Abstract: A subcooler is provided in heat exchange relationship with the high pressure liquid refrigerant line flowing to the indoor coil, such that when a low pressure condition is sensed on the low pressure side of the system, the subcooler flashes a portion of the liquid refrigerant to the low pressure side to thereby maintain suction pressure to the compressor, while at the same time subcooling the liquid refrigerant flowing to the fan coil to thereby increase its efficiency.

Abstract: Apparatus and a method for providing failsafe supplemental heat operation of an air conditioning control are disclosed. Operating power to a microprocessor control is discontinued when the air conditioning unit is placed in a supplemental heat mode by the user. The microprocessor control is so arranged that appropriate connections are made to operate a supplemental heat source in response to a first stage heating need being sensed by the thermostat when operating power to the microprocessor control is discontinued. Under normal conditions multiple stage heating operation is provided with a supplemental heat source being operated under control of a programmed microprocessor.

Abstract: A method and apparatus for evaluting the performance of a heat exchanger are described. Water is supplied to the heat exchanger at a known mass flow rate and temperature. The water is directed to traverse a flow path of the heat exchanger. The water is then heated and redirected into another flow path of the heat exchanger in heat exchange relation with the first flow path. The temperature change of the water over a flow path is measured to determine the performance of the heat exchange. The water flow rate and incoming water temperature may be fixed to make a single discharge temperature measurement sufficient to calculate heat exchager performance.

Abstract: An apparatus and a method for controlling the capacity of a reciprocating compressor by altering the effective stroke length of the working piston of the compressor is disclosed. The working piston of the compressor has a piston opening extending through the top surface thereof. A bypass piston having a cylindrical portion sized to block the piston opening and a reduced cross-sectional portion designed to allow gas to flow through the piston opening is provided. By adjusting the position of the bypass piston the effective stroke length of the working piston may be controlled to allow modulating compressor operation.

Abstract: A flash subcooler is provided to meter a portion of the refrigerant flowing from the condenser to the evaporator to an intermediate heat exchanger to subcool refrigerant flowing from the condenser to the evaporator. This diverted refrigerant is flashed to provide subcooling and is then redirected to the compressor as is the flow of refrigerant from the evaporator. Both the refrigeration system and subassemblies for accomplishing the above are disclosed as well as methods of operation thereof.

Abstract: A flash subcooler is provided to meter a portion of the refrigerant flowing from the condenser to the evaporator to an intermediate heat exchanger to subcool refrigerant flowing from the condenser to the evaporator. This diverted refrigerant is flashed to provide subcooling and is then redirected to the compressor as is the flow of refrigerant from the evaporator. Both the refrigeration system and and subassemblies for accomplishing the above are disclosed as well as methods of operation thereof.