What is the difference between AHU and Chiller?

AHU and Chiller are both devices and systems used to treat air. AHU is the air handling unit, while Chiller is the air conditioning system. So how do p Differentiate, compare AHU and Chiller different?

Differences in the structure of AHU and Chiller

AHU (Air Handling Unit) – The air handling unit is a heat exchanger used in HVAC systems.

AHU is often used in pharmaceuticals, cosmetics, electronics, etc.

AHU is a system commonly used in commercial buildings and commercial centers

Structure of AHU:

– Fan

– Heat exchanger

– Cooler

– Air filter

– Protective cover

Structure of AHU

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The chiller system is also known as the central chiller system, which generates a cold source for the purpose of cooling objects and food. Chillers are usually produced in clusters rather than separately.

Central air-conditioning system Chiller is a factory producing cold water in the central air-conditioning system, using refrigerant as water. Through an evaporation vessel with an input temperature of 12 degrees and a given temperature of 17 degrees, the water will be cooled.

Structure of the Chiller system:

– Refrigeration compressors: There are 3 types of refrigeration compressors: spiral compressors, screw compressors, centrifugal compressors.

– Outdoor unit Chiller (Condenser beam tube).

– Chiller evaporator: There are 3 types of evaporators: dry evaporation, submerged evaporation, stainless steel evaporation.

– Control cabinet:

Structure of Chiller

How do AHU and Chiller operate differently?

When the room temperature is greater than the valve set temperature, the 3-way valve will open to allow cold water to flow through the entire heat exchanger.

When the cold water temperature is lower than the set temperature in the valve, the 3-way valve closes, cold water will continue to flow and bypass the bypass to the center.

At this time, the air before being put into AHU has been filtered through prefilter and bag filter. These parts must be hygienic so they need to be cleaned regularly. In cases where a higher level of air cleanliness is required, a Hepa filter will be used.

The air will come into contact with the inner heat exchanger of the AHU after being treated at the filter to produce cool air.

Finally, the air will enter a circulation chamber to blow cold air from the ducts to the air-conditioned rooms.

General structure of the AHU


The chiller cluster is the most important part of the chiller system used to produce chilled water at a temperature of about 7 degrees Celsius to supply chilled water to the FCU.

Systems using Chiller assemblies include:


Screw compressors: used for large capacity chillers.

Centrifugal compressors: Use with moderate cooling capacity.

Helical compressors: used for small and medium-sized chiller systems.

Condenser device:

– Chiller cooled by wind.

– Water-cooled chiller: The chiller system will have to use cooling tower here, and water cooling.

– Evaporation flask: Use an evaporator to cool water with the following two types:

Water flowing in the tube: Made of winged copper pipe.

When the refrigerant boils outside the tube, water will move through the tube. Evaporation flasks have been covered with heat and maintained at a temperature not below 70 ° C to help prevent water from freezing, and to prevent bottoming out.

Water flowing outside the pipe: It is possible to limit the explosion due to the freezing water which is an advantage compared to the water flowing in the pipe, but the cleaning is quite complicated.

Compressor evaporates the fluid to maintain the constant bat pressure in TBBH, then compresses the vapor to high pressure and high temperature, eventually condensing into liquid at TBNT through the pressure-reducing throttle valve and Water refrigerant temperature.

Cold water is pumped to FCUs to cool the air in the room. Cold water will heat up after heat exchange and return to TBBH to be cooled.

The principle of operation of Chiller

Compare the advantages of AHU and Chiller


Pannel has a special structure that creates a strong, lightweight structure, with high thermal insulation and anti-rust properties.

Low leakage

Cold bridges reduce condensation and save energy.

Wide capacity increases the diversity suitable for the works.

The heat exchanger design helps the device to respond well to laboratory tests and practical applications of life.

Low noise level.

ARI certificate.


Capacity ranges from 5 Ton to thousands of Ton.

Cold water piping system is designed compact, installation of high-rise buildings.

System longevity stable, high, durable.

There are many levels to reduce the load

Suitable for large or very large projects

Power saving, cost

The temperature is always stable

In accordance with the capacity of the customer.

Recently, INTECH differentiated and compared AHU and Chiller different based on 3 basic criteria: Structure, operating principle and advantages of each device. Just knowing the three criteria is not difficult to distinguish AHU and Chiller.


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