Chillers are compression water coolers, and can be divided, according to the fluid used to cool the condenser, into air- or water-cooled units.
This division into air-water and water-water chillers is followed by a further differentiation according to the number of refrigerant circuits:
- single circuit chiller, normally fitted with one hermetic or semi-hermetic compressor
- two circuit chiller, which may use one or more compressors working in parallel, with a maximum of four per circuit
- multiple circuit chiller, fitted with just one compressor per circuit (up to a maximum of four)
The normal range of cooling capacities of the systems installed in Europe varies between 100 and 500 kW. This range includes air-cooled chillers, while water-cooled chillers may often have higher capacities.
For both types of systems, scroll compressors are used in the low-medium capacity range (up to 200 kW), while for higher capacities (300- 900 kW), screw and centrifugal compressors are prevalently used.
As the chiller requires significant energy for its operation, a great deal of effort has been focused on reducing energy requirements. Over the years, in fact, the average performance of refrigeration systems has been improved, and the efficiency of the compressors and the heat exchangers increased. Further gains are possible through the optimisation of the management of the units and systems

The system consists of programmable controllers,
user interfaces, software development tools, communication interfaces and remote management systems.
It is powerful yet flexible, and can be easily interfaced with the more widely used Building Management and proprietary supervisory systems.
It is a unique "family" of controllers, designed to be reliable, flexible, and provide the
functionality required by today's OEMs.
A wide range of software applications can be customised, setting the parameters for the appropriate configuration of chillers, heat pumps and condensing units:
- water cooled
- air cooled
- up to 4 circuits
- up to 8 compressors.

CAREL solution is made up of parametric controllers, in both the panel mounted and DIN rail versions, user interfaces, both local and remote, communication interfaces, input/output expansions and electronic expansion valve drivers.
A wide range of applications can be customised bysetting specific parameters, for chillers, heat pumps, and condensing units:
- water cooled
- air cooled
- up to two circuits
- up to 3 steps per circuit.
All controllers can be equipped with accessories to ensure maximum performance and energy savings, such as electronic expansion valves and ratiometric pressure transducers.

- BacNet™,

- Johnson Metasys®,

- TCP/IP,

- SNMP,

- LonWorks®,

- Modbus®,

- TREND.