Abstract: A controller of a heating, ventilation, and air conditioning (HVAC) system, the controller comprising instructions that cause the controller to determine an air flowrate of an air blower of the HVAC system and calculate a threshold value based on a minimum required air flowrate. The controller further comprises instructions that cause the controller to send a notification to an operator of the HVAC system indicating that the air flowrate of the air blower is less than the threshold value in response to determining that the air flowrate of the air blower is less than the threshold value and shut down the HVAC system such that the refrigerant is no longer circulated by the componentry of the HVAC system in response to determining that the air flowrate of the air blower is less than the minimum required air flowrate.

Abstract: In an embodiment, a method of preventing evaporator coil freeze in a heating, ventilation and air conditioning (HVAC) system includes determining a reference saturated suction temperate (SST) via a sensor disposed in relation to an evaporator coil in the HVAC system, where the HVAC; system is operating in reheat dehumidification mode. The method also includes determining whether the reference SST is below a minimum SST threshold. The method also includes, responsive to a determination that the reference SST is below the minimum SST threshold, determining a decreased compressor speed. The method also includes modulating a variable-speed. compressor in the HVAC system in correspondence to the decreased compressor speed.

Abstract: A compressor system includes a first compressor and a second compressor. A suction equalization line fluidly couples the first compressor and the second compressor. A first branch suction line is fluidly coupled to the first compressor and a second branch suction line is fluidly coupled to the second compressor. A main suction line is fluidly coupled to the first branch suction line and the second branch suction line. An obstruction device is disposed in at least one of the first branch suction line and the second branch suction line. Responsive to deactivation of at least one of the first compressor and the second compressor, the obstruction device is at least partially closed thereby causing prescribed liquid levels in the first compressor and the second compressor during partial-load operation.

Abstract: A refrigerant detector testing system according to aspects of the disclosure includes a metering orifice formed in a suction line that is disposed between an evaporator coil and a compressor, a valve fluidly coupled to the metering orifice, a connecting tube fluidly coupled to the valve on a side opposite the metering orifice, a mixing device having an input orifice fluidly coupled to the connecting tube. In some embodiments, the mixing device includes an air intake disposed proximate the input orifice, a throttling portion downstream of the input orifice and the air intake, the throttling portion having a reduced cross-sectional area, and a diffuser section positioned downstream of the throttling portion, the diffuser section having an output orifice. According to aspects of the disclosure, a refrigerant detector fluidly exposed to the output orifice.

Abstract: An HVAC system includes an indoor heat-exchange coil disposed between a supply air duct and a return air duct. A damper is disposed in a re-circulation duct and is moveable between an open position and a closed position. A controller is configured to determine if the HVAC system is operating in a heating mode or an air-conditioning mode. Responsive to a determination that the HVAC system is operating in the air-conditioning mode, the controller is configured to determine if the variable-speed indoor circulation fan is operating at a minimum speed and if the relative humidity measured by the humidity sensor is above a pre-determined threshold. Responsive to a determination that the variable-speed indoor circulation fan is operating at the minimum speed and the relative humidity of the enclosed space is above the pre-determined threshold, the controller signals the damper to move to the open position.

Abstract: In an embodiment, a method of preventing evaporator coil freeze in a heating, ventilation and air conditioning (HVAC) system is performed by a controller in the HVAC system. The method includes determining a reference saturated suction temperate (SST) via a sensor disposed in relation to an evaporator coil in the HVAC system. The method also includes determining whether the reference SST is below a minimum SST threshold. The method also includes, responsive to a determination that the reference SST is below the minimum SST threshold, increasing a discharge air temperature (DAT) setpoint.

Abstract: A method of mitigating a freeze event in an HVAC system includes measuring a saturated suction temperature, receiving actual temperature value reflective of the measured saturated suction temperature, determining whether the actual temperature value is less than a first pre-determined minimum threshold temperature value, and responsive to a determination that the actual temperature value is less than the first pre-determined minimum threshold temperature value, initiating a timer to operate for a pre-determined time interval. Determining whether the actual temperature value is less than a second pre-determined minimum threshold temperature value.

