An air-conditioning apparatus includes a controller configured to operate in a heating normal operation mode and a heating-defrosting operation mode. In a case of switching from the heating normal operation mode to the heating-defrosting operation mode, the controller makes a selection from an initial control mode 1, in which control is performed such that an initial frequency of the compressor is set to a predetermined maximum frequency and an initial opening degree of the flow control device is set to an opening degree lower than a predetermined maximum opening degree, and an initial control mode 2, in which control is performed such that the initial opening degree of the flow control device is set to the predetermined maximum opening degree and the initial frequency of the compressor is set to a frequency lower than the predetermined maximum frequency, to execute the heating-defrosting operation mode.

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for monitoring an HVAC system. One of the methods includes receiving pressure data from one or more sensors monitoring a supply air duct of an HVAC system at a property that indicates a pressure in the HVAC system; determining, using the pressure data, that the pressure satisfies a pressure threshold for the HVAC system; and in response to determining that the pressure satisfies the pressure threshold, adjusting an actuator-controlled damper between the supply air duct and a return air duct or adjusting a fan speed of the HVAC system.

In one aspect, a heat exchanger system is provided that includes a cooling system and a sensor configured to detect a variable of the cooling system. The heat exchanger system includes processor circuitry configured to provide the variable and a plurality of potential operating parameters of the cooling system to a machine learning model representative of the cooling system to estimate at least one of energy consumption, water usage, and chemical usage for the potential operating parameters. The processor circuitry is further configured to determine, based at least in part on the estimated at least one of energy consumption, water usage, and chemical consumption, for the potential operating parameters, an optimal operating parameter of the cooling system to satisfy a target optimization criterion.

A controller has a timer operation mode in which the operation of a refrigeration cycle that operates as a heat source or a cold source is started before a set operation start time of an indoor fan by a preliminary operation time period. In the timer operation mode, the controller calculates a heat capacity of water or brine, calculates a heat storage amount of a second heat medium from a temperature detected by a temperature sensor and the heat capacity, and determines the preliminary operation time period from the heat storage amount. By determining the preliminary operation time period in this manner, timer operation can be performed such that air at an appropriate temperature is blown from an indoor unit at the operation start time of the indoor fan, from the initial time at which an air conditioning apparatus is installed.

An HVAC system includes a unit cooler, which includes a first evaporator coil, a second evaporator coil, and a blower. The HVAC system further includes a first sensor, a second sensor, a first valve, a second valve, and a controller. The controller actuates the blower to direct air to flow over the first evaporator coil and the second evaporator coil, receives measurements from the first sensor and the second sensor, initiates a defrost cycle for the first evaporator coil by transmitting instructions to close the first valve to prevent the flow of refrigerant into the first evaporator coil, transmits instructions to open the first valve when the defrost cycle for the first evaporator coil has terminated, and initiates a defrost cycle for the second evaporator coil by transmitting instructions to close the second valve to prevent the flow of refrigerant into the second evaporator coil.

An air-conditioning apparatus includes an outdoor unit, multiple indoor units, and an intermediate unit. The indoor units each include a flow control device and an indoor controller. The intermediate unit includes an intermediate heat exchanger, a circulation device, and an intermediate controller. When at least one indoor unit starts operating, the intermediate controller determines whether a flow rate of a heat medium flowing into the intermediate heat exchanger is greater than or equal to a minimum flow rate. In response to determining that the flow rate is less than the minimum flow rate, the intermediate controller transmits an open instruction signal, representing an instruction to increase the opening degree of the flow control device, to the indoor controller of the indoor unit that is in a non-operation state. The indoor controller increases the opening degree of the flow control device in response to the received open instruction signal.

A refrigerant leakage notifying device includes a refrigerant sensor, a determination unit, a notification unit, and an output unit. The refrigerant sensor detects a refrigerant and outputs a detection signal according to a detection result. The determination unit receives the detection signal outputted from the refrigerant sensor and determines leakage of the refrigerant in accordance with the detection signal received. The notification unit notifies leakage of the refrigerant with at least one of sound and light in a case in which the determination unit has determined that the refrigerant is leaking. The output unit is provided separately from the refrigerant sensor. The output unit outputs a test signal to the determination unit. The test signal is a signal that the determination unit has determined that the refrigerant is leaking in a case in which the determination unit receives the signal.

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.

The present disclosure discloses a networking method device and terminal for an air conditioning unit. The networking method includes: detecting an outside ambient temperature after a target networking indoor unit is started; determining a target operating mode of the target networking indoor unit according to the outside ambient temperature; detecting a system pressure value of a multi-split air conditioning system after an operating duration of the target networking indoor unit in the target operating mode is greater than a preset operating duration; and determining whether the target networking indoor unit belongs to a target networking system according to the system pressure value.

A dedicated outdoor air system (DOAS) includes an outdoor unit providing a temperature at a set dry bulb temperature and dew point temperature in a wide variety of outdoor air conditions. The DOAS monitors and modulates suction pressure and head pressure in order to maintain a dew point temperature of 45° F. for supplied air. Furthermore, the DOAS includes a hot gas reheat coil, allowing the system to heat the air to 73° F. before supplying the air to a space, even where outdoor air temperature is lower than 73° F. In one embodiment, the DOAS includes an energy recovery ventilator (ERV) in order to precondition the air to decrease the amount of energy needed to operate the DOAS in some conditions.