I've had this exact model for about two years. My wife and I are both smokers.  This fan is very good at exhausting inside smoke to the outside.  Also when something starts smoking on the stove and fills the house with smoke, this fan will clear the whole house in less than a minute.  Electric reversing makes three speeds available for either exhausing or bringing fresh air in directly with just the twist of a knob. At medium and high speeds it helps to crack a window on the other side of the house.  Think of it as an 'attic fan' in your window.  Our window are 5' in height and this sits in the bottom 2' and since the window sill is only 8" off the floor, the fan does not block the view at all except for the dogs.