Abstract: A window air handler mounted to a window admits a supply of air from inside the building at the top of the window and blows that air downwardly and onto the inner surface of the window. A leg depends downwardly from an air inlet, to air outlets which express the air across the width of the window. The air can be ambient, or heated. The so-expressed air warms the glass enough to avoid condensation on the glass, or to remove and absorb condensation which has already formed on the glass. The air handler can comprise a single leg extending down along one side of the window or two legs extending down along opposing sides of the window. Air inlets are proximate the tops of the legs, and air outlets are below the inlets.

Abstract: An air handler draws air from inside a building, optionally from a building space heating system, and expresses that air such that the air travels along the inside surface of a window glazing unit which is susceptible to condensation. The air can be expressed at ambient temperature or with a modest amount of supplemental heat. As the air is expressed onto the window, a convection curtain of relatively warmer air passes adjacent the inside surface of the glass, warming the glass enough that condensation does not form on the glass. The system can be controlled using a sensor, optionally controlled by a computer or other controller, which controls the air flow according to needs sensed at the window. Such computer can be used to provide individualized control of condensation on each of multiple windows. A blower may be used to achieve increased control of rate and persistence of air flow.