Boiler Service: What to Expect and What It Costs
What a Gas Safe engineer checks during an annual boiler service, how long it takes, typical UK prices, how to prepare, and what the report should tell you.
An annual boiler service is the single most useful maintenance habit for a gas-heated home. It keeps the boiler safe, spots small faults before they become winter breakdowns and often protects the manufacturer's warranty. Yet many people are unsure what actually happens, and what they should ask. Here is what a proper service involves.
Who can do it
Anyone working on a gas appliance in the UK must be on the Gas Safe Register. Ask to see the engineer's Gas Safe ID card, which shows their photo, registration number and which types of gas work they are qualified for. You can check the register on the Gas Safe website using their number. Oil boilers need an OFTEC-registered technician, and LPG appliances need an engineer qualified for LPG.
What the engineer should do
A thorough service for a typical gas boiler usually includes:
- Visual check of the boiler, flue and surrounding area for damage, leaks or poor installation.
- Removing the casing and inspecting internal components, including the heat exchanger, burner, ignition and seals.
- Checking the flue for correct fitting, terminal position and that gases are safely discharged.
- Gas pressure and flow checks, and flue gas analysis to confirm the boiler burns efficiently and safely.
- Testing safety devices such as overheat controls and flame failure devices.
- Cleaning key components, as needed.
- Checking system pressure, expansion vessel and controls like thermostats and timer.
- Testing for carbon monoxide around the appliance.
A service typically takes 30 to 60 minutes, depending on the boiler type and condition.
What a service is not
A service is not a full system health check. It does not necessarily include bleeding radiators, power flushing, checking every radiator valve or inspecting other gas appliances such as a hob, unless you ask. If you want the full picture, tell the engineer when booking.
Typical costs
Prices vary by region and provider. Typically a standard boiler service in the UK costs around £70 to £120, with higher costs in some areas or for older or more complex appliances. Landlord gas safety checks are often priced similarly. Be wary of unusually low prices that leave out parts of the work, and ask what is included, and whether any repairs are charged separately.
How to prepare
- Make sure the engineer can reach the boiler. Clear cupboards and the area beneath it.
- Have your previous service record, boiler manual and warranty details to hand.
- Note any symptoms: noises, low pressure, cold radiators, hot water changes.
- Let the engineer know about any smells or alarm activations.
- Ensure someone over 18 is home.
After the service
You should receive a record or service report showing what was checked and any findings. If the engineer finds problems, they might classify them as follows:
| Classification | Meaning |
|---|---|
| Immediately dangerous | The appliance must be disconnected |
| At risk | Unsafe and should be turned off; repair recommended |
| Not to current standards | Not dangerous now, but worth improving |
Ask for a clear explanation and a written quote for repairs. You do not have to accept repairs from the same engineer; you can get another quote.
When to service
Autumn is busiest. Booking in spring or summer often means more choice and easier appointments. Make it an annual date you can remember, such as the same month as your car's MOT.
Signs the boiler needs attention before the service is due
- Yellow or orange flame instead of blue
- Black marks around the appliance
- Frequent pressure loss
- Banging, whistling or kettling noises
- Pilot light going out
- Condensation on windows, or soot
If you suspect carbon monoxide, stop using the appliance, open windows and get help; see our carbon monoxide alarm guide. For a suspected gas leak, call 0800 111 999.
If you rent
Landlords in England and Wales must arrange an annual gas safety check by a Gas Safe registered engineer and give tenants a copy of the record. That check is a safety inspection and not the same as a manufacturer's service, so ask your landlord about both. See tenant vs landlord responsibilities.
If you want to book, search Compito for heating engineers, compare ID-verified providers by postcode and send a request. Always confirm Gas Safe registration yourself.
Frequently asked questions
Is a boiler service a legal requirement for homeowners?
No, not for owner-occupiers, but it is strongly recommended and may be a condition of warranties and insurance. Landlords do have a legal duty to carry out gas safety checks.
How long does a boiler service take?
Usually around 30 to 60 minutes. Older or more complicated systems can take longer.
Can I service my own boiler?
No. Work on gas appliances must be done by a Gas Safe registered engineer. You can do simple checks such as pressure and bleeding radiators.