What Does a Gas Boiler Service Include?
A gas boiler service is a yearly health check for your heating system, where a Gas Safe registered engineer inspects, tests, and cleans your boiler to ensure it’s running safely and efficiently.
It’s one of the simplest ways to prevent breakdowns, improve efficiency, and keep your warranty valid.
If you’ve ever wondered what’s included in a boiler service or what an engineer actually does, here’s a step-by-step guide to the process.
Why Service a Gas Boiler?
Much like a car, your boiler needs regular maintenance to run smoothly. Without it, small issues—like dirt buildup or worn components-can turn into costly repairs.
A gas boiler service helps:
- Detect potential faults before they cause breakdowns
- Ensure your boiler burns fuel efficiently, saving on energy bills
- Reduce the risk of dangerous carbon monoxide leaks
- Keep your manufacturer’s warranty valid
At PlusHeat, we recommend annual servicing to stay compliant with most warranty terms and for peace of mind that your boiler is safe.
Step-by-Step: What Engineers Check
A typical gas boiler service checklist includes
- Checking your boiler’s controls for correct operation
- Inspecting the internal components for wear or leaks
- Testing gas pressure and flow rates
- Ensuring safety devices work properly
- Looking for signs of corrosion or water damage
Every step is carried out by a Gas Safe registered engineer—never attempt DIY boiler servicing.
Visual Inspection and Efficiency Testing
Your engineer will perform a visual inspection first—looking for obvious signs of wear, leaks, or corrosion on the boiler’s exterior and surrounding pipework.
Next comes an efficiency test to ensure your boiler is using gas effectively. This helps spot wasted energy that could be adding unnecessary costs to your bills.
Carbon Monoxide and Flue Analysis
One of the most important parts of a gas boiler service is checking for carbon monoxide leaks. Using specialised equipment, the engineer measures emissions from your boiler’s flue.
They’ll check:
- Flue position and condition
- Gas combustion levels
- Signs of incomplete burning (which can produce dangerous CO gas)
If you don’t already have one, we strongly recommend installing a carbon monoxide detector—and if you suspect your boiler might be leaking carbon monoxide, here are the steps you should take.
Cleaning and Part Checks
Dust, soot, and limescale can all affect boiler performance. As part of the boiler service steps, your engineer will:
- Clean the burner and heat exchanger
- Remove debris from the pilot assembly (if applicable)
- Inspect and clean the condensate trap
- Check seals, fans, and ignition components
If any worn parts are found, they’ll advise on replacement before the issue causes a breakdown.
Service Certificate Explained
Once complete, your engineer will issue a service certificate confirming your boiler has been checked and is safe to use.
For landlords, this record is crucial to meet legal gas safety requirements. For homeowners, it serves as proof for warranty claims and future property sales.
How Long Does It Take and What Should You Prepare
A standard gas boiler service usually takes 30–60 minutes.
Before your appointment:
- Clear access to your boiler
- Ensure your heating and hot water are working so the engineer can run tests
- Have your service records ready if you want them updated
Gas Boiler Service Cost
So, how much does it cost to get all this done? In 2025, a one-off gas boiler service typically costs between £70 to £130, depending on your location and the engineer you choose.
But there’s a more affordable option.
With PlusHeat, you can get your boiler serviced every year for just £83.76—no hidden fees, no surprises. It’s often cheaper than a one-off visit and helps keep your heating running smoothly all year.
Conclusion
A gas boiler service isn’t just a tick-box exercise—it’s your first line of defence against breakdowns, high bills, and safety risks.
At PlusHeat, our Gas Safe engineers follow a full gas boiler service checklist to keep your heating system running efficiently all year round.
Book your annual boiler service today and enjoy peace of mind that your home is safe, warm, and efficient.