Abstract: A metering device is fluidly coupled to the condenser coil. A distributor is fluidly coupled to the metering device. An evaporator coil is fluidly coupled to the distributor via a plurality of evaporator circuit lines. A re-heat coil is disposed adjacent to the evaporator coil. The re-heat coil includes a first fluid connection to the metering device via a re-heat return line and a second re-heat feed line. The re-heat coil includes a second fluid connection to the condenser coil via a connecting line and a condenser intake line. A first check valve is disposed between the connecting line and the condenser intake line. A second check valve is disposed between the re-heat return line and the second re-heat feed line.

Abstract: An HVAC system includes an evaporator, a first sensor coupled to the evaporator at a first position, and a second sensor operably coupled to the evaporator at a second position. The first sensor monitors a first temperature of the refrigerant flowing in the evaporator at the first position, which is adjacent to the evaporator inlet. The second sensor monitors a second temperature of the refrigerant flowing in the evaporator at the second position, which is downstream from the first position. The system includes a controller, which receives a first signal corresponding to the first temperature and a second signal corresponding to the second temperature. The controller determines, based on the received signals, a temperature difference between the second temperature and the first temperature. In response to determining that the temperature difference is greater than a predefined threshold value, the controller determines that a loss of charge has occurred.

Abstract: A compressor system includes at least two compressors. A suction equalizing tube fluidly couples the at least two compressors. A plumbing assembly fluidly couples to the first compressor and the second compressor. The plumbing assembly comprises an outlet to each compressor of the at least two compressors. A pressure differential between the at least two compressors is created so as to facilitate maintenance of a desired fluid level in the at least two compressors.

Abstract: An HVAC system includes an evaporator, a first sensor coupled to the evaporator at a first position, and a second sensor operably coupled to the evaporator at a second position. The first sensor monitors a first temperature of the refrigerant flowing in the evaporator at the first position, which is adjacent to the evaporator inlet. The second sensor monitors a second temperature of the refrigerant flowing in the evaporator at the second position, which is downstream from the first position. The system includes a controller, which receives a first signal corresponding to the first temperature and a second signal corresponding to the second temperature. The controller determines, based on the received signals, a temperature difference between the second temperature and the first temperature. In response to determining that the temperature difference is greater than a predefined threshold value, the controller determines that a loss of charge has occurred.

Abstract: An HVAC system includes an evaporator coil and a compressor fluidly coupled to the evaporator coil. A condenser coil is fluidly coupled to the compressor. The condenser coil includes at least one condenser circuit fluidly coupled between a discharge line and an exit manifold. A sub-cool circuit is fluidly coupled between the exit manifold and a liquid line. A first temperature sensor is disposed at an entrance to the sub-cool circuit. A second temperature sensor is disposed at an exit to the sub-cool circuit. An HVAC controller is operatively coupled to the first temperature sensor and the second temperature sensor. The HVAC controller is configured to determine a temperature difference across the sub-cool circuit.

Abstract: An HVAC system includes a blower, a motor drive, and a controller. A benchmark rate of the flow of air provided by the blower and a corresponding benchmark power output of the motor drive associated with operation of the blower at a test condition are received. The controller determines a first motor drive frequency at which the motor drive is operating. Based on the benchmark rate and a comparison of the first motor drive frequency to the predefined motor drive frequency, a first rate of the flow of air provided by the blower is determined. At a later time, a current power output of the motor drive is determined during operation of the blower at the test condition. Based on a comparison of the current benchmark power output to the benchmark power output, an updated benchmark rate of the flow of air provided by the blower is determined.

Abstract: An HVAC system includes a blower. The blower includes a driven pulley and a motor with a driver pulley. A motor drive supplies electrical power to the motor. A controller receives a benchmark rate of the flow of air provided by the blower and a corresponding benchmark output current of the motor drive. A benchmark input power corresponding to the benchmark output current is determined based on a predetermined relationship between input power and output current for the motor drive. A ratio of the benchmark rate of the flow of air provided by the blower to the benchmark input power is determined. The controller determines a pulley ratio for the blower based on this ratio.

