The short version
General information, not advice
- Recommended annually
- Ensures safety and efficiency
- Often required for warranty validity
- Usually costs £70–£120
An annual boiler service checks that your boiler is safe, efficient and working as it should. It is a separate thing from boiler insurance: one keeps the boiler in good order, the other pays out when it fails.
What happens during a service
A boiler service has to be carried out by a Gas Safe registered engineer. It is a full safety and performance inspection, not a quick visual check.
On the safety side, the engineer confirms their Gas Safe registration, checks for gas leaks, inspects the flue and ventilation, tests carbon monoxide emissions, and runs a combustion analysis with a flue gas analyser. They then look at the boiler itself, removing the casing where the manufacturer allows, inspecting the heat exchanger, checking the burner and ignition, examining seals and gaskets, and cleaning key components as needed. Finally they test how it performs: gas pressure and flow rate, the thermostat and safety devices, the expansion vessel and the system pressure.
The work is recorded in the manufacturer's handbook, a certificate is issued, and any advisory repairs are noted. A standard combi boiler service should take at least 45–60 minutes.
Why servicing matters financially
Servicing earns its cost in more than safety. Catching worn seals, corrosion or a blocked condensate pipe early avoids the larger bill of an emergency repair, and a well-maintained boiler burns less gas, which shows up on the bill.
It also protects cover you may already be paying for. Most boiler warranties require an annual service by a Gas Safe engineer, and missing one can invalidate a multi-year warranty. If you later claim under boiler cover, home emergency cover or landlord insurance, the insurer may ask for evidence of regular servicing, and a lack of maintenance can reduce or void the claim. Annual checks also lower the risk of carbon monoxide from faulty combustion, which is the part that isn't really about money at all.
Legal requirements
There is no law requiring a homeowner to service their boiler every year, though it is strongly advised for safety and to keep warranties valid.
Landlords have firm obligations. They must arrange an annual gas safety check by a Gas Safe registered engineer, give tenants the resulting Gas Safety Certificate (CP12), and keep the records for at least two years. Failing to comply can mean fines, invalid landlord insurance, criminal prosecution, and in severe cases imprisonment.
Gas Safe Register 0800 408 5500
Only engineers on the Gas Safe Register may legally work on gas appliances.
Key takeaways
- A boiler service is a full safety and performance inspection — not just a quick check.
- Annual servicing protects your warranty and insurance validity.
- Landlords are legally required to obtain a Gas Safety Certificate every year.
- Servicing improves efficiency and reduces long-term repair costs.
- Always use a Gas Safe registered engineer.
Common questions
How often should a boiler be serviced?
A boiler should be serviced once every 12 months. Most manufacturers require annual servicing by a Gas Safe registered engineer to keep the warranty valid.
How long does a boiler service take?
A standard combi boiler service usually takes 45–60 minutes. Larger or more complex systems may take longer.
How much does a boiler service cost in the UK?
The average cost is between £70 and £120, depending on your location, boiler type and engineer rates.
Is a boiler service the same as a Gas Safety Check?
No. A Gas Safety Check (CP12) is a legal compliance inspection required for landlords. A boiler service is more detailed and focuses on maintenance, performance and efficiency. Landlords often arrange both at the same time.
Can I service my own boiler?
No. Gas appliances must only be serviced by a Gas Safe registered engineer. It is illegal and unsafe for unqualified individuals to work on gas appliances.
What happens if I miss an annual service?
You risk invalidating your manufacturer warranty, breaching boiler cover terms, increasing breakdown risk and reducing efficiency.
Does boiler cover include an annual service?
Some boiler cover policies include an annual service, while others require you to arrange it separately. Always check your policy wording.
What is a CP12 certificate?
A CP12 is the official Gas Safety Certificate issued to landlords after a compliant annual gas safety inspection by a Gas Safe engineer.
Does regular servicing extend the life of a boiler?
Yes. Regular servicing can extend a boiler's lifespan from around 8–10 years to 12–15 years or more by identifying wear and preventing major faults.