Patent ID: 9488400
Filing Date: 2016-11-08
CPC Classification: F25B

Claim Text:
1. A control system for a heating, ventilation, and air conditioning (HVAC) system, the control system comprising: a control assembly configured to operationally connect to an HVAC compressor assembly of an HVAC system for controlling the environment in an enclosed space; wherein the control assembly comprises a controller configured to control operation of a first compressor assembly and a second compressor assembly of the HVAC compressor assembly; wherein the HVAC compressor assembly is configured for operation by the controller to deliver a load capacity in one or more demand stages, wherein the controller operates the HVAC compressor assembly in at least a lower demand stage and a higher demand stage, wherein the HVAC compressor assembly delivers a larger capacity at the higher demand stage than at the lower demand stage; wherein the HVAC compressor assembly is configured for operation by the control assembly in one or more modes of operation based on an ambient temperature outside the enclosed space; wherein the first compressor assembly comprises a first tandem compressor assembly having a first compressor and a second compressor operationally connected for tandem operation as part of a first circuit having first heat transfer devices; wherein the second compressor assembly comprises at least a third compressor comprising a part of a second circuit having second heat transfer devices separated from the first heat transfer devices; wherein, in a first mode of operation, the controller is configured to operate the first compressor in an ON-state and the second compressor in an OFF-state during the lower demand stage; wherein, in response to an increase in load demand on the HVAC compressor assembly from the lower demand stage to the higher demand stage, the controller is configured to operate the first compressor in an OFF-state and the second compressor in an OFF-state to keep the first compressor and the second compressor idle for a first time period, and wherein the first time period allows lubricant levels to equalize between the first compressor and the second compressor; wherein during the first time period, the controller operates the third compressor in an ON-state to utilize the heat transfer capacity of the second heat transfer devices on the second circuit; and following expiration of the first time period, the first compressor and the second compressor are operated in an ON-state in the higher demand stage to meet the increased load demand.