Patent ID: 7819729

Claim:
In an air curtain doorway for forming an air curtain across a doorway between a relatively low temperature area and a relatively high temperature area, comprising duct work including a supply air duct at a first side of the doorway, said supply air duct having a supply air outlet aperture extending substantially the height of the first side, a return air duct at a second side of the doorway opposite from the first side and having a return air inlet aperture extending substantially the height of the second side, an intermediate air duct extending between the supply and return air ducts, and an air mover for moving an air stream through the duct work from the return air inlet aperture to the supply air outlet aperture, and out of the ductwork through the supply air outlet aperture so as to form an air curtain flowing from the supply air outlet aperture toward the return air inlet aperture, and to draw air into the ductwork through the return air inlet aperture, the improvement wherein: the return air duct has a collector chamber upstream of the return air inlet aperture, and wherein the return air inlet aperture is adjustable in area.