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 temperature (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 heating, ventilation, and air conditioning (HVAC) control device configured to receive a user input for controlling an HVAC system, to determine whether the user input indicates an energy saving occupancy setting, and to identify a first plurality of time entries that are associated with a confidence level for a predicted occupancy status that is less than a predetermined threshold value in the predicted occupancy schedule. The device is further configured to modify the predicted occupancy schedule by setting the first plurality of time entries to an away status when the user input indicates an aggressive energy saving occupancy setting. The device is further configured to modify the predicted occupancy schedule by setting the second plurality of time entries to a present status when the user input indicates a conservative energy saving occupancy setting. The device is further configured to output the modified predicted occupancy schedule.

Abstract: A method of initiating a low-energy cooling mode using a controller of an HVAC system includes measuring a temperature of ambient air proximal to a condenser coil and determining whether the temperature of the ambient air proximal the condenser coil is less than a temperature threshold. If the temperature of the ambient air is less than the temperature threshold, the HVAC system is configured to operate in a low-energy cooling mode. In the low-energy cooling mode, the controller opens a first bypass valve to allow a refrigerant to bypass a compressor and the compressor is powered off. The HVAC system is operated until a cooling demand has been met.

Abstract: A method of mitigating liquid-refrigerant migration includes comparing a requested compressor speed of a variable-speed compressor to a pre-defined threshold and, responsive to a determination that the requested compressor speed is greater than the pre-defined threshold, operating the variable-speed compressor at a first compressor speed that is less than the requested compressor speed.

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 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 controller configured to receive weather forecast information including anticipated future outdoor temperatures. Based at least in part on the weather forecast information, the controller determines that test-initiation criteria are satisfied for testing operation of the HVAC system in a test mode. In response to determining that the test-initiation criteria are satisfied, the controller determines that current weather conditions are suitable for operating the HVAC system in the test mode for a test time period. The HVAC system is operated in the test mode for the test time period.

Abstract: An occupancy tracking device configured to receive a plurality of sound samples over a predetermined time period. The device is further configured to compute an audio signature for each sound sample. The audio signature includes a numerical value that uniquely identifies characteristics of an audio signal. The device is further configured to populate entries in the voice data log for the sound samples, to identify one or more clusters based on an audio signature that is associated with the populated entries, and to determine a number of clusters that are identified. The device is further configured to determine a predicted occupancy level based on the number of clusters that are identified and to control a Heating, Ventilation, and Air Conditioning (HVAC) system based on the predicted occupancy level.

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 occupancy tracking device configured to establish a network connection with an access point and to capture wireless signal distortion information for the network connection. The device is further configured to generate statistical metadata for the wireless signal distortion information. The device is further configured to input the wireless signal distortion information and the statistical metadata for the wireless signal distortion information into a machine learning model. The machine learning model is configured to determine a predicted occupancy level based on the wireless signal distortion information and the statistical metadata for the wireless signal distortion information. The predicted occupancy level indicates a number of people that are present within with the space. The device is further configured to obtain the predicted occupancy level from the machine learning model and to control a Heating, Ventilation, and Air Conditioning (HVAC) system based on the predicted occupancy level.

Abstract: An HVAC system includes a reversing valve configured to receive refrigerant and direct the received refrigerant based on an operating mode of the HVAC system. A sensor measures a heat-exchanger temperature associated with an outdoor heat exchanger. A controller monitors an outdoor temperature and the heat-exchanger temperature and compares these temperatures. The controller determines whether the HVAC system is intended to operate in a cooling or heating mode. If the heat-exchanger temperature is less than the outdoor temperature and the HVAC system is intended to operate in the cooling mode, the controller determines that a first reversing-valve fault is detected. The first reversing-valve fault is associated with the reversing valve being in the heating configuration when the HVAC system is intended to operate in the cooling mode.

Abstract: A network of wireless remote climate sensors in a heating, ventilation, and air conditioning (HVAC) system permits the creation of personalized microclimates within an enclosed space. In addition to collecting temperature and humidity data, the wireless remote climate sensors can detect whether the enclosed space is occupied by a human. Human detection is made possible by optional cameras, microphones, and gas sensors on the wireless remote climate sensors. As the human moves throughout the enclosed space, the HVAC system is able to track the human's movement using the wireless remote climate sensors. The HVAC system may adjust airflow to different portions of the enclosed space based on the human's location. The result is an efficient use of system resources to keep users at their ideal temperature.

Abstract: An HVAC system includes a blower configured to provide a flow of air into a conditioned space. A temperature sensor measures a discharge air temperature of the flow of air provided to the conditioned space. The blower provides the flow of air at a predefined flow rate. The controller determines that the measured discharge air temperature satisfies predefined stability criteria associated with a change in the discharge air temperature during a first period of time being less than a threshold value. If the stability criteria are satisfied, a temperature offset is determined between the discharge air temperature and an indoor temperature. The temperature offset is stored in a memory and is associated with the flow rate of air provided by the blower and the outdoor temperature.

Abstract: A controller of an HVAC system is communicatively coupled to a liquid-side sensor and a shutoff switch. The controller stores measurements of a liquid-side property over an initial period of time. The controller detects that the shutoff switch is tripped at a first time stamp corresponding to an end of the initial period of time. The controller accesses the measurements of the liquid-side property. The controller determines, based on the measurements of the liquid-side property, that the liquid-side property has an increasing trend. In response to determining that the liquid-side property has the increasing trend, a blockage of the refrigerant conduit subsystem is determined to have caused the shutoff switch to trip.

Abstract: A network of wireless remote climate sensors in a heating, ventilation, and air conditioning (HVAC) system permits the creation of personalized microclimates within an enclosed space. In addition to collecting temperature and humidity data, the wireless remote climate sensors can detect whether the enclosed space is occupied by a human. Human detection is made possible by optional cameras, microphones, and gas sensors on the wireless remote climate sensors. As the human moves throughout the enclosed space, the HVAC system is able to track the human's movement using the wireless remote climate sensors. The HVAC system may adjust airflow to different portions of the enclosed space based on the human's location. The result is an efficient use of system resources to keep users at their ideal temperature.

Abstract: A heating, ventilation, and air conditioning (HVAC) control device is configured to record a plurality of actual occupancy statuses, to determine a plurality of corresponding predicted occupancy statuses, and to compare the plurality of predicted occupancy statuses to the plurality of actual occupancy statuses. The device is further configured to identify conflicting occupancy statuses based on the comparison. A conflicting occupancy status indicates a difference between an actual occupancy status and a corresponding predicted occupancy status. The device is further configured to identify timestamps corresponding with the conflicting occupancy statuses, to identify historical occupancy statuses corresponding with the identified timestamps, and to update the conflicting occupancy statuses in the predicted occupancy schedule with the historical occupancy statuses.

Abstract: An HVAC system with a reheat coil is described, the system includes a compressor, a micro-channel condenser and an evaporator. A reversing valve is connected to the compressor, the micro-channel condenser and the reheat coil. The reversing valve is used to direct the refrigerant from the compressor to the micro-channel condenser in a normal mode, and to direct the refrigerant from the compressor to the reheat coil in a reheat mode. The reversing valve can be switched from normal mode to reheat mode when a high pressure condition is detected at an input to the micro-channel condenser, and switched back from reheat mode to normal mode when the high pressure condition has resolved or an amount of time has passed. In the normal mode the refrigerant is returned from the reheat coil into a refrigerant line between the evaporator and the compressor through a restrictor.

Abstract: A network of wireless remote climate sensors in a heating, ventilation, and air conditioning (HVAC) system permits the creation of personalized microclimates within an enclosed space. In addition to collecting temperature and humidity data, the wireless remote climate sensors can detect whether the enclosed space is occupied by a human. Human detection is made possible by optional cameras, microphones, and gas sensors on the wireless remote climate sensors. As the human moves throughout the enclosed space, the HVAC system is able to track the human's movement using the wireless remote climate sensors. The HVAC system may adjust airflow to different portions of the enclosed space based on the human's location. The result is an efficient use of system resources to keep users at their ideal temperature.

Abstract: A method includes measuring a saturated suction temperature, receiving actual temperature value reflective of the measured saturated suction temperature, and determining whether the actual temperature value is less than a first pre-determined minimum threshold temperature value. If 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 and if the actual temperature value is less the second pre-determined minimum threshold temperature value, initiating the timer to operate for a modified time interval. If the timer has expired, the operation of the compressor is modified.

Abstract: An HVAC system includes an evaporator. The evaporator includes a sensor configured to measure a property value (i.e., a saturated suction temperature or a saturated suction pressure) associated with saturated refrigerant flowing through the evaporator. The system includes a variable-speed compressor configured to receive the refrigerant and compress the received refrigerant. The system includes a controller communicatively coupled to the sensor and the variable-speed compressor. The controller monitors the property value measured by the sensor and detects a system fault, based on the monitored property value. In response to detecting the system fault, the controller operates the compressor in a freeze-prevention mode, which is configured to maintain the property value above a setpoint value by adjusting a speed of the variable-speed compressor. This prevents or delays freezing of the evaporator during operation of the system during the detected system fault.