Our bathroom exhaust fan died. It is vented out our roof with 3 " rigid ducting that comes out the top of the fan, not the side of the fan, and then makes a diagonal up to my roof. I bought this expensive quiet Panasonic fan, model FV11VF2, because it was supposed to be quiet and because it is made for 4" ducting but allows you to adapt it to 3" ducting. I forgot to check how this fancy fan ducts, however! I ducts out the side, not the top like my old one. What should we do?