My exhaust fan system in the studio - notes below

Outside - door open

Inside - door open

Inside - door closed

The fan door has 2 ropes that allow for opening and closing. One attaches to the outside of the door and goes through a hole in the wall below the door opening. This one closes the door when open. To open the door another rope goes from the outside of the door to a pipe that goes through the wall above the door. If you pull on it the door opens. Both can be hitched to a cleat inside the studio. You can see these ropes plainly in the top inside picture.