Abstract: An HVAC system includes a blower. The blower includes a driven pulley and a motor with a driver pulley. A motor drive supplies electrical power to the motor. A controller receives a benchmark rate of the flow of air provided by the blower and a corresponding benchmark output current of the motor drive associated with operation of the blower at a test condition. A benchmark input power corresponding to the benchmark output current is determined based on a predetermined relationship between input power and output current for the motor drive. A ratio of the benchmark rate of the flow of air provided by the blower to the benchmark input power is determined. The controller determines a pulley ratio for the blower based on this ratio. The pulley ratio corresponds to the ratio of a diameter of the driven pulley to a diameter of the driver pulley of the blower.

Abstract: An apparatus that includes a supply duct and a return duct fluidly coupled to the supply duct. A first evaporator is disposed between the supply duct and the return duct. A second evaporator is disposed between the supply duct and the return duct. A fresh-air intake is disposed between the supply duct and the return duct upstream of the first evaporator and the second evaporator. A first plurality of dampers are disposed upstream of the first evaporator. A second plurality of dampers are disposed upstream of the second evaporator. A divider panel is disposed between the first evaporator and the second evaporator. The divider panel directs air egressing the first plurality of dampers across the first evaporator and air egressing the second plurality of dampers across the second evaporator.

Abstract: An HVAC system includes an evaporator coil and a compressor fluidly coupled to the evaporator coil. A condenser coil is fluidly coupled to the compressor. The condenser coil includes at least one condenser circuit fluidly coupled between a discharge line and an exit manifold. A sub-cool circuit is fluidly coupled between the exit manifold and a liquid line. A first temperature sensor is disposed at an entrance to the sub-cool circuit. A second temperature sensor is disposed at an exit to the sub-cool circuit. An HVAC controller is operatively coupled to the first temperature sensor and the second temperature sensor. The HVAC controller is configured to determine a temperature difference across the sub-cool circuit.

Abstract: An HVAC system includes a compressor, condenser, and evaporator. A sensor measures a value associated with the refrigerant in the condenser or the evaporator, and a controller is communicatively coupled to the compressor and the sensor. The controller determines, based on an operational history the compressor, that pre-requisite criteria are satisfied for entering a sensor validation mode. After determining the pre-requisite criteria are satisfied, an initial sensor measurement value is determined. Following determining the initial sensor measurement value, the compressor is operated according to a sensor-validation mode. Following operating the compressor according to the sensor-validation mode for at least a minimum time, a current sensor measurement value is determined. The controller determines whether validation criteria are satisfied for the current sensor value. In response to determining that the validation criteria are satisfied, the controller determines that the sensor is validated.

Abstract: An HVAC system includes a variable-speed compressor which compresses refrigerant flowing through the HVAC system, a blower which provides a flow of air through the HVAC system at a controllable flow rate, and a controller communicatively coupled to the variable-speed compressor and the blower. The controller receives a demand request, which includes a command to operate the HVAC system at a predefined setpoint temperature. In response to receiving the demand request, a setpoint temperature associated with the HVAC system can be adjusted to the predefined setpoint temperature. A speed of the variable-speed compressor is decreased to a low-speed setting. Based on the decreased speed of the variable-speed compressor, an air-flow rate can be determined to provide by the blower. The controllable flow rate of the flow of air provided by the blower can be adjusted based on the determined air-flow rate.

Abstract: An HVAC system includes a variable-speed compressor which compresses refrigerant flowing through the HVAC system, a blower which provides a flow of air through the HVAC system at a controllable flow rate, and a controller communicatively coupled to the variable-speed compressor and the blower. The controller receives a demand request which includes a command to reduce power consumption by the HVAC system. In response to receiving the demand request, a speed of the variable-speed compressor is decreased and the controllable flow rate of the flow of air provided by the blower is adjusted. Accordingly, a ratio of the first flow rate to the decreased tonnage of cooling is increased to a predefined value, and a power consumption of the HVAC system is decreased by at least a predefined percentage associated with the demand request.