Abstract: A diffuser for positioning in an opening of a passageway having conditioned air, the diffuser including a grate assembly, a pan assembly, and a retention assembly. The grate assembly includes an upper portion and a lower portion. The upper portion contains an aperture, a plurality of slotted sections, and a flange. The lower portion includes downwardly depending sidewalls and a stop. The pan assembly includes a tray with an aperture and a plurality of upwardly depending legs. The retention assembly couples the grate assembly with the pan assembly and contains a first member that is movable from a first position to a second position for selectively engaging the stop.

Abstract: A diffuser for positioning in an opening of a passageway having conditioned air, the diffuser including a grate assembly, a pan assembly, and a retention assembly. The grate assembly includes an upper portion and a lower portion. The upper portion contains an aperture, a plurality of slotted sections, and a flange. The lower portion includes downwardly depending sidewalls and a stop. The pan assembly includes a tray with an aperture and a plurality of upwardly depending legs. The retention assembly couples the grate assembly with the pan assembly and contains a first member that is movable from a first position to a second position for selectively engaging the stop.

Abstract: A heating, ventilation, and air conditioning (HVAC) system uses unvitiated secondary return air to control the amount of a contaminant, such as carbon dioxide, in a space to maintain an improved air quality throughout the area served by the system. Preferably a terminal box controls the CO.sub.2 level in the space served by the box by selectively drawing air representative of air in other rooms to lower the CO.sub.2 level in the space being served. This reduces cost because air which is provided from other rooms within the building will require less total system heating or cooling in order to maintain the occupied space at the desired air quality.

Abstract: An air conditioning unit is provided with a high capacity filtration system for removing pollutants from supply air, typically return air which has been recirculated from the conditioned area. A filter bypass passage and suitable flow control devices are provided so that supply air, typically fresh outdoor air, may be routed around the filtration system when minimal or no filtration is required. An air quality detector samples the air quality and positions the flow control devices to effect the most cost efficient operation of the air handling unit under the given operating conditions.

Abstract: An air conditioning unit is provided with a high capacity filtration system for removing pollutants from supply air, typically return air which has been recirculated from the conditioned area. A filter bypass passage and suitable flow control devices are provided so that supply air, typically fresh outdoor air, may be routed around the filtration system when minimal or no filtration is required. An air quality detector samples the air quality and positions the flow control devices to effect the most cost efficient operation of the air handling unit under the given operating conditions.

Abstract: An air conditioning unit is provided with a high capacity filtration system for removing pollutants from supply air, typically return air which has been recirculated from the conditioned area. A filter bypass passage and suitable flow control devices are provided so that supply air, typically fresh outdoor air, may be routed around the filtration system when minimal or no filtration is required. An air quality detector samples the air quality and positions the flow control devices to effect the most cost efficient operation of the air handling unit under the given operating conditions.

Abstract: The desirable features of self powered air distribution terminals and electronic controls are combined by providing an interface between the electronic controls and one or more self powered terminal units in an air distribution system. The electronic controls monitor temperatures and other conditions and provide electric signals each having a voltage which represents the difference between the sensed condition and a set condition entered into the system microprocessor. The interface may be an electro-pneumatic transducer or a set of solenoid valves. The interface responds to the electric signals by applying proportional pressure signals to one or more terminal units. The flow of conditioned air into the area or areas served by the system is then adjusted to conform the actual conditions with the set conditions.