Upon detection of a leakage of refrigerant, a refrigerant recovery operation is performed for operating a compressor in a state where an outdoor expansion valve is closed. The refrigerant suctioned from an indoor unit passes through an outdoor heat exchanger so as to be liquefied and accumulated in an outdoor unit. When a low-pressure detection value by a pressure sensor decreases below a reference value, a termination condition for the refrigerant recovery operation is satisfied, and the compressor is stopped. Furthermore, when an abnormality in the refrigerant recovery operation is detected based on a behavior of the low-pressure detection value obtained until the termination condition is satisfied, the compressor is stopped to thereby end the refrigerant recovery operation. Also, guidance information for notification about an abnormality is output to a user.

An air conditioner and a control method thereof. The air conditioner includes an indoor unit including an indoor heat exchanger and an indoor fan, an outdoor unit connected to the indoor unit and including an outdoor heat exchanger, an outdoor fan, a compressor, an expansion valve, and a four-way valve, and at least one processor configured to perform a test operation by controlling the indoor unit and the outdoor unit. Based on an outdoor temperature being less than a predetermined reference temperature, the at least one processor is configured to determine whether the indoor unit and the outdoor unit operate normally, by continuously performing a heating operation and a defrosting operation during the test operation.

A leak detection system includes a sensor assembly (30) having a sensor housing (32), a leak sensor (60), and a 36 collection housing (34). The sensor housing (32) defines a first fluid inlet (40). The leak sensor (60) is disposed within the sensor housing (32). The leak sensor (60) is arranged to provide a signal indicative of a presence of the first fluid within an interior space of the transport refrigeration unit. The collection housing (34) is spaced apart from the sensor housing (32) and defines a second fluid inlet (80).

An operational efficiency apparatus comprising a sensor connected to a heat transfer system to detect efficiency of system and a display electrically connected to the sensor for indicating efficiency of the system based on data detected from the sensor.

Various methods and apparatuses are provided for monitoring and detecting gas leaks. A method of determining a gas leak with a sensor assembly is provided. The sensor assembly includes a primary sensing device and a reference sensing device. The method includes receiving, via the primary sensing device, a first oxygen concentration level reading of a given area. The method also includes receiving, via the reference sensing device, a second oxygen concentration level reading of the given area. The method further includes comparing the first oxygen concentration level reading and the second oxygen concentration level reading. Based on the comparison, the method still further includes causing a transmission of a signal that a gas leak is occurring in an instance in which the first oxygen concentration level reading and the second oxygen concentration level reading have a difference greater than a threshold difference. A corresponding gas detection apparatus is also provided.

A refrigerant cycle apparatus, that circulates a flammable refrigerant in a refrigerant circuit, includes: a gas-side cutoff valve; a liquid-side cutoff valve, where the gas-side cutoff valve and the liquid-side cutoff valve are disposed on opposite sides of a first portion of the refrigerant circuit; a detection unit that detects refrigerant leakage from the first portion into a predetermined space; and a control unit that sets a cutoff state in the gas-side cutoff valve and the liquid-side cutoff valve when the detection unit detects the refrigerant leakage from the first portion into the predetermined space. The cutoff leakage rate at the gas-side cutoff valve is higher than the cutoff leakage rate at the liquid-side cutoff valve.

A refrigerant leakage detection sensor for a heat pump includes a sensor casing, a circuit board enclosed by the sensor casing, and a gas sensor mounted on the circuit board. The gas sensor has a housing, a refrigerant reception area at an end of the housing allowing gaseous refrigerant to enter the housing, and a sensing element in the housing. The housing protrudes through an opening in the sensor casing so that the refrigerant reception area is arranged outside the sensor casing and the sensing element is positioned inside the sensor casing.

A refrigeration cycle apparatus includes an outdoor unit a plurality of indoor units a relay unit a refrigerant circuit and a controller The relay unit includes a plurality of high-pressure valves and a plurality of low-pressure valves The controller when an operation state of at least one of the indoor units is changed from a first state to a second state, judges, based on a degree of supercooling of an outlet of the outdoor heat exchanger or the indoor heat exchanger or based on a degree of superheating of a suction side of the compressor, whether an abnormality is present in the plurality of high-pressure valves or the plurality of low-pressure valves.

A method for diluting a leaked refrigerant in a refrigeration system according to an example of the present disclosure includes operating the refrigeration system in a purge mode based on at least one purge condition prior to initiating a compressor of the refrigeration system. A refrigeration system according to an example of the present disclosure includes a compressor configured to compress refrigerant in a refrigerant line, a heat exchanger configured to exchange heat with the refrigerant line in a heat exchange mode, a fan configured to pass air through the heat exchanger to an indoor space, and a controller configured to operate the refrigeration system in a purge mode based on at least one purge condition prior to initiating the compressor.

This equipment maintenance system includes an equipment information storage unit that stores equipment information pertaining to a plurality of installed equipment, a condition information storage unit that stores specification conditions for specifying an inspection subject from the plurality of installed equipment, and an equipment list generation unit that generates an equipment list of designated equipment that serves as inspection subjects. The equipment list generation unit compares the equipment information stored in the equipment information storage unit and the condition information stored in the condition information storage unit to thereby specify the designated equipment that serves as inspection subjects.