Skuttle self adjusting fresh air controls permit your existing furnace to suck clean air from outside your home, filter it, mix it with your existing air, heat or cool it and introduce it into your home. They are simple to install and required in some municipalities. Simply cut a hole in your outside wall, install the Skuttle fresh air control and run some round ductwork to your existing return air ductwork. The built in fresh air damper will open when your furnace comes on and close when your furnace turns off. All without any wiring.