Abstract: A valve is provided that controls the type of air reaching an air conditioning blower. For example, in one position of the valve, returned, air conditioned air is continually recirculated to the blower without the addition of any fresh air. In another position of the valve the recirculated air is prevented from reaching the blower and only fresh air can flow to the air conditioner blower. The valve can also be located in an infinite number of positions wherein various mixtures of fresh and recirculated air are directed to the air conditioning blower. The valve is positioned by a motor which is in turn controlled by a sensor. The valve mechanism is mounted in a housing which may be included as a part of an original air conditioning system or may be attached to an existing system as a retrofit.

Abstract: A plenum unit (10) for adapting roof construction for a prior rooftop air conditioning unit for use with a new air conditioning unit (12) is disclosed. A plenum (20) mounts on curbing (14) of the prior air conditioning unit. A partition (26) separates a supply chamber (22) from a return chamber (24), and an adaptor plate (28) is affixed to the plenum for mating the plenum unit with the new air conditioner unit. In one arrangement, the partition has a fixed portion and a movable portion to adjust for different size adaptor plate openings. Adaptor plates are interchangeable so that the plenum can be used with different types and sizes of new air conditioning units. In one arrangement, the ratio of intake air can be adjusted between return air from the return duct opening and fresh from the outside.

Abstract: A control system (12) for environmental units (10) such as air conditioners or heaters is disclosed.A control panel (14) accommodates a control module (16) associated with each unit. First and second temperature reference circuits (58 and 60) are located in each module for setting first and second reference temperatures. A circuit (64) responsive to a clock (62) selects the first reference temperature during a first predetermined time period and the second reference temperature during a second predetermined time period. Each unit is thermostatically controlled according to the selected reference temperature.