This Modular Mixing Box has been designed so that there is easy access to either side of the housing. Over-sized doors offer plenty of room through which to clean and maintain dampers, linkage and actuators. The mixing box is designed to reduce energy cost by recirculating tempered air. The tempered air is mixed with fresh air, using the controls listed below. Building static pressure control allows the dampers to be adjusted to an infinite number of position, maintaining building static pressure. Manual potentiometers allow individuals to set the damper actuator to an infinite number of positions. Electric 2-position control is used to open or close the damper.