What Does a Boiler Service Include?

Visual inspection

The engineer starts by checking the boiler's general condition, looking for signs of corrosion, leaks, or damage to the casing and visible pipework, along with checking the flue and ventilation are in good order. The area around the boiler is also checked to confirm there's nothing obstructing air flow or access.

Internal checks

• Checking the burner and heat exchanger for signs of scale, soot or damage
• Testing the flame picture and combustion to ensure the boiler is burning gas correctly
• Checking gas pressure and flow rate against the manufacturer's specification
• Testing safety devices, including the pressure relief valve
• Checking the condensate pipe and trap for blockages
• Inspecting seals and gaskets for wear that could develop into a leak

Performance and safety testing

The engineer will run the boiler through its heating and hot water cycles, checking it fires correctly, reaches temperature, and shuts down safely. A flue gas analysis may also be carried out to confirm the boiler is burning fuel cleanly and safely, which also protects against the risk of carbon monoxide.

Paperwork you should receive

• A service record detailing what was checked and any readings taken
• Notes on any parts that are worn or likely to need attention soon
• Confirmation the boiler is safe to continue using

What isn't included

A standard service is not a repair. If the engineer identifies a fault during the service, such as a failing component or scale build-up, this will usually need to be quoted and carried out separately, either then or on a follow-up visit.

How to prepare for a service visit

• Clear access to the boiler and, if possible, to any external flue terminal
• Have the boiler manual or model details to hand if you have them
• Note down anything that's seemed slightly off recently, even minor noises or delays in firing
• Make sure someone is available to let the engineer in for the full visit, as they may need to run cycles more than once

Why carbon monoxide safety is central to a service

One of the most important reasons for a regular service is checking that the boiler is burning gas correctly and safely venting the products of combustion. A boiler that's burning inefficiently, whether from a dirty burner, a partially blocked flue or a worn seal, can produce carbon monoxide, a gas with no smell or colour that's dangerous in a home. The flame picture check and flue gas analysis carried out during a service are specifically there to catch this before it becomes a safety issue, which is one of the clearest reasons servicing isn't something to skip even on a boiler that seems to be running fine.

What it costs and how it's booked

A boiler service is £99, or £160 if combined with a landlord gas safety certificate on the same visit. This is a fixed fee for the service itself; if the engineer identifies a fault that needs repairing, this is quoted and agreed with you separately rather than being included automatically. Booking your service well ahead of the colder months, ideally in late summer or early autumn, avoids the busiest period for breakdown callouts.

What happens if something's found

If the engineer identifies wear or a developing fault during the service, they'll explain what they've found in plain terms, including how urgent it is and what your options are. Some minor issues can be dealt with there and then if parts are carried on the van; others need a follow-up visit once a part has been ordered. Either way, you'll be given a clear quote before anything beyond the service itself is carried out.