Multi-line system characteristics and common faults

Multi-line system characteristics and common faults

Multi-connection is commonly known as "one-to-many". A multi-connection system is an outdoor unit connected to multiple indoor units, and each indoor unit can be freely run/stopped, or grouped, or centralized. It is composed of an outdoor unit and an indoor unit connected by a refrigerant pipeline. The outdoor unit is composed of an outdoor heat exchanger, a compressor and other refrigerant accessories; the indoor unit is composed of a fan and a direct evaporator. An outdoor unit can deliver refrigerant liquid to several indoor units through pipelines. By controlling the refrigerant circulation of the compressor and the refrigerant flow entering each indoor heat exchanger, it can meet the indoor cooling and heating load requirements in a timely manner.

　　 1. The working principle of multi-line system:

The indoor temperature sensor controls the electronic expansion valve on the refrigerant pipeline of the indoor unit, and through the change of refrigerant pressure, the outdoor unit's refrigeration compressor is controlled by frequency conversion or the number of compressors, the number of working cylinders, and the throttle valve are changed. The cooling flow rate of the system is changed to achieve the purpose of changing the cooling capacity or the heat supply in the cooling or heating modes with the change of load.

　　 2. The characteristics of the multi-line system:

　　 1. Significant energy saving effect

　　Multi-on-line system can automatically adjust the compressor speed and change the refrigerant flow according to the system load changes to ensure that the unit runs at higher efficiency. Energy consumption is reduced during partial load operation and annual operating costs are reduced.

　　2, save building space



　　The air-cooled outdoor unit used in the multi-line system is generally installed on the roof and does not need to occupy the building area. The connection pipes of the multi-line system are only refrigerant pipes and condensate pipes, and the layout of the refrigerant pipelines is flexible. Compared with the water system, the use of the multi-line system can reduce the building floor height and reduce the building height while meeting the same indoor ceiling height. Cost.

　　3, convenient construction and installation, reliable operation

　　 Compared with the centralized air-conditioning water system, the multi-line system has a much smaller construction workload, a shorter construction period, and is very suitable for family situations. The system has fewer links, and the system operation management is safe and reliable.

　　 Three, meet the room use requirements of different working conditions

　　Multi-online system combination is convenient and flexible, and the system can be organized according to different use requirements to meet the use requirements of rooms under different working conditions. For the heat recovery multi-line system, in a system, part of the indoor unit is cooling while the other part of the indoor unit can be operated for heating. In winter, the multi-line system can provide cooling in the inner zone and heating in the outer zone, transfer the heat from the inner zone to the outer zone, make full use of energy, reduce energy consumption, and meet the air conditioning requirements of different zones.

　　 Fourth, common failures of multi-line systems

　　Common failure of multi-line system 1: Air conditioner does not work

　　 There are many reasons why the air conditioner does not work. When the air conditioner does not work, we can check the following items first:

　　 1. Whether the power is off.

　　2. Is the remote control broken?

　　 3. Whether the working parameters are set incorrectly.

　　4. Whether there is electromagnetic interference near the indoor unit to make it unable to receive the signal correctly.

　　 Common faults of multi-line system 2: The room temperature does not meet the design requirements

　　 The room cannot reach the design temperature may be because the outdoor unit exhaust temperature is too high, causing a protective shutdown. The causes of excessive exhaust temperature are:

　　 1. The indoor load is too small. Too small indoor load will cause the compressor suction pressure to be too high, so that the compressed exhaust temperature will be higher than the set value.

　　2, refrigerant shortage.

　　3, the pipeline is blocked, the indoor unit filter is blocked.

　　 5. The compressor lacks lubricating oil.

　　 6. There is air in the tube because the amount of refrigerant is unstable.

　　 Common failures of multi-line system 3: Some rooms are hot and cold

　　The phenomenon of cold and hot suddenly occurs because of the unstable cooling capacity. The reasons for the unstable cooling capacity may be:

　　 1. There is a lack of refrigerant in the tube, which cannot meet the cooling demand of the room.

　　 2. There is air in the tube, and the refrigerant does not flow smoothly in the tube, and the flow rate is sometimes large and sometimes small.

　　 3. The refrigerant distributor is damaged, and the amount of refrigerant in each room cannot be distributed normally.

　　 Common failures of multi-line system 4: The air-conditioning system does not heat

　　 The common reasons why the air conditioning system does not heat are:

　　 1. The four-way valve blows air, that is, the refrigerant in the four-way valve enters the exhaust pipe. The four-way valve stringing will increase the pressure and temperature entering the low-pressure side and the compressor. The increase in suction pressure will increase the load of the compressor, and the operating current will increase. After compression, the high pressure and discharge temperature will be higher than normal. .

　　 2. The connection or wiring of the low pressure pressure sensor is incorrect or the characteristic value is abnormal. The equipment cannot make correct actions according to the parameters.

　　 Common faults of multi-line system five: The pressure is unstable due to nitrogen filling and pressure maintenance

　　 The pressure is unstable during the pressure holding process. There are two main situations that can cause this problem:

　　 1. Leakage caused by welding quality problems at pipe joints. This situation can be discovered and resolved in the pressure holding stage of the pipeline system.

　　2, indoor and outdoor equipment leaked. The internal leakage intelligence of indoor and outdoor units can only be found when the entire air conditioning system is under pressure. This is the need to check the outdoor unit condenser and other connections. For indoor units, it is necessary to carry out exclusion checks one by one. This situation consumes a lot of manpower and material resources.