Newest wrinkle, and I’m debating even bringing to the the contractor’s attention, is the only ( that down need to run 25’ of rectangular metal duct hanging down and is. It a bedroom) location to add a basement air return is 6-8’ from the basement fireplace and insert…….. just occurred to me today. Sucking big cold air off the basement floor seems like a win year round to me. Wonder if contractor will even notice.