Does anyone know the dimensions of the vent opening in the roof of a Vista 27PE for the fan in the kitchen area. That OEM fan has to go!!! Way too loud and hardly moves any air! Thought I read it was 14" X 14", but can't remember.... it doesn't seem that big. Unit is in storage right now so I can't measure it. Trying to get a remote control fan for my vertically challenged wife...LOL!!!