Chiller systems

A chiller cools water or a glycol mix and pumps it through a pipe network to fan coil units or air handling units across the building. It suits shopping centres, hotels, hospitals, office buildings and industrial sites with large cooling loads.

We handle everything from design and equipment selection to installation, integration with the fan coil network and technical support.

Chiller types

Air-cooled chiller: Usually roof-mounted; no cooling tower required.
Water-cooled chiller: Works with a cooling tower; higher efficiency in large buildings.
Heat pump chiller: Provides both cooling and heating.

How a chiller–fan coil system works

In a chiller–fan coil system, water or an antifreeze solution, not refrigerant, circulates between the central plant and the room units. The chiller cools the fluid and a pump station sends it through insulated pipework to the fan coils in the rooms, which work like the indoor units of a split system.

Advantages

Scalability: The number of fan coils on one chiller is limited in practice only by the chiller's capacity.
Minimal footprint: A large building can be cooled by a single chiller. There are no outdoor units on the façade, so the building keeps its appearance.
No practical distance limit: Pipe runs between the chiller and the fan coils can reach hundreds of metres, because losses per metre in a liquid heat-transfer medium are lower than in refrigerant systems.
Lower pipework cost: Standard water pipes and fittings are used, and hydronic balancing is easier and cheaper than in refrigerant systems.
Safety: The refrigerant is contained in the chiller, installed outdoors on the roof or at ground level. Inside the building a pipe failure only means a risk of water leaks, which automatic shut-off valves reduce.

Limitations

A chiller–fan coil system does not ventilate: it cools the rooms but brings in no fresh air. Ventilation is usually added with a central air handling unit (AHU) fed with chilled water from the same chiller. In energy use the system trails VRF, but VRF capacity is limited, whereas a chiller can serve very large buildings.

Types of chillers

Modern chillers range from 5 kW to 9,000 kW, enough for anything from a small cottage to a high-rise building. They differ in the following ways:

Condenser cooling: In air-cooled models a fan cools the condenser. Water-cooled models are more compact and less expensive, but need running water or a cooling tower.
Heating mode: Heat pump (reversible) models can both cool and heat the heat-transfer fluid.
Construction: In a packaged chiller the condenser is built in. With a remote condenser the chiller stands indoors and the condenser goes on the roof, which makes servicing easier, improves reliability and allows plain water instead of antifreeze as the heat-transfer fluid.
Fan type: Chillers with axial fans cost less but develop little air pressure, so they are installed only in the open. Chillers with centrifugal fans can be placed indoors and discharge air through a duct.
Absorption chillers: Work with water and a lithium bromide solution instead of refrigerant, driven by hot water, steam or a gas burner. Suitable where electrical capacity is limited.

Pump station (hydronic module)

The pump station circulates the heat-transfer fluid between the chiller and the fan coils. The fluid is water or a 10–40% solution of ethylene or propylene glycol.

Circulation pump: maintains the required pressure in the system
Expansion vessel: absorbs the change in fluid volume as temperature varies
Shut-off valves: for servicing, filling and draining, and venting air
Buffer tank: prevents short-cycling of the compressor and extends its life
Control and protection system: raises an alarm and stops the system on overpressure or a risk of freezing

Where it is used

Administrative and office buildings, hotels and shopping complexes. The system calls for highly qualified design, the installation work is substantial, space is needed for the chiller, condenser and hydronic module, and it requires regular maintenance in operation.