The primary literature for the hood states that a ceiling height of 7' 7" minimum is required. Not until we purchased the hood did we learn on page 11 of the owner's manual that a height of 7' 10" is required if you are using the hood to recirculate; otherwise the vents are covered on the sides. We have a 7' 8 1/2" ceiling height. This information should not be buried in the literature! Fortunately we had a machine shop who were able to cleanly cut the exterior stainless steel stack down 2 1/2" to expose the ventilation slots. Cost us more and was extremely stressful!