Chiller maintenance and lifespan: what to budget
Updated 23 October 2026 · SEO Dons Editorial
What does chiller maintenance cover?
SFG20, the maintenance specification standard created by BESA, describes planned preventative maintenance as a series of planned inspections, servicing or calibration procedures designed to maintain efficiency, ensure safety and help prolong the lifespan of an asset. Each SFG20 schedule sets out priority, frequency and skill level, and its air conditioning and refrigeration set lists chillers, condensers and control panels among its schedule areas. Those frequencies are licensed content, so this page does not reproduce them. The table shows the strands that come from law or from published engineering sources.
| Strand | What it involves | Where it comes from |
|---|---|---|
| Refrigerant leak checks and records | Checks at a frequency set by the charge, repairs, retests, records kept for 5 years | Environment Agency and Defra guidance on GOV.UK |
| Pressure system examination | A written scheme for periodic examination of protective devices, vessels and pipework | Pressure Systems Safety Regulations 2000 |
| Compressor care | Lubricant, bearings and wearable parts; magnetic-bearing designs without lubricated bearings change the list | CIBSE Journal; one manufacturer's service page |
| Heat rejection | For evaporative towers and condensers, water treatment, inspection, cleaning and disinfection, and legionella controls | Health and Safety Executive |
| Controls and safety devices | Protective devices sit in the pressure scheme; control panels are an SFG20 schedule area | Regulations; SFG20 |
One manufacturer's published service programme shows what diagnostics can add. It describes oil analysis, vibration analysis on a chiller running under full load, eddy-current testing of evaporator and condenser tubes, and an overhaul that replaces wearable parts before they fail, focused on the compressor. Treat these as options to ask about, not requirements. CIBSE Journal notes that magnetic bearings replace conventional lubricated bearings, so oil-related tasks depend on the compressor design. The types of chillers guide explains the compressor families, and the commercial chillers page covers the plant as a whole.
How often are refrigerant leak checks required?
Stationary air-conditioning equipment is covered, and the interval depends on the charge in tonnes of carbon dioxide equivalent.
| Charge (tonnes CO2 equivalent) | Requirement on GOV.UK |
|---|---|
| 5 to less than 50 | At least once every 12 months |
| 50 to less than 500 | At least once every 6 months |
| 500 or more | A leak detection system must be fitted, and checked every year |
Installing automatic leak detection allows the interval between checks to be doubled. If a check finds a leak, it must be repaired as soon as possible and the test repeated within a month. Records must be kept for 5 years: the quantity and type of gas at installation, gas added during maintenance, and the dates and results of mandatory checks. The Environment Agency may ask to see them. A company servicing equipment operated by others must be certified (the F-gas certificate check explains how to verify one), and the GB F-gas changes guide covers rule changes.
What other legal duties apply to a chiller?
Pressure systems. Under regulation 8 of the Pressure Systems Safety Regulations 2000, the user must not operate a system without a written scheme for periodic examination by a competent person, covering protective devices and the pressure vessels and pipelines where a defect may give rise to danger. The scheme must specify the nature and frequency of examination. Schedule 1 excludes a vapour compression refrigeration system whose compressor drive motors total no more than 25 kW, so larger plant is not caught by that exclusion. Whether a given machine is in scope is a question for a competent person; HSE points to its approved code of practice L122. HSE also expects suitable maintenance, including a whole-system programme that considers age, uses and operating environment.
Water-cooled plant. HSE says that if you have a cooling tower or evaporative condenser you should put in place measures to prevent or control legionella. Its guidance covers a cooling water treatment programme (microbial, corrosion, scale and fouling control and more) and inspection, cleaning and disinfection. See the cooling tower legionella guide.
How does maintenance affect efficiency and service life?
CIBSE Journal lists correct maintenance of the system among the factors affecting a refrigeration system's efficiency, alongside the evaporating and condensing temperatures, refrigerant, equipment and controls. It adds that a 1 K rise in evaporating temperature or drop in condensing temperature gives a 2 to 4% increase in COP. Cleaning and, for wet systems, scale and fouling control (which HSE lists within a water treatment programme) are the tasks aimed at the condensing side.
For service life, the best public data found is ASHRAE's service life database, whose filters are US regions and states. For centrifugal chillers it shows:
| Centrifugal chillers | Units | Median age | Age range |
|---|---|---|---|
| Replaced | 30 | 25.0 years at replacement | 7 to 42 years |
| Still in service | 209 | 18.0 years | 3 to 41 years |
Other types have far fewer entries: 16 air-cooled reciprocating, 9 air-cooled screw and 5 water-cooled screw chillers, too few to quote. ASHRAE states the data are provided as is without warranty. Read the table as a US sample of when units were replaced, not a prediction of how long yours will run.
When should replacement planning start?
There is no single age trigger: the 30 replaced centrifugal machines ranged from 7 to 42 years. Start the conversation when any of these appear.
- The leak-check record shows repeat leaks or repeated top-ups.
- The written scheme of examination, an overhaul report or diagnostics flag wear.
- The refrigerant is under regulatory or supply pressure; see the refrigerant GWP table.
- The plant approaches the ages in the ASHRAE sample, around 18 years for machines still running and 25 years at replacement for centrifugal units. Commission a condition report by then.
- The building's duty is changing or being refurbished.
What should a yearly chiller maintenance budget cover?
This page gives no prices, because no dated official source was found for chiller service costs. A budget line for each of these avoids surprises:
- Planned visits, set by the maintenance schedule in the contract.
- Leak checks, records and any leak detection system checks.
- The pressure system examination and repairs it triggers.
- Water treatment and legionella monitoring for wet heat rejection.
- Consumables and diagnostics: lubricant, filters, and oil or vibration analysis where specified.
- Reactive call-outs and parts, including a reserve for compressor overhaul.
The maintenance contract checklist shows how to compare scopes, and the chiller cost guide covers the purchase side. If you want a chilled water plant specified with its maintenance in mind, the commercial chillers page explains the process, and you can send an enquiry through the site's form.
Sources
Regulations and guidance are revised, so confirm the current text before relying on a figure. SFG20 frequencies are licensed and are not reproduced here.
- Checking F gas equipment for leaks, Environment Agency and Defra, GOV.UK, published 21 August 2019; checked 22 October 2026.
- Record F gas in equipment you own or service, Environment Agency and Defra, GOV.UK, published 21 August 2019; checked 22 October 2026.
- Certification for companies working on equipment containing F gas, Environment Agency and Defra, GOV.UK, last updated 21 August 2019; checked 22 October 2026.
- The Pressure Systems Safety Regulations 2000, regulation 8, legislation.gov.uk; checked 22 October 2026.
- The Pressure Systems Safety Regulations 2000, schedule 1, legislation.gov.uk; checked 22 October 2026.
- Using pressure systems, Health and Safety Executive; checked 22 October 2026.
- Evaporative cooling systems, Health and Safety Executive, updated 2026-01-14; checked 22 October 2026.
- What is SFG20?, SFG20 (BESA); checked 22 October 2026.
- Aircon and Refrigeration Maintenance Schedules, SFG20 (BESA); checked 22 October 2026.
- What Is Planned Preventative Maintenance?, SFG20 (BESA), 18 Feb 2026; checked 22 October 2026.
- Module 2: Refrigeration, CIBSE Journal, posted March 2009; checked 22 October 2026.
- Module 6: The quiet revolution in chillers, CIBSE Journal, posted July 2009; checked 22 October 2026.
- HVAC Service Life Database: cooling, ASHRAE Public Database, live database; checked 22 October 2026.
- ASHRAE Service Life and Maintenance Cost Database, ASHRAE Public Database, live database; checked 22 October 2026.
- Proactive Services and Maintenance, Daikin Applied UK, manufacturer's own page; checked 22 October 2026.
Common questions
Who can carry out a refrigerant leak check?
A company servicing air conditioning for others must be certified by an approved body, according to GOV.UK, and working without the correct certification is against the law. Check the certificate before booking.
What happens if a leak is found?
It must be repaired as soon as possible and the test repeated within a month to confirm the repair worked. GOV.UK says not having the right checks in place, or not fixing leaks, is breaking the law and can lead to a civil penalty.
Is a service the same as an overhaul?
They are different things. One manufacturer describes an overhaul as replacing wearable parts before they fail, focused on the compressor, which houses the most wearable mechanical parts. Ask a contract to say whether it includes one, and how often.
How long must maintenance records be kept?
F-gas records, including gas added and the dates and results of mandatory leak checks, must be kept for 5 years where the charge is 5 tonnes of carbon dioxide equivalent or more. The Environment Agency may ask to see them during an inspection.
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