An external unit group placed in a VRF system is basically the external environment, thus resulting in a large number of indoor units, a precision-controlled automation system with copper pipe and the system consists of circulating refrigerant.

The pair of copper pipe from the outdoor unit (gas and liquid) system returns again circulated through the indoor unit outdoor unit. Y-type copper connectors used to connect the joint name of each indoor unit's main copper pipe. Advanced control technology with individually controlled environments can be applied independently only done for areas that need air conditioning.

The need for non-energy is not wasted areas. The heart of the system creates a total capacity can be set very precise DC inverter compressor and modulating on the indoor unit which sets the gas flow electronic fluid control valves according to the needs of the room according to the demand for capacity from the indoor unit. So the whole system works only up to respond to the needs and energy consumption to a minimum.

In this way, an external unit group different capacities and up to 48 types of indoor units can be connected and each indoor unit can be controlled independently or in groups. As long as less than 50% of the total capacity of the indoor unit of the outdoor unit capacity and not greater than 0 can be created in the system in various combinations.

Indoor temperature in the VRF system (+) (-) are controlled to 0.5 ° C precision. Each unit as standard, which temperature and each indoor unit with the help of pressure sensors, the position of the distance or from other units to the outdoor unit determines the exact affecting the capacity requirements and the necessary requirements are communicated to the external unit via a two-wire polarity of a signal cable.

In the overall system by the external unit only needs to respond to fluctuations in capacity without any form of energy transfer is performed. Thus, regardless of the resistance of the number of units in the system or pipeline at peak performance, continuous performance monitoring of all the unit operation is provided.

Basically two-pipe VRF air conditioning systems and heat pumps designed two types of three-tube type heat recovery.