Abstract: An occupancy tracking device configured to receive sound samples, to identify voices within the sound samples, and to determine a first occupancy level based on the identified voices. The device is further configured to identify user devices connected to an access point and to determine a second occupancy level based on the user devices that are connected to the access point. The device is further configured to measure a signal strength of a network connection with the access point and to determine a third occupancy level based on the signal strength of the network connection with the access point. The device is further configured to determine a predicted occupancy level based on the first occupancy level, the second occupancy level, and the third occupancy level and to control a Heating, Ventilation, and Air Conditioning (HVAC) system based on the predicted occupancy level.

Abstract: A method of monitoring a heating, ventilation, and air conditioning (HVAC) system to detect installation location of at least one indoor air quality (IAQ) monitor. The method includes monitoring, by a controller, operation of the HVAC system, determining, by the controller, whether power exists at a duct terminal of the at least one IAQ monitor and responsive to a determination that the power exists at the duct terminal of the at least one IAQ monitor, configuring, the at least one IAQ monitor as being installed within a ductwork.

Abstract: A device is configured to operate a Heating, Ventilation, and Air Conditioning (HVAC) system. The device is further configured to determine that the speed of a combustion air inducer has exceeded a speed threshold value. The device is further configured to receive an audio signal from a microphone while operating the HVAC system, to identify an audio signature for the combustion air inducer from an audio signature library, and to determine the audio signature for the combustion air inducer is present within the audio signal. The device is further configured to determine a fault type based on the determination that the audio signature for the combustion air inducer is present within the audio signal.

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 is configured to regulate a temperature of a space. The HVAC system includes a single-stage compressor configured to compress a refrigerant used to cool air provided to the space and a controller communicatively coupled to the single-stage compressor. The controller determines that a demand response time period is starting at a start time. After determining that the demand response time period is starting at the start time, an operation schedule is determined indicating alternating portions of the demand response period during which the single-stage compressor is to be turned off and turned on. At or after the start time of the demand response time period, the controller begins operating the single-stage compressor according to the determined operation schedule.

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: A microchannel evaporator includes a plurality of microchannels. Each of the plurality of microchannels includes a first end and a second end. A first end-tank is coupled to each first end of the plurality of microchannels and a second end-tank is coupled to each second end of the plurality of microchannels. A second-fluid inlet is coupled to either the first end-tank or the second end-tank and configured to receive a fluid into the microchannel evaporator and a second-fluid outlet is coupled to either the first end-tank or the second end-tank and configured to expel the fluid from the microchannel evaporator. Each microchannel of the plurality of microchannels includes at least one bend along a length thereof.

Abstract: An air quality measuring device that includes a first chamber, a second chamber, a third chamber, and a fourth chamber. The first chamber includes a first inlet configured to receive a first airflow, a first outlet configured to receive a first portion of the first airflow, and a second outlet configured to receive a second portion of the first airflow. The second chamber includes a second inlet configured to receive the first portion of the first airflow and a first sensor disposed within the second chamber. The third chamber includes a third inlet configured to receive the second portion of the first airflow and a second sensor disposed within the third chamber. The fourth chamber includes a fourth inlet configured to receive the second portion of the first airflow and a third sensor disposed within the fourth chamber.

Abstract: A microchannel evaporator includes a plurality of microchannels. Each of the plurality of microchannels includes a first end and a second end. A first end-tank is coupled to each first end of the plurality of microchannels and a second end-tank is coupled to each second end of the plurality of microchannels. A second-fluid inlet is coupled to either the first end-tank or the second end-tank and configured to receive a fluid into the microchannel evaporator and a second-fluid outlet is coupled to either the first end-tank or the second end-tank and configured to expel the fluid from the microchannel evaporator. Each microchannel of the plurality of microchannels includes at least one bend along a length thereof.

Abstract: An HVAC thermostat assembly has a wall-plate connector that includes a wall-plate and wire connectors as a whole that allows for a thinner, more aesthetic design. In one instance, the HVAC thermostat includes a display unit with a wall-plate connector recess having a plurality of electrical connector pins extending outward to mate with a wall-plate connector. The wall-plate connector includes a wall plate with incorporated electrical terminals. Other assemblies and systems are disclosed.

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 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: A subcooling controller includes a sensor and a processor. The sensor measures one or more of a temperature external to a first heat exchanger that removes heat from carbon dioxide refrigerant, a temperature of the carbon dioxide refrigerant, and a pressure of the carbon dioxide refrigerant. The processor determines that one or more of the measured temperature external to the first heat exchanger, the temperature of the carbon dioxide refrigerant, and the pressure of the carbon dioxide refrigerant is above a threshold and in response to that determination, activates a subcooling system. The subcooling system includes a condenser, a second heat exchanger, and a compressor. The condenser removes heat from a second refrigerant. The second heat removes heat from the carbon dioxide refrigerant stored in a flash tank. The compressor compresses the second refrigerant from the second heat exchanger and sends the second refrigerant to the condenser.

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.

Abstract: A metering device may automatically control fluid flow through a valve. A control system may alter the automatic control of a metering device. In some implementations, a predetermined event may occur to alter the automatic control of the metering device.

Abstract: A system includes an electronic power converter and a controller. The electronic power converter supplies power to one or more motor drives of an HVAC system. The controller obtains a plurality of pulse width modulation (PWM) algorithms. Each PWM algorithm has an associated spectrum of frequencies. The controller further determines one or more resonance frequencies associated with the HVAC system. The controller also selects a first PWM algorithm from the plurality of PWM algorithms wherein the spectrum of frequencies of the first PWM algorithm lacks frequency peaks that overlap with the one or more resonance frequencies associated with the HVAC system. The controller further operates the electronic power converter according to the first PWM algorithm.

Abstract: A system includes a device and a payload warehouse. The device receives a user request to initiate a feature of the device. In response to receiving the request, device information is provided to a payload warehouse. The payload warehouse stores an inventory which includes a digital payload. The digital payload includes data, such as a digital certificate, which may be used by the device to implement the user-requested feature. The payload warehouse receives the device information provided by the device and determines an encryption vector based at least in part on the received device information. Using the encryption vector, the digital payload is encrypted. The encrypted digital payload is provided to the device.

Abstract: A method of operating an HVAC system includes compressing a working fluid using a compressor, removing heat from the working fluid using a condenser, removing pressure from the working fluid using an expansion valve, and transferring heat between airflow contacting an outer surface of one or more coils in an evaporator and the working fluid passing through the one or more coils. The method further includes detecting a leak of the working fluid using a leak detection sensor. The method further includes transporting at least a portion of the working fluid to a storage container and storing the working fluid in the storage container.

Abstract: A blower of an HVAC system includes an air inlet, an air outlet, a blower wheel with blades, a motor operable to cause the blower wheel to rotate, and a blower housing within which the blower wheel is positioned. The blower housing includes a top panel, a bottom panel, and a connecting panel. The top panel and the bottom panel are connected to the connecting panel. The top panel includes a curved edge extending from a bottom edge of the connecting panel to a top edge of the connecting panel. An expansion angle of the curved edge of the top panel changes as a function of position along the curved edge of the top panel. The bottom panel may have a shape corresponding to a mirror image to that of the top panel.

Abstract: A condenser coil of a system includes a subcool sensor. The subcool sensor includes a first thermistor positioned to sense a saturated liquid temperature of refrigerant flowing in a first portion of the condenser coil. The subcool sensor includes a second thermistor positioned to sense a liquid temperature of the refrigerant flowing in a second portion of the condenser coil. The second thermistor is coupled electronically in series with the first thermistor. The subcool sensor includes a signal output for transmitting a subcool signal from the subcool sensor. The signal output is coupled electronically to a first terminal of the first thermistor and a second terminal of the second thermistor. A controller of the system includes an input/output interface which receives the subcool signal from the subcool sensor and determines a temperature difference between the saturated liquid temperature and the liquid temperature based on the subcool signal.