Boiler Service
What does it involve and why do you need one?

What is a boiler service?

A boiler service is a set of tests and checks a boiler engineer conducts on a boiler to ensure that it is running as smoothly, efficiently, and safely as possible.

Only Gas Safe registered engineers are allowed to service boilers. The Gas Safe Register is the official list of all engineers that are legally permitted to carry out work on gas appliances.

Why should I get my boiler serviced?

Keep your home safe

The most important reason why you should get your boiler serviced is to keep you and the people in your home safe. As gas boilers ignite gas to produce heat, they are potentially explosive appliances. During a boiler service, your engineer will check if there are any faults or damage within the boiler that could cause an explosion.

As previously mentioned, a gas boiler burns gas as fuel. The incomplete burning of gas can produce Carbon monoxide (CO). This can happen when a gas boiler has been poorly installed, maintained, and/or serviced.

Carbon monoxide is a highly poisonous gas that you can’t see, taste, or smell. Even small amounts of carbon monoxide can cause poisoning, and long-term exposure can result in paralysis, brain damage, or even death.

During a boiler service, your engineer will check for leaks in your boiler, its pipework, and its flue. Your engineer will be equipped with a tool called a flue gas analyser which detects carbon monoxide leaking from the flue.

For a more in-depth read on how to spot a carbon monoxide leak, the symptoms, what to do if you suspect a CO leak, and much more, click here.

Potentially save money on your heating bills

The efficiency of your boiler has a direct impact on how much you pay on your gas bill. The less efficient your boiler is, the higher your gas bill will be.

The efficiency of a boiler is the percentage of the power output it uses to generate heat. For example, if your boiler is 90% efficient, it will use 90% of its power to heat up your home and only 10% of its power would be wasted.

To put this into money terms, for every £1 spent on a 90% efficient boiler’s energy usage, 90p would have gone into heating your home, while only 10p would have been wasted.

If a boiler has leaks or faulty or damaged parts, it could lose some efficiency, which will result in you paying more on your energy bills. During a boiler service, your engineer will be able to spot problems that may be affecting your boiler’s ability to run at its maximum efficiency.

Catch faults early before they become a serious problem

As only Gas Safe registered engineers are permitted to remove a boiler’s casing and work on the appliance, you will not be able to know if any problems are developing inside your boiler. You may have a fault that needs fixing before it damages your boiler and causes a breakdown.

During a boiler service, your gas engineer will be able to spot potential problems and fix them before they become a major and costly issue.

Avoid costly repair bills

As previously mentioned, your boiler may have a fault that can only be identified by a trained gas engineer. If these problems go unnoticed, eventually they will cause a boiler breakdown. If your boiler breaks down, it could cost hundreds of pounds to repair, and if the damage is irreparable and you need a new boiler, you could be looking at a few thousand pounds to buy a replacement boiler.

Keep your boiler warranty or guarantee valid

Boiler warranties and guarantees are contracts made between the boiler manufacturer and the boiler owner that in the event of a fault or breakdown, the manufacturer will cover the cost of repairs and labour, or if needed, a replacement boiler will be provided. Many manufacturers offer warranties and guarantees ranging from 2 to 15 years.

Part of the terms and conditions to keep a boiler warranty or guarantee valid is to have the boiler serviced once a year by a Gas Safe registered engineer. If you fail to have your boiler annually serviced, you will invalidate your warranty or guarantee and will not be able to claim free repairs, boiler parts, or a free replacement from the boiler manufacturer.

If you have previously failed to have your boiler serviced or the warranty has expired, you may want to consider boiler cover. Boiler cover is a policy that covers your boiler in the event of a breakdown, and many policies include an annual boiler service.

For more information on what boiler cover is, and its benefits, click here.

Further information on boiler warranties and guarantees:

• Baxi boiler warranty
• Ideal boiler warranty
• Worcester Bosch guarantee

Landlords must provide all gas appliances with an annual gas safety check

If you are a landlord, it is a legal requirement to conduct a gas safety check every year. These checks ensure that all gas appliances in a rented property are safe for use and won’t put tenants at risk.

A boiler service includes all the safety checks and tests that are included in an annual gas safety check and also includes other checks, tests, and cleaning that are specific to your make and model of boiler to ensure it is working efficiently.

For information on the legal responsibilities of landlords in regards to gas appliances in a rented property, click here.

What does a boiler service include?

A typical boiler service will include:

A visual inspection

The first thing the boiler engineer will do is conduct a visual inspection of the outside of the boiler and the connected pipework. This is to ensure that everything is installed and positioned correctly. During this initial visual inspection, the engineer will look for signs of damage, corrosion, and leaks. The engineer will also conduct a visual inspection of the flame to see if it is igniting as it should.

Removing the boiler’s casing and inspecting the inside

Your boiler engineer will remove the boiler's casing to inspect the main components. During this, they will check to see if key components such as the heat exchanger, burner, injector, and other components are working correctly and aren’t damaged or faulty. They will also clean the boiler and its parts if necessary, in line with the manufacturers’ instructions.

Check the flue

The engineer will check that the boiler’s flue is fitted correctly and is free of obstruction. A boiler flue is the outlet through which steam and toxic gases, such as carbon monoxide are safely expelled.

If a boiler flue is blocked, potentially fatal gases such as carbon monoxide will have nowhere to go other than back inside your home, which could cause serious illness and even death.

Check the boiler controls and operation

The boiler’s functions, controls, and safety devices will be checked to ensure they are functioning correctly.

Conduct a record

As the engineer undertakes the tests and checks, they will make a record of each result. These checks will include the checks previously mentioned and more. Some of the checks include the following:

• Check the boiler’s flame failure device


• Check all seals and valves


• Check electrical connections


• Ensure there is adequate ventilation


• Check that the boiler is located away from combustible materials


• Check the thermostat


• Dismantle and clean the boiler pilot assembly and gas injector/spark electrodes


• Check and adjust boiler pressure if needed


• Clean the heat exchanger and check for leaks or soot

The engineer will fill out their checklist and provide a record of all the completed checks. A copy of the checklist will be left with the homeowner, which they will be able to refer to for future inspections or if any problems arise.

Fire up the boiler

After all the checks and tests have been completed, the engineer will turn on the boiler to make sure it is working properly. Any controls or settings that were changed during the service will be put back to the customer’s settings.

How long does a boiler service take?

The length of a boiler service typically lasts between 30 and 60 minutes, depending on the type of boiler, brand, and model. If the engineer finds a fault that can be fixed there and then, the length of the service will take longer.

When you book a boiler service, you will be able to arrange a date and time that suits you for the service to be carried out.

When should I have my boiler serviced?

If your boiler service is due soon, then it is time to book a service. You should also book a boiler service if any following apply:

• You have to reset your boiler often


• You have to keep adding water to the central heating system to increase the boiler pressure


• The pilot light often goes out


• Hot water temperature fluctuates when in use


• There are signs of stains or smoke marks on or around the boiler


• The boiler flame is yellow


• The boiler is making unusual sounds


• An unusual odour is coming from the boiler

The above are just some of the signs that your boiler needs servicing. If you are experiencing any signs of a fault with your boiler, you should get it serviced to ensure it is safe to operate.