Water chillers are central to many commercial and industrial cooling systems. They remove heat from water, or from a water and glycol mixture, which is then circulated through air handling equipment, production machinery or specialist processes.

A chiller may support comfort cooling in a commercial building, temperature control in a pharmaceutical environment or the cooling of machinery on an engineering site. When its performance drops, temperatures become unstable, electricity use can rise and wider operations may be disrupted.

Regular water chiller maintenance helps keep the system reliable, efficient and capable of meeting the demands placed on it.

What does a water chiller do?

A water chiller transfers heat from a circulating liquid into a refrigerant circuit. The heat is then released outside the system.

Air-cooled chillers use fans and condenser coils to reject heat into the outside air. Water-cooled chillers transfer heat into a separate condenser water circuit, which is commonly connected to cooling towers or other heat rejection equipment.

In many comfort cooling systems, chilled water leaves the chiller at around 6°C to 7°C and returns at approximately 12°C after absorbing heat from the building. Process cooling temperatures vary according to the machinery, product or operation being supported.

Whatever the application, reliable water flow, effective heat transfer and correct refrigerant operation are essential.

Why does regular chiller maintenance matter?

A chiller system brings together compressors, heat exchangers, pumps, sensors, controls and refrigerant components, with air-cooled systems also using condenser fans.

A fault in one area places additional strain on the rest of the system. Dirty condenser coils restrict heat rejection and increase operating pressure. Blocked strainers reduce water flow. Scale inside a heat exchanger limits heat transfer, forcing the chiller to run harder and for longer.

Planned maintenance helps to:

  • maintain cooling performance
  • control energy consumption
  • identify developing faults
  • protect compressors, pumps and other major components
  • reduce the risk of an unexpected shutdown
  • extend the working life of the equipment

This is especially important when a chiller supports production machinery, temperature-sensitive storage or a controlled environment. In these situations, the cost of losing cooling can be considerably higher than the cost of repairing the chiller.

How often should a water chiller be serviced?

For many commercial chillers, a professional service every six months is a sensible starting point. This allows one visit to take place before the main cooling season and another following the period of heaviest operation.

Quarterly inspections are often more appropriate when a chiller runs continuously, serves an industrial process or supports a business-critical environment. Routine visual and operating checks may also be carried out by the site team between professional visits.

The final servicing schedule should reflect:

  • the manufacturer’s instructions
  • the chiller’s operating hours and cooling load
  • its age, condition and service history
  • previous faults and alarms
  • the surrounding environment
  • the consequences of losing cooling

Maintenance plans can also be structured around recognised building maintenance schedules such as SFG20, alongside manufacturer guidance and statutory requirements.

These planned service visits are separate from any legally required refrigerant leak checks.

F-Gas leak checks and record keeping

Many commercial chillers contain fluorinated greenhouse gas, commonly known as F-Gas. In Great Britain, the person or organisation responsible for the equipment must ensure that the applicable leak checks are completed.

The minimum intervals are based on the refrigerant charge and its global warming potential, expressed as tonnes of carbon dioxide equivalent.

Refrigerant charge Standard maximum interval With automatic leak detection
5 to less than 50 tonnes CO₂e 12 months 24 months
50 to less than 500 tonnes CO₂e 6 months 12 months
500 tonnes CO₂e or more 3 months 6 months

Automatic leak detection is mandatory for most stationary equipment containing 500 tonnes CO₂e or more. The automatic detection system must itself be checked at least once every 12 months.

A limited exemption applies to qualifying hermetically sealed refrigeration and air conditioning systems containing less than 10 tonnes CO₂e.

Operators must also keep records for equipment containing 5 tonnes CO₂e or more. These records include:

  • the type and quantity of refrigerant
  • refrigerant added during maintenance
  • the dates and results of mandatory leak checks
  • recovered or disposed-of refrigerant
  • details of the certified companies carrying out the work

These records must be retained for five years.

Companies installing, repairing or maintaining stationary refrigeration and air conditioning equipment containing F-Gas must hold appropriate company certification. Pure Facilities holds the required F-Gas company certification through REFCOM, providing assurance that refrigerant work is carried out by appropriately qualified engineers.

This information reflects the GOV.UK guidance on checking F-Gas equipment for leaks, checked in August 2026. Regulations and guidance can change, so operators should confirm the current requirements for their equipment.

What is checked during water chiller maintenance?

The exact checks depend on whether the system is air-cooled or water-cooled, its compressor type, its application and the manufacturer’s instructions.

A planned service will usually include checks of:

  • operating temperatures and pressures
  • compressor performance and refrigerant circuits
  • refrigerant leakage
  • pumps, strainers and water flow
  • condensers and evaporators
  • fans and coils on air-cooled chillers
  • sensors, controls and alarm history
  • electrical connections and protective devices
  • signs of water, oil or refrigerant leakage
  • unusual noise, vibration or corrosion

Engineers should compare current operating data with earlier readings where these are available. A gradual change in pressure, temperature difference, compressor current or approach temperature can reveal a developing fault before the chiller shuts down.

Water condition affects chiller performance

The water side of the system has a direct effect on chiller efficiency and reliability.

Scale creates an insulating layer inside heat exchangers, reducing their ability to transfer heat. Corrosion damages pipework and components, while dirt or biological contamination can restrict water flow.

Blocked strainers, low system pressure and incorrect glycol concentration also affect performance. Glycol must provide the necessary frost protection without being excessively concentrated, as too much glycol reduces heat transfer and increases the amount of pumping energy required.

Maintenance should therefore consider:

  • water quality
  • system pressure and flow
  • strainer condition
  • signs of scale or corrosion
  • glycol concentration where applicable

Water-cooled chillers may also have condenser water circuits and cooling towers that require appropriate inspection, cleaning and water treatment. Depending on the site arrangements, this work may be managed by the chiller contractor, the facilities team or a specialist water treatment provider. Where the system incorporates a cooling tower or evaporative condenser, the site must also manage the risk from Legionella in accordance with its legal duties and relevant HSE guidance, including HSG274.

Signs that a water chiller needs attention

Changes in performance should be investigated rather than repeatedly reset or ignored.

Warning signs include:

  • difficulty reaching the required water temperature
  • unstable or inconsistent cooling
  • rising electricity consumption
  • frequent high-pressure or low-pressure alarms
  • repeated shutdowns
  • unusual compressor, pump or fan noise
  • excessive vibration
  • visible water, oil or refrigerant leakage
  • reduced water flow
  • the chiller running significantly longer than usual, or continuously while struggling to reach the required water temperature

One symptom does not always identify the fault. Poor cooling, for example, could result from low refrigerant charge, restricted water flow, dirty heat exchangers, faulty controls or a change in the cooling load.

Proper testing is needed to identify the cause.

Why process cooling chillers need closer attention

In a comfort cooling application, reduced chiller performance affects conditions within the building. In process cooling, it can directly affect machinery, production rates and product quality.

A process chiller may need to maintain a narrow temperature range throughout long operating periods. Changes in water flow, glycol condition or leaving water temperature can have an immediate effect on the equipment or process being cooled.

Maintenance should therefore consider the actual process requirements, not simply whether the chiller starts and runs. Engineers need to review load patterns, operating temperatures, alarms and the performance of pumps, heat exchangers and controls.

Sites where cooling is essential should also consider contingency planning. This could include alarm escalation procedures, backup plant, temporary chiller connections or an agreed response plan for an unexpected failure.

Should the chiller be maintained, repaired or replaced?

Regular maintenance extends equipment life, but older chillers eventually reach a point where continued repairs are no longer the most practical option.

Replacement should be considered when:

  • faults are becoming more frequent
  • essential parts are obsolete or difficult to source
  • the existing refrigerant creates future servicing difficulties
  • repair costs are becoming disproportionate
  • the chiller no longer meets the site’s cooling requirements
  • a newer system would offer a worthwhile efficiency improvement

The decision should consider the equipment’s condition, repair costs, energy performance, refrigerant type and the future needs of the site.

Planning a replacement before complete failure reduces disruption and gives the business greater control over timing and budgets.

Arrange water chiller maintenance with Pure Facilities

Pure Facilities provides water chiller servicing, planned maintenance and repair support for commercial and industrial sites across the UK.

Our engineers also work with commercial refrigeration, air conditioning, process cooling, air handling units and wider HVAC plant.

To arrange a water chiller service or discuss a suitable planned maintenance programme for your site, contact Pure Facilities.