Abstract: Embodiments of the disclosure describe a method for controlling setback of a heating, ventilation, and air conditioning (HVAC) system comprising a first HVAC unit and a second HVAC unit. The method is performed by a setback control system. The method comprises monitoring an interior temperature and an exterior temperature of a target area associated with the HVAC system. The method comprises determining one or more operating parameters associated with the first HVAC unit of the HVAC system and determining a recovery time based on the operating parameters. The recovery time is a time required to recover interior temperature value from a setback temperature setpoint value to a normal temperature setpoint value by the first HVAC unit. The method comprises triggering a setback recovery based on the determined recovery time and a remaining time in a setback period associated with the setback of the HVAC system.

Abstract: A system for controlling operation of a heat pump configured with an electric heater. The system comprises an occupancy sensor positioned in an area of interest (AOI) and is operable to detect presence/absence of occupants within the AOI. The system supplies air within the AOI while flowing the air through the heat pump and the electric heater. The system comprises a controller that is configured to receive data pertaining to a first predefined temperature for the air to be supplied to the AOI, monitor real-time temperature of the air being supplied to the AOI, detect, using the occupancy sensor, presence of the occupants within the AOI, and operate, upon detecting the presence of the one or more occupants within the AOI, the heat pump and/or the electric heater to adjust the temperature of the air being supplied to the AOI to the first predefined temperature.

Abstract: A method of performing a defrost operation in a heating, ventilation and air conditioning (HVAC) system having a first heat exchanger and a second heat exchanger, the method including determining that the defrost operation is needed; determining a capacity for the defrost operation in response to one or more prior defrost operations; beginning the defrost operation at the determined capacity; monitoring a defrost parameter; determining if the defrost parameter indicates a need for increased capacity; and increasing the capacity of the defrost operation when the defrost parameter indicates the need for increased capacity.

Abstract: A method of operating a heat pump system comprising: operating the heat pump system in a demand operation heating mode, wherein the demand operation heating mode comprises controlling an opening amount of an expansion valve based on a superheat difference between a compressor inlet superheat value and a target compressor inlet superheat value, and controlling a flowrate of the refrigerant through a compressor based on a thermal demand difference between a thermal output of the indoor heat exchanger and a customer thermal demand; monitoring with the one or more controllers a parameter of the refrigerant cycle indicative of a charge imbalance condition; and transitioning operation with the one or more controllers to a charge compensation mode when the parameter satisfies a first threshold condition, wherein the charge compensation mode comprises performing with the one or more controllers a charge imbalance mitigation strategy.

Abstract: A method for determining when to initiate a defrost mode of a heat pump includes monitoring a heating capacity of a heat exchanger of the heat pump during operation of the heat pump in a heating mode, initiating the defrost mode when the heating capacity of the heat exchanger is less than or equal to a reduced defrost threshold when a capacity demand of the heat exchanger is less than a maximum capacity demand, and initiating the defrost mode when the heating capacity of the heat exchanger is less than or equal to a maximum defrost threshold when the capacity demand of the heat exchanger is equal to the maximum capacity demand.

Abstract: A method for controlling the temperature of a compressor having a motor including a rotor and a stator, and a control assembly operably coupled to the compressor, the method comprising the steps of: applying an initial current to the compressor motor; measuring a voltage across the compressor motor and determining a resistance of the compressor motor based on the initial current and a measured voltage; determining whether the determined resistance is less than or equal to a desired resistance; applying a secondary current to the compressor motor if the determined resistance is less than or equal to the desired resistance.

Abstract: A high pressure threshold detection circuit (100) is provided. The high pressure threshold detection circuit includes a pressure transducer (110) for measuring a pressure of a medium at an outlet (104) of a compressor (102). The high pressure threshold detection circuit (100) includes a controller (120). The controller (120) includes a comparator (123) and a switch (125). The comparator (123) and the switch (125) are electrically coupled. The switch (125) is electrically coupled to an enable circuit (131). The pressure transducer (110) is electrically coupled to the comparator (123) to provide a signal to the comparator (123) based on the pressure measured at the outlet (104). The comparator (123) outputs a control signal (111) to the switch (125) when the signal (111) is equal to or greater than a reference value (126). The switch (125) opens the enable circuit (131) to disable compression of the medium by the compressor (102) in response to the control signal (111).

Abstract: A cooling system includes a compressor operable to compress refrigerant, an accumulator upstream from the compressor. The accumulator is operable to collect liquid from the refrigerant. A sensor is located upstream from the accumulator. The sensor is operable to detect information including a temperature and a pressure of the refrigerant. The controller is in communication with the sensor. The controller is operable to determine a rate of accumulation of liquid in the accumulator based on the information from the sensor. A method of operating a cooling system is also disclosed.

Abstract: A method for determining when to initiate a defrost mode of a heat pump includes monitoring a heating capacity of an evaporator of the heat pump during operation of the heat pump in a heating mode, determining a threshold associated with the heating capacity, and initiating a defrost mode when the heating capacity of the evaporator is less than or equal to the threshold.

Abstract: A method of heating a component within a heating, ventilation and air conditioning (HVAC) system is provided. The method includes maintaining a non-heating condition of the HVAC system component when the HVAC system component is in a non-operational state. The method also includes determining when the HVAC system component will switch from the non-operational state to an operational state, the determination based on a threshold parameter being met. The method further includes operating a heating device from the non-heating condition to a heating condition to heat the HVAC system component from a temperature to a target temperature suitable for the operational state of the HVAC system component.

Abstract: A method of operating a vapor compression system configured for environmentally conditioning a space comprising: providing a compressor of the vapor compression system with a variable speed drive, operating the compressor at a first speed in response to a start command, determining a demand speed of the compressor based at least in part on a user selected target value for an environmental condition within the space, determining a maximum allowable compressor speed of the compressor based at least in part on a condition of a parameter of the vapor compression system, reducing the speed of the compressor from the first speed to a second speed, maintaining the speed of the compressor below the first speed, and operating the compressor at the demand speed once a startup condition is satisfied.

Abstract: A cooling system includes a compressor operable to compress refrigerant, an accumulator upstream from the compressor. The accumulator is operable to collect liquid from the refrigerant. A sensor is located upstream from the accumulator. The sensor is operable to detect information including a temperature and a pressure of the refrigerant. The controller is in communication with the sensor. The controller is operable to determine a rate of accumulation of liquid in the accumulator based on the information from the sensor. A method of operating a cooling system is also disclosed.

Abstract: A method of operating a heating, ventilation, and air conditioning (HVAC) system includes monitoring a parameter of the HVAC system associated with a temperature of a refrigerant at a heat exchanger, determining if the HVAC system is in an operating condition associated with frost accumulation at the heat exchanger, and adjusting a flow rate of an airflow across the heat exchanger in response to determining that the HVAC system is in the operating condition associated with frost accumulation at the heat exchanger.

Abstract: An illustrative example refrigerant system includes a compressor configured to pressurize a refrigerant fluid. The compressor includes a sump portion. A heater is situated to heat at least the sump portion. A controller is configured to selectively operate the heater to apply heat to at least the sump portion while the compressor is off to establish and maintain a superheat condition in the compressor.

Abstract: A method of operating a heat pump system comprising: operating the heat pump system in a demand operation heating mode, wherein the demand operation heating mode comprises controlling an opening amount of an expansion valve based on a superheat difference between a compressor inlet superheat value and a target compressor inlet superheat value, and controlling a flowrate of the refrigerant through a compressor based on a thermal demand difference between a thermal output of the indoor heat exchanger and a customer thermal demand; monitoring with the one or more controllers a parameter of the refrigerant cycle indicative of a charge imbalance condition; and transitioning operation with the one or more controllers to a charge compensation mode when the parameter satisfies a first threshold condition, wherein the charge compensation mode comprises performing with the one or more controllers a charge imbalance mitigation strategy.

Abstract: A method of performing a defrost operation in a heating, ventilation and air conditioning (HVAC) system having a first heat exchanger and a second heat exchanger, the method including determining that the defrost operation is needed; determining a capacity for the defrost operation in response to one or more prior defrost operations; beginning the defrost operation at the determined capacity; monitoring a defrost parameter; determining if the defrost parameter indicates a need for increased capacity; and increasing the capacity of the defrost operation when the defrost parameter indicates the need for increased capacity.

Abstract: A refrigerant system includes a compressor configured to pressurize a refrigerant fluid. The compressor includes a sump portion. A heater is situated to heat at least the sump portion. A controller is configured to selectively operate the heater to apply heat to at least the sump portion while the compressor is off and continue operating the heater when the compressor turns on until a temperature of the compressor or a temperature of fluid discharged from the compressor satisfies at least one criterion.

Abstract: In a method for operating a compressor (22) having an inlet (26) and an outlet (28), the method includes: running the compressor to compress a fluid; shutting down (422) the compressor; determining (420) a condition-dependent threshold restart pressure difference (threshold) across the compressor; relieving the pressure difference to reach the threshold; and, after the threshold is reached, restarting (434) the compressor.

Abstract: A method for controlling the temperature of a compressor having a motor including a rotor and a stator, and a control assembly operably coupled to the compressor, the method comprising the steps of: applying an initial current to the compressor motor; measuring a voltage across the compressor motor and determining a resistance of the compressor motor based on the initial current and a measured voltage; determining whether the determined resistance is less than or equal to a desired resistance; applying a secondary current to the compressor motor if the determined resistance is less than or equal to the desired resistance.

Abstract: A method of heating a component within a heating, ventilation and air conditioning (HVAC) system is provided. The method includes maintaining a non-heating condition of the HVAC system component when the HVAC system component is in a non-operational state. The method also includes determining when the HVAC system component will switch from the non-operational state to an operational state, the determination based on a threshold parameter being met. The method further includes operating a heating device from the non-heating condition to a heating condition to heat the HVAC system component from a temperature to a target temperature suitable for the operational state of the HVAC system component.