Do You Know All the 34 Components of the Air-cooled Multi-connected Unit?

2025-03-14

Multi-connected units, commonly known as "one-to-many", refer to a system where one outdoor unit is connected to two or more indoor units through pipes. The outdoor side adopts the air-cooled heat exchange form, and the indoor side adopts the direct evaporation heat exchange form.

The central air-conditioning system of multi-connected units solves the situation of traditional central air-conditioning where all units are turned on simultaneously. It can control the activation of indoor units more intelligently, which not only facilitates people's lives but also greatly saves energy consumption.

Do You Know All the 34 Components of the Air-cooled Multi-connected Unit?1741941367142

Analysis of the Advantages and Disadvantages of Multi-connected Units
Advantages:
There are fewer outdoor units, which will not affect the appearance of the building.
The construction cost is lower than that of water-cooled units, and the operating cost is relatively low.
The control is flexible, and some brands can even achieve remote control through a telephone and a modem.
The noise is relatively low, and the operation is quiet.
The installation is simple, no three-phase power supply is required, and the construction period is short.

Disadvantages:
There are limitations on the length of the refrigerant pipes and the height difference between the indoor and outdoor units, so it is not suitable for rooms with a large depth.
The static pressure outside the unit is small, and the air supply distance is short.
The cooling (heating) capacity of a set of units is limited and cannot meet the air-conditioning requirements of larger rooms.
Generally, one indoor unit requires a set of control circuits, and the wiring is cumbersome, making it prone to failures.
Analysis of Each Component of Multi-connected Units
The following is an interpretation of the functions of each component of the multi-connected unit:
Compressor (1): The heart of the refrigeration system, it sucks in the low-temperature and low-pressure gaseous refrigerant and discharges the high-temperature and high-pressure gaseous refrigerant. The compressor is the power source of the refrigeration system.
Compressor Heating Belt (2): It increases the temperature of the compressor, volatilizes the liquid refrigerant inside into a gaseous state, and avoids liquid slugging to the compressor. Generally, this heating belt really works when it is powered on for the first time after installation or when it is not turned on for a long time in winter.
Compressor Discharge Temperature Sensing Bulb (3): It detects the discharge temperature of the compressor and prevents the discharge temperature of the compressor from exceeding the set temperature, so as to control and protect the compressor.
High-pressure Switch (4): When the discharge pressure of the compressor exceeds the action value of the high-pressure switch, it immediately sends a feedback signal to stop the operation of the whole unit, achieving the purpose of protecting the compressor.
Oil Separator (5): It separates the lubricating oil in the high-pressure steam discharged by the refrigeration compressor. At this time, the refrigerant and oil in the separation system rely on the oil separator to prevent a large amount of refrigeration oil from entering the refrigeration system and the compressor from being short of oil. At the same time, through separation, the heat transfer effect in the condenser and the evaporator is improved.
Oil Equalizer (6): The function of the oil equalizer is to "balance the oil level between different parts of the air-conditioning system" to prevent partial lack of oil.
Check Valve (7): In the refrigeration system, it prevents the refrigerant from flowing in the reverse direction, prevents the high-pressure gas from entering the compressor in the wrong direction, and quickly balances the suction and discharge pressure of the compressor.
High-pressure Sensor (8): It detects the real-time high-pressure value of the refrigeration system. If the high-pressure value exceeds the set value, it will send a feedback signal to protect the compressor and perform other controls.
Four-way Valve (9): The four-way valve consists of three parts: the pilot valve, the main valve, and the electromagnetic coil. By turning on and off the current of the electromagnetic coil, the left or right valve plug can be opened or closed. Thus, the left and right capillary tubes can be used to control the pressure on both sides of the valve body, so that the slider in the valve body slides left and right under the action of the pressure difference, thereby changing the flow direction of the refrigerant to achieve the purpose of cooling or heating.
Condenser (10): The condenser cools the high-temperature and high-pressure refrigerant vapor discharged by the compressor. The high-temperature and high-pressure refrigerant gas condenses here and exchanges heat through forced convection with the air.
Fan (11): Its main function is to strengthen the convective heat exchange, enhance the heat exchange effect. It absorbs heat and dissipates cold during cooling, and absorbs cold and dissipates heat during heating.
Defrosting Temperature Sensing Bulb (12): It controls the reset temperature of defrosting. When the set temperature of the sensing bulb is reached, the defrosting will stop. It is used for defrosting detection and control.
Electronic Expansion Valve (13): The function of the electronic expansion valve is throttling. The main difference between it and the capillary thermal expansion valve is that its opening degree is controlled by a controller. It can adjust the opening degree of the valve port according to needs, thereby controlling the flow rate. Using an electronic expansion valve can make the flow rate adjustment more accurate, but the price is much higher.
Check Valve (14): It prevents the refrigerant from flowing in the reverse direction in the refrigeration system.
Subcooler Electronic Expansion Valve (15): When the control system is in the refrigeration operation, it controls the subcooling degree of the refrigerant in the liquid pipe, reduces the pipeline capacity loss, and increases the refrigeration capacity of the refrigeration system.
Subcooler Liquid Outlet Temperature Sensing Bulb (16): It detects the temperature of the liquid pipe and sends it to the control board to adjust the opening degree of the electronic expansion valve.
Gas-liquid Separator Inlet Pipe Temperature Sensing Bulb (17): It detects the temperature of the inlet pipe of the gas-liquid separator to avoid the compressor running with liquid return.
Subcooler Outlet Temperature Sensing Bulb (18): It detects the gas-side temperature of the subcooler, inputs it to the control board, and adjusts the opening degree of the expansion valve.
Gas-liquid Separator Outlet Pipe Temperature Sensing Bulb (19): It detects the internal state of the gas-liquid separator and further controls the suction state of the compressor.
Ambient Temperature Sensing Bulb (20): It detects the ambient temperature in which the outdoor unit operates.
Low-pressure Sensor (21): It detects the low-pressure value of the refrigeration system. If the low pressure is too low, it will send a feedback signal to avoid running at too low a pressure, which may cause compressor failures.
Gas-liquid Separator (22): The main function of the gas-liquid separator is to store part of the refrigerant in the system, preventing the compressor from liquid slugging and the refrigerant from being too much to dilute the compressor oil.
Unloading Valve (23): The main function of the unloading valve is to automatically control unloading or loading to avoid the dead zone of the pipeline, which may lead to excessive pressure.
Oil Return Solenoid Valve (24): Simply put, when there is little compressor oil, the solenoid valve opens, and the oil returns. When the oil is detected to be in place, the solenoid valve closes to ensure the supply of lubricating oil.
Pressure Balance Valve (25): It balances the suction and discharge pressure of the refrigeration system to ensure the successful startup of the compressor.
Oil Return Temperature Sensing Bulb (26): It detects the oil return temperature to prevent the oil return pipeline from being blocked or leaking.
Capillary Tube (27): It throttles and reduces the pressure. It throttles and reduces the pressure of the high-pressure Freon refrigerant from the condenser into a low-pressure Freon refrigerant, and then the refrigerant vaporizes and absorbs heat in the evaporator.
Subcooler (28): It is used to control the subcooling degree of the liquid pipe.
Drier-filter (29): It absorbs the moisture in the system.
Filter (30): The drier-filter mainly plays the role of filtering impurities and absorbing the moisture in the system.
Liquid Pipe Stop Valve (31): It stops the refrigerant and connects to the indoor unit.
Low-pressure Measuring Valve (32): It is used to detect the low-pressure value when the refrigeration system is running, or for charging refrigerant during operation.
Gas Pipe Stop Valve (33): It stops the refrigerant and connects to the indoor unit.