What Is a Chiller? A Guide to How Cooling Units Work, Their Types and Maintenance

Behind the enormous systems that cool shopping malls, keep hospitals at a safe temperature and cool the production processes of large factories lies chiller (cooling unit) technology. This guide covers everything you need to know about these systems, which operate in hundreds of large-scale facilities across Turkey.

What Is a Chiller?

A chiller is a central cooling system that cools a liquid (usually water) and uses that chilled liquid — through fan-coil units, air handling units (AHU) or process equipment — to air-condition large spaces. It runs the classic refrigeration cycle made up of a compressor, condenser, expansion valve and evaporator, but at very large capacities and with a water-based distribution system.

Types of Chillers

Air-Cooled Chiller

It releases the condenser heat directly into the outdoor air; cooling is achieved by means of fans. It requires no water infrastructure, and its installation is more practical and economical. It is preferred in small-to-medium commercial buildings and in areas where water resources are limited. Because it depends on the outdoor temperature, its efficiency can drop in hot climates.

Water-Cooled Chiller

The condenser heat is rejected to the atmosphere through the water in the cooling-tower circuit. It provides 15–25% higher energy efficiency than the air-cooled type. It is the standard solution for large hospitals, plaza buildings and production facilities. The cooling tower requires additional investment and maintenance.

Magnetic-Bearing (Turbo) Chiller

The compressor shaft rotates on the principle of magnetic levitation without mechanical contact, which minimizes friction and wear. With high energy efficiency (COP in the 6.0–8.0 range) and low noise levels, it is preferred in large-capacity projects. Its initial investment cost is high, but over the long term it is the option with the lowest operating cost.

Absorption Chiller

It runs on heat energy instead of electrical energy. It is fed by factory waste heat, geothermal energy or a natural-gas burner. It is a suitable alternative for industrial facilities where the cost of electricity is high and heat energy is abundant.

How Is Chiller Capacity Selected?

Chiller capacity is expressed in tons of refrigeration (TR) or in kW of cooling. 1 TR ≈ 3.517 kW of cooling. The capacity selection should be made by a specialist engineer, taking into account the m² of the space to be cooled, the heat-load calculation, the density of people and equipment in the space, part-load performance and a safety factor. A system selected too large leads to a short-cycling problem; one selected too small leads to insufficient cooling and overloading of the compressor.

Operations Performed in Chiller Maintenance

• Compressor oil analysis and, if needed, an oil change
• Evaporator and condenser tube cleaning (mechanical or chemical)
• Measurement of refrigerant gas pressure and temperature values
• Refrigerant gas leak test and scale analysis in the water circuit
• Testing of the control panel, sensors and alarm systems
• Fan motor and pump current measurements
• Cooling-tower fill, pump and valve checks (in water-cooled systems)

Chiller Maintenance Frequency

In systems that run around the clock, maintenance should be carried out four times a year (at the start of each season). For seasonally operated systems, twice a year is sufficient. Scale and biological-contamination maintenance in the water circuit should additionally be done in quarterly cycles. Chiller maintenance must always be performed by a licensed refrigeration technician.

Get in touch with our team for chiller maintenance, fault diagnosis and spare-part supply. Our technicians, experts in every brand and model, are at your service.