Abstract: A heat transfer circuit includes a compressor, a heat exchanger, an expander, a plurality of valves, and a working fluid. The heat exchanger including a plurality of coils and is configured to exchange heat between the working fluid and a process fluid. The working fluid flows through the first heat exchanger in a first direction by flowing through the plurality of coils in series and in a second direction by flowing through the plurality of coils in parallel. A method of operating a heat transfer circuit includes operating in a first mode and operating in a second mode. In the first mode, working fluid flows though coils of a heat exchanger in series. In a second mode, the working fluid flows through the coils of the heat exchanger in parallel.

Abstract: An HVAC unit ventilator, particularly suited for schools and hotels, includes a single damper blade driven directly by a motor to control a supply air's mixture of return air and outside air. The damper blade is selectively pivotal to a full outside air position, a full return air position, and various intermediate mixed-air positions. The damper blade has flexible edge and end seals that create little if any frictional drag as the damper blade pivots to the intermediate positions, yet the seals provide a positive, tight seal when the damper stops at either the full outside air position or the full return air position. The unit ventilator includes a filter frame that not only supports an air filter but also provides the damper blade with sealing surfaces and structural support. For rigidity, the damper blade has somewhat of a box-like structure that is bi-directionally reinforced by ribs and triangular gussets.

Abstract: An HVAC unit ventilator, particularly suited for schools and hotels, includes a single damper blade driven directly by a motor to control a supply air's mixture of return air and outside air. The damper blade is selectively pivotal to a full outside air position, a full return air position, and various intermediate mixed-air positions. The damper blade has flexible edge and end seals that create little if any frictional drag as the damper blade pivots to the intermediate positions, yet the seals provide a positive, tight seal when the damper stops at either the full outside air position or the full return air position. The unit ventilator includes a filter frame that not only supports an air filter but also provides the damper blade with sealing surfaces and structural support. For rigidity, the damper blade has somewhat of a box-like structure that is bi-directionally reinforced by ribs and triangular gussets.

Abstract: A self-contained indoor air conditioning system includes a removable chassis comprising an indoor air condensor/evaporator, an outdoor air condensor/evaporator and a compressor. The chassis can be easily removed from the housing enclosure and taken to a nearby repair station for a major overhaul. Flanges and bulkheads are provided on the chassis and interiorly of the housing to separate air flow to the indoor and outdoor blower fans which are positioned in the upper portion of the housing proximate the electric controls.