Abstract: This invention relates to a refrigeration system having at least two compressors connected in parallel to the refrigeration system suction and discharge lines. Each compressor is adapted to operate singly or in combination in accordance with load requirements. More particularly, this invention relates to a valving arrangement associated with each compressor for preventing refrigerant from condensing in the discharge opening of the idle compressor of such a multiple compressor refrigeration system, and a refrigerant bleed arrangement associated with each compressor which directs refrigerant when present in the discharge of an idled compressor to the system suction line.

Abstract: Microprocessor controlled apparatus is provided for automatically diagnosing faults in a heat pump system. Temperature sensors located at strategic points in the system are read periodically in accordance with a preprogrammed diagnostic routine. Temperature measurements preferably representing comparison of two temperature readings that produce temperature differentials outside pre-established tolerance limits are stored with a fault identification representative of the corresponding fault measurement. A service technician can read the fault data from storage by activation of control means for that purpose whereby the nature of the causative fault or faults can readily be determined.

Abstract: A microprocessor based control for a heat pump system providing at least two setback temperature settings individually selected by the system user to be effective during different time periods of the day, also individually selectable by the user. In the event of conflicting setback temperature settings during an overlap in the selected time periods, the microprocessor is programmed to implement the setback temperature that provides the most energy efficient operation of the system. Additionally, the microprocessor automatically assures that any setback temperature settings are at least a minimum temperature differential away from the normal temperature setting in the more energy efficient direction. This override provision is effective whether the invalid setback temperature settings are initially inserted by the user or are the result of a subsequent change in the normal temperature setting.

Abstract: A muffler for attenuating the sound of the hot refrigerant gas discharged from a hermetic refrigeration compressor and for transferring heat from the hot discharged refrigerant gas to a water tube arranged in heat exchange relationship with the muffler. The water tube is adapted to be connected to a water heater tank in a manner that recirculates water from the tank through the water tube in a closed circuit.