What happens during an annual boiler service?
Most people know they should have their boiler serviced every year, but fewer know what actually happens during a service – or why it matters. Here is what a thorough annual service involves, and how to get the most out of it.
Why service your boiler every year?
- Safety. A service checks that your boiler is burning gas safely and that fumes are being removed properly through the flue.
- Reliability. Worn or failing parts can often be spotted before they cause a breakdown.
- Efficiency. A boiler that is set up correctly uses gas more efficiently.
- Warranty. Most manufacturers require a yearly service to keep the warranty valid.
What the engineer checks
1. A look at the boiler and its surroundings
The engineer checks the boiler is correctly installed and mounted, that there is enough space around it, and that there are no signs of leaks, scorching or damage. They also ask whether you have noticed any problems.
2. The flue
The flue carries waste gases out of your home. The engineer checks it is intact, properly supported and sealed, and that the terminal outside is clear and in a safe position – not blocked by plants, new windows or extensions.
3. Combustion analysis
Using a flue gas analyser, the engineer measures what is coming out of the flue. This shows whether the boiler is burning gas cleanly and efficiently, and is one of the most important parts of the service.
4. Gas pressure and burner
They check the gas pressure and how the burner is working, comparing readings with the manufacturer’s figures.
5. Inside the boiler
Depending on the boiler and what the readings show, the engineer may open up the boiler to inspect and clean components such as the burner, heat exchanger, seals and electrodes, following the manufacturer’s instructions.
6. The condensate trap and pipe
Condensing boilers produce acidic water that drains away through a trap and pipe. The engineer checks these are clear – a blocked or frozen condensate pipe is a common cause of winter breakdowns in Tynedale.
7. Safety devices and controls
Safety devices are tested to make sure they shut the boiler down if something goes wrong. The engineer also checks the boiler responds properly to your thermostat and programmer.
8. System pressure and expansion vessel
On sealed systems, the engineer checks the system pressure and the expansion vessel, which helps prevent the pressure problems many households experience.
9. Paperwork
You should receive a record of the service. Keep it with your boiler paperwork – you may need it for warranty claims.
How to prepare
- Clear access to the boiler and the area around it.
- Have previous service records to hand if you have them.
- Make a note of anything unusual you have noticed – noises, pressure changes, error codes.
- If the boiler is in a loft, make sure the engineer can get to it safely.
When to book
The best time is late summer or early autumn, before you rely on the heating every day. It is also wise to book a service if a boiler has not been used for a long time, for example in a holiday cottage.
A reminder about safety
Only a Gas Safe registered engineer should service or repair a gas boiler. You can check an engineer’s registration on the Gas Safe Register, and the Health and Safety Executive publishes guidance on gas safety at home.
Ready to book? See our boiler servicing page or request a quote.
Frequently asked questions
How long does a boiler service take?
Usually around an hour, sometimes longer if something needs a closer look.
Is a boiler service the same as a gas safety check?
Not exactly. A service is a more detailed maintenance check of the boiler. A landlord gas safety check (often called a CP12) is a legal safety inspection of all gas appliances in a rented property.
What happens if the engineer finds a problem?
They will explain what they found, how serious it is and what it would cost to fix. Dangerous faults may mean the appliance has to be turned off until it is repaired.
