round duct and back to 3.25" x 10" duct at the rectangular wall cap through the side of the house. We modified duct joints as necessary and slanted the horizontal ducts downward toward the wall cap so any condensation would run out of the wall cap rather than accumulating or dripping onto ceilings. We installed metal straps to support the ducts and secured all duct joints with sheet metal screws and metal duct tape. We may add duct insulation wrap to exposed ducts.