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What Does a Boiler Service Involve?

Boiler Service

An annual boiler service keeps it working safely and running efficiently.

During a boiler service, an engineer will perform a few checks on your central heating system. But what exactly does it involve? We’ve put this guide together so that you know why your boiler needs servicing and what will happen during that service.

We can also put you in touch with up to 3 qualified and trustworthy engineers in your area. Each will give you a free quote for your boiler service so you can compare prices and choose the best.

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Why a boiler service is important

Here are just a few reasons why you should get your boiler serviced each year:


A boiler service gives the engineer the opportunity to identify safety issues such as a carbon monoxide leak. Carbon monoxide is an odourless and colourless gas which can quickly cause brain damage and, in some cases, death. If you're concerned that your boiler may not be working correctly, for example the flame is orange rather than blue, you should get in touch with a Gas Safe engineer even if your annual service is not yet due.

Keep heating bills low

As a boiler ages it can become less efficient which means it needs to use more fuel to heat your home which will cost you more money. An annual service will ensure all the components are in the best possible condition and deliver a higher level of efficiency for longer.

Prevent breakdowns

It could be easy to put off getting your boiler serviced in the hope of saving yourself a bit of money, but in the long run, a boiler service will help keep your energy bills down and also spot a potential fault before it happens, saving you from a boiler breakdown and a hefty repair bill.


Your boiler will usually include a manufacturer's warranty of between 1 – 15 years which means any faults that develop in that time will be repaired free of charge. However, this warranty is only valid as long as you get the boiler serviced by a Gas Safe engineer every year.

What happens during a boiler service?

Before we list what happens during a service, it’s important to ensure that the engineer is qualified to carry out the work. If you have a gas boiler then the engineer must by authorised and regulated by the Gas Safe register, while an oil boiler should be serviced by an OFTEC engineer. Ask to check their ID card before they start work on your boiler.

Here are some of the practices your engineer may carry out during their visit:

  • Visual inspection – your engineer will check that the boiler still meets current standards and requirements and look for any corrosion or leaks. They will also visually check the flame in your boiler.
  • Removal of the boiler casing - they will then check the components to ensure everything is working correctly and then clean the inside of the boiler. These checks should include the heat exchanger, burner, main injector and spark probe.
  • Flue check - the engineer will ensure there are no obstructions in the flue terminals and that the flue is safely fitted.
  • Gas pressure check - this will ensure your boiler is working at the correct pressure.
  • Boiler fired up - this allows the engineer to check for any working faults.

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To find out more about boiler services for your make of boiler simply choose your brand from the below table:

Alpha Service Grant Service Ravenheat Service
Ariston Service Ideal Service Vaillant Service
ATAG Service Intergas Service Viessmann Service
Baxi Service Johnson & Starley Service Vokera Service
Biasi Service Keston Service Warmflow Service
Ferroli Service Main Service Worcester Bosch Service
Firebird Service Mistral Service Zanussi Service
Glow-worm Service Potterton Service

How long does a boiler service take?

A boiler service should last at least 30 minutes but the time will vary depending on the brand and model. Afterwards, the engineer will likely give you a service report, explaining what they’ve done. Don't be afraid to ask them any questions, you might have regarding the boiler service, they will likely be very happy to explain things and advise you appropriately. 

When should I service my boiler?

As we’ve mentioned, any boiler should be serviced annually, this not only ensures that the heating system is running safely and efficiently but is also a requirement to keep the warranty valid in many cases.

The best time of year is during the summer, when there’s less reliance on your boiler. This way, you know that your boiler is ready to heat your home come the cold winter months. You’ll also find that engineers aren’t as busy at this time of year.

If you’re concerned that your boiler may not be working correctly, it is advisable to get in touch with a registered and qualified engineer even if your annual service is not yet due as there could be a safety issue.

How much does a boiler service cost?

The cost of a full boiler service will vary depending on the type of unit you have and where you live. Getting a standard efficiency boiler serviced will cost from £50 to £80, with a high-efficiency condensing boiler service costing around £80 to £160. If you live in London, then you are likely to be charged more than those living in rural areas.

You could potentially save money by getting your boiler serviced during the summer when engineers aren’t as busy. This will also give you the peace of mind that your boiler is ready to heat your home and provide hot water when the cold winter comes around.

Boiler cover & service plans

If your boiler is no longer covered by a manufacturer’s warranty you may want to consider a boiler cover plan which includes servicing. For a monthly fee, the cost of your annual service is taken care of and you’ll have peace of mind that should anything go wrong you won’t be facing an unexpected repair bill. However, it’s worth noting that over a year your monthly fees are likely to add up to more than the cost of a service.

Gas boiler services

A gas boiler service has to be carried out by a Gas Safe registered engineer and is essential to not only keep the boiler running efficiently but also ensure that there isn’t a risk of carbon monoxide leaking into the home. Find out more with our guide to getting a gas boiler service.

Oil boiler services

Oil boilers should also be serviced annually to ensure that they’re running safely and efficiently and must be carried out by an OFTEC engineer. Find out what’s involved and how much it is likely to cost with our guide to getting an oil boiler service.

Comparing quotes from several engineers will help you find the best deal possible. Complete one of our simple online form and you’ll get free quotes from up to 3 trusted engineers in your local area, giving you the ability to pick the best deal for you.

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Becky Mckay

About the author

Becky Mckay

Becky is one of our home heating and renewable energy experts and has a wealth of experience writing about the world of heating.

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