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Getting the best boiler service

Find out how you can get the best boiler service to keep your boiler in tip-top condition
Sam Morris
Boiler engineer 451097

An annual boiler service is essential for keeping your boiler running smoothly and safely.

Our 2021 boiler reliability survey of 8,001 boiler owners found only around three in 10 boilers that are serviced annually have needed a repair in their first six years. This doubles to around six in 10 boilers if the boiler is only serviced every two to five years.

So, spending a bit of money on a boiler service could potentially spare you a huge repair cost in the future, as well as giving you peace of mind.

Read on to find out what you can do to ensure you get the best boiler service. We'll also tell you how much you should expect to pay for a boiler service so you don't get overcharged.

Find out more about boiler cover or arrange your boiler service today with a reliable local engineer through Which? Trusted Traders

How much does a boiler service cost?

There are two types of boiler service schemes: an annual boiler cover package or a one-off service.

A one-off service should cost anywhere from £60 to £100 for a gas boiler, and a little less on average for an electric boiler. Our 2021 survey of 153 Which? Trusted Traders found £86 to be the average price they would charge for a one-off service. 

A boiler cover package typically costs £200 to £300 a year and should include an annual service and cover repair costs. A 2021 survey of 1,730 Which? members found the average member pays £297 per year for a boiler cover package.  

Which is cheaper: one-off service or boiler cover?

You'll save money if you pay for services and repairs as you go along, rather than take out boiler cover - where you pay a monthly fee that also covers repairs.

Our analysis shows that even if you had to pay for a repair once every two years, you can expect to save about £113 per year by paying for one-off services and repairs, rather than boiler cover.

And if you have a reliable boiler brand that breaks down less frequently than less reliable brands, you could expect that saving to be even bigger.

ScenarioAverage cost per yearCost over 12 years
Pay for boiler cover£297£3,564
Pay for an annual boiler service£86£1,032
Pay for an annual boiler service, plus six repairs over the 12 years£184£2,208
Table notes: Pay for boiler cover average cost per year based on 2021 Which? survey of 1,730 members. Pay for an annual boiler service based on the average price charged for a one-off service according to our 2021 survey of 153 Which? Trusted Traders. Pay for an annual boiler service, plus six repairs over the 12 years based on an average number of boiler repairs of three, according to our 2021 Which? survey of 8,001 people who bought a boiler within the past six years. Average cost per year based on the average price paid for a boiler repair of £196 according to our 2021 Which? survey of 8,001 people who bought a boiler in the past six years: £86 + (6 x £196)/12 = £184.

Some home insurance companies also gives you cover for boiler breakdowns, either as standard or as an optional extra, so it's worth checking if you already have this. The cost of adding breakdown cover to an insurance policy is usually much less than getting a breakdown contract, but you don't get the same benefits.

Find out what you should expect to pay for a repair in our common boiler problems and repairs guide

Boiler service checklist

There is a file available for download. (pdf39 KB). This file is available for download at .

It's important that you get your money's worth from a service, after all the purpose of it is to prevent your boiler breaking and costing you more in the long run.

Here's what should take place as part of a boiler service:

  • A visual check of the boiler and flame, if possible
  • Checks on the flue (externally and internally)
  • Checking the operating pressure and/or heat input
  • Checking safety devices
  • Check case seals for an effective seal
  • Boiler casing removed to check all main boiler components (burner, heat exchanger, main injector, spark/sensor probe)
  • Boiler fired safely to identify any working faults
  • Boiler parts cleaned, if necessary
  • A service report showing everything the engineer has done

You should get your boiler serviced every year by a Gas Safe registered engineer. You can arrange a service yourself or through a heating engineer – it should cost about £86.1 Alternatively, you can get boiler cover through a plan, such as Homecare, that includes a boiler service, but this can cost more than £200.

We would recommend getting your boiler serviced by a Which? Trusted Trader. You can use our Trusted Trader search tool below to find reliable boiler engineers in your area

Benchmark app

Remembering to get your boiler serviced can be a pain but a new app from Benchmark (available on iOS and Android) will make boiler servicing more transparent and easier for homeowners to stay on top of.

Like a car’s service booklet, the Benchmark app acts as a digital record of your boiler’s installation and servicing history.

If your boiler has been installed within the past 12 months and a Digital Benchmark record was created by your installer, it will let you see exactly what has been done during your boilers installation and each service.

The app sends push notifications to alert you when it’s time to get your boiler serviced. All this makes it easy to keep up with regularly servicing your boiler, ensuring it remains in warranty and your heating system performs as efficiently as possible.

Boiler service tips

boiler service
Ask what will be included in the boiler service. Watch the engineer and use our checklist to ensure that they cover the basics. A good boiler service should last at least 30 minutes. If it’s shorter than this, ask why. 

Finally, ask for a written report and check it is accurately filled out. If you have any concerns, contact the Gas Safe Register on 0800 408 5500 or through the Gas Safe Register website.

You should get a carbon monoxide detector to be safe, and from February 2022 onwards you will legally obliged to have one if you live in Scotland.

Before paying for repairs, check whether your boiler is still under its initial warranty. Most new boilers typically come with cover for parts and labour in the first one or two years.

Although the checklist should stand you in good stead for most boilers, bear in mind that not all boilers are the same.

Most older conventional systems, for example, have parts such as the heat exchanger, burner and fan that would need to be dismantled and checked. This is not normally necessary for a modern boiler, unless the flue gas analysis suggests there's a problem. 

If you're getting a replacement boiler, use our new boiler costs guide to see how much you can expect to pay

Boiler servicing customer scores

We also surveyed 1,730 Which? members in 2021 to gather their opinions about the company they'd used most recently for a boiler service. 

There are scores of independent boiler engineers you could use, but we can't gather a large enough sample size to the able to rate them. The table below shows results for the six most popular boiler servicing companies. 

Most were easy to contact, and easy to schedule a service with, which is reassuring. But there were big differences between the best and worst when it came to value for money: the worst brand may surprise you. 

BrandCustomer ScoreEase of contacting companyEase of scheduling a serviceCustomer service by the boiler engineerValue for money
British Gas (1,182)
Corgi (98)
Domestic & General (52)
HomeServe (70)
Worcester Bosch (141)
Vaillant (94)

Table notes: The results are based on an online survey of 7,930 members of the Which? Connect panel conducted in June and July 2021. A dash ‘-’ means not enough responses to include a star rating. Brands are listed in alphabetical order. Sample sizes in brackets (which include people with and without boiler cover). 

Boiler servicing information by firm


The AA is no longer providing quotes for boiler and home cover to new customers. 

If you opted for ‘central heating response plus’ cover with the AA, you'll be entitled to an annual service per membership period. An engineer will do an initial inspection and service within 42 days of taking out the cover and then you'll be contacted when the second service is due.

The service includes:

  • Boiler combustion test
  • Visual inspection of flue route and termination
  • Checking for water leaks, signs of heat stress and mechanical deterioration
  • Checking pipe work and ventilation
  • Carrying out a leak detection check
  • The disassembly and cleaning of key components where they are found to be not performing to the manufacturer’s recommended specification.

The annual service does not include the following:

  • Removal of sludge or hard-water scale from the main heating system
  • Chemical flush.

Length of service: 30 minutes

Cost: The AA is no longer providing quotes for boiler and home cover to new customers.

British Gas Logo

British Gas

British Gas offers a one-off boiler service starting from around £85 or you can sign up to one of four HomeCare cover packages, all of which include an annual service. The cost of both will depend on factors such as water hardness and property type.

Once a deal is agreed and you receive a quote your service will include:

  • Checking your boiler for corrosion and leaks
  • Cleaning its parts as required
  • Removing your boiler casing to check its main components are working
  • Putting the casing back on and make sure it’s properly sealed
  • Checking the gas pressure to make sure it’s at the right level
  • Doing a flue test to check that there are no unsafe emissions coming from your boiler

At the end of the visit, their engineer will leave a checklist with you including all the relevant safety information for your boiler. Neither services cover repairs to your gas boiler.

Cost: Starting from £85 for a one-off service or from around £168 (£60 excess) or £258 (£0 excess) for an annual contract


As part of its Corgi HomePlan cover, they offer basic boiler and central heating system repairs and an annual boiler service with its 'essentials' cover package. A boiler service is also included in more expensive packages, too. The service includes:

  • A visual check of the boiler
  • The boiler being fired safely to identify any working faults
  • A flue gas analysis efficiency test
  • Opening up the boiler and inspecting it, if necessary
  • Checking the flue and ventilation are in accordance with Gas Safety (Installation and Use) regulations
  • Checking and adjusting the system pressure
  • Cleaning the condensate trap
  • Visually checking and bleeding radiators, if necessary
  • A visual check of the hot water cylinder
  • Confirmation in writing that the service has been carried out.

If your boiler is over seven years old when you take out the cover, the monthly premium will increase by up to £2.

Length of service: 45 minutes

Cost: From £156 (£60 excess) or £216 (£0 excess) for an annual contract 

HomeServe Logo


HomeServe offers one-off boiler servicing from around £96. Its service includes:

  • Boiler inspection to make sure it’s working properly
  • Cleaning the parts if needed
  • Checking that all the seals and gaskets are secure
  • Making sure it’s not emitting any unsafe fumes
  • Testing the gas connections and gas pressure
  • Visually checking any other gas appliances.

Appointments are booked in four-hourly windows and can be made via the website. HomeServe doesn’t service or repair Promox, Powermax, Ferroli, Keston or Gledhill boilers.

A free service is also included in the first year when you sign up to one of its boiler cover packages.

Length of service: 45 minutes

Cost: £96 for a one-off service or from £243.96 (£100 excess, £96 in your first year) or £305.16 (£60 excess, £138 in your first year) for an annual contract 

Scottish Power

To receive an annual boiler service with Scottish Power you’ll need to sign up to its 'boiler and service care' cover. Other features in the plan include ongoing maintenance, a 24/7 UK-based helpline and a replacement boiler worth up to £750, if required.

The 'Boiler Insurance' packages do not include an annual service.

Length of service: 38 minutes 

Cost: From £126 (with a £99 call-out fee) or £226.80 (with a £0 call-out fee) for an annual contract


An SSE annual service is a fixed-price of £90, SSE will send out a Gas Safe-registered engineer to service your boiler. If there are repairