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Chiller system (Central air conditioning system Chiller) is a type of machine that generates a cold source, from which it can cool objects and food, and is also a machine that produces cold water used in air conditioning systems. center. The water is cooled through the evaporator normally at 12oC và ra 7oC.

Chiller system consists of 5 basic components:

  • Water chiller center cluster
  • Chilled water piping system and chilled water pump
  • Load system used directly: AHU, FCU, PAU, PHE,...
  • Loading system for indirect use: Air duct system blowing through the room to be air-conditioned, Valves to adjust ducts, air outlet: VAV, Damper
  • The system of pumping and circulating water through the Cooling Tower (if any) for water-cooled chillers

Operation model

  • Red Cycle: The hot water cycle that is pumped into the Cooling Tower releases this heat to the environment
  • Green Cycle: The refrigerant gas cycle belongs to the Water Chiller cluster
  • Purple Cycle: Cold water circulation pump to AHU, FCU, PAU, PHE
  • Golden Cycle: Circulation from the duct system is blown into the conditioned room

Realistic system model


Cluster of Water Cooled Chiller

  • This is the center of the system, has the largest power consumption and has the highest cost compared to other devices.

Pumping system and cold water pipes

Water pump:

  • Responsible for pumping cold water through the Chiller system to the load for direct use
  • The water flow from the pump through the Chiller system must always be kept stable, without reducing or increasing the pump flow capacity by the inverter if there is no scientific combination from the system.


  • Usually black steel pipe is insulated with cold water line. Black steel pipe or copper pipe with hot water pipe leading to Cooling Tower. Today, many companies are starting to design and switch to PPR pipes for Chiller systems. A number of projects using this type of pipe are currently being used very well.
  • Depending on the flow, we choose the appropriate pipe size. The choice of pipe size should be based on the flow it carries: Too small a pipe will lead to large water pressure losses, along with the pipeline having to bear a higher pressure when working. In addition, too large pipes will increase the cost of construction and pipeline prices.

System AHU, FCU, PAU or MAU

AHU (Air Handling Unit), FCU (Fan Coil Unit), PAU (Primary Air Unit) are essentially the same but have different purposes.

  • AHU – Central air duct system moisture heat treatment unit: Divided into many auxiliary ducts entering the air-conditioned space. Thus, an AHU can have many different dust filter layers, many copper coil coils depending on the required processing conditions and be used for large spaces.
  • FCU (Fan Coil Unit): Used for small rooms or small areas, places where AHU's duct system cannot reach or depending on the requirements of some rooms in the area with temperature and humidity requirements different from the AHU being installed. Due to the limited production size, FCU does not handle humid heat as well as AHU. Therefore, with high requirements, we are forced to use additional PAU processors installed outside and duct connections for internal FCUs.
  • PAU (Primary Air Unit): Filtration, cooling, heating, dehumidification or humidification

Air duct system

  • Mixing fresh air and return air, this amount of air will be fed into the AHU or FCU to properly handle the temperature and humidity requirements of the air-conditioned space.
  • Besides, there are other duct systems such as return air ducts, exhaust ducts, stair booster ducts, etc.

Chiller control connection system

  • Each piece of equipment: Chiller, AHU, FCU, PAU,... all operate independently by the DDC controller. Along with that, DDC can also receive signals from sensors (sensors of humidity, temperature, air and water flow, CO concentration, etc.)2,…) and is pre-programmed and controlled by a computer, in addition, there is an integrated communication port.