Devices, methods, and systems for determining the cause of a fault in a heating, ventilation, and air conditioning (HVAC) system are described herein. One device includes a memory, and a processor configured to execute executable instructions stored in the memory to receive operational data associated with an HVAC system, receive control logic associated with a controller of the HVAC system, determine a cause of a fault occurring in the HVAC system based, at least in part, on the operational data associated with the HVAC system and the control logic of the controller of the HVAC system, and provide the cause of the fault occurring in the HVAC system to a user.

An air-conditioning apparatus according to the present disclosure includes a heat medium circulation circuit, a heat-source-side device, and a voltage drop device. In the heat medium circulation circuit, a pump, an indoor heat exchanger, and a flow control device are connected by pipes to circulate the heat medium. The pump sends a heat medium that contains water or brine and transfers heat. The indoor heat exchanger causes heat exchange to be performed between the heat medium and an indoor air in an air-conditioned space. The flow control device controls a flow rate of the heat medium in the indoor heat exchanger. The heat-source-side device heats or cools the heat medium before the heat medium is sent to the indoor heat exchanger. The voltage drop device reduces a voltage that is applied to the pump based on a value of a current that is supplied to the pump, in association with a flow rate of the heat medium in the heat medium circulation circuit.

An output inductance value controlling method, apparatus, and computer device for a multi-tap reactor. A single output port of the multi-tap reactor is correspondingly connected to a single relay, and each relay is connected to a general power supply of all air conditioner internal units. When in use, an air conditioning system acquires a motor speed and a phase current of each air conditioner internal unit separately, and then calculates a sum of motor powers of all the air conditioner internal units according to the motor speeds and the phase currents. The system matches a basic inductance value required by the air conditioner internal units according to the sum of motor powers, sets a current output inductance value of the multi-tap reactor according to the basic inductance value, and inputs the output inductance value into the corresponding air conditioner internal units.

An output inductance value controlling method, apparatus, and computer device for a multi-tap reactor. A single output port of the multi-tap reactor is correspondingly connected to a single relay, and each relay is connected to a general power supply of all air conditioner internal units. When in use, an air conditioning system acquires a motor speed and a phase current of each air conditioner internal unit separately, and then calculates a sum of motor powers of all the air conditioner internal units according to the motor speeds and the phase currents. The system matches a basic inductance value required by the air conditioner internal units according to the sum of motor powers, sets a current output inductance value of the multi-tap reactor according to the basic inductance value, and inputs the output inductance value into the corresponding air conditioner internal units.

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.

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.

An all-inclusive fluid flow device that can variably magnify differential pressure, measure, and control a flow of a fluid is described. Various procedures, including measuring, controlling, balancing, or calibration procedures can leverage a variably magnified differential pressure measurement. Differential pressure measurements can be measured across the fluid flow device such that a first pressure measurement is taken upstream of the fluid flow device while a second pressure measurement is taken downstream of the fluid flow device. Moreover, one or more of the various pressure measurements, and in particular the downstream pressure measurement, can be performed at stagnation zone where the flow has stagnated. Such can provide significant magnification and/or turndown capabilities and the magnification can vary based on a damper position and/or apertures dimensions.

A method of controlling signal transmission in a building control system including measuring a number of signal values associated with an environmental variable using a sensor of a wireless device, dynamically determining, by the wireless device, a noise threshold based on the number of signal values, combining a first signal value and a second signal value of the number of signal values using a mathematical relationship to determine a result associated with the first signal value and the second signal value, and periodically transmitting the first signal value from the wireless measurement device to a controller in response to the result exceeding the noise threshold.

A method of controlling signal transmission in a building control system including measuring a number of signal values associated with an environmental variable using a sensor of a wireless device, dynamically determining, by the wireless device, a noise threshold based on the number of signal values, combining a first signal value and a second signal value of the number of signal values using a mathematical relationship to determine a result associated with the first signal value and the second signal value, and periodically transmitting the first signal value from the wireless measurement device to a controller in response to the result exceeding the noise threshold.

A method and computing device for inferring an airflow of a controlled appliance operating in an area of a building. The computing device stores a predictive model. The computing device determines a measured airflow of the controlled appliance and a plurality of consecutive temperature measurements in the area. The computing device executes a neural network inference engine using the predictive model for inferring an inferred airflow based on inputs. The inputs comprise the measured airflow and the plurality of consecutive temperature measurements. The inputs may further include at least one of a plurality of consecutive humidity level measurements in the area and a plurality of consecutive carbon dioxide (CO2) level measurements in the area. For instance, the controlled appliance is a Variable Air Volume (VAV) appliance and a K factor of the VAV appliance is calculated based on the inferred airflow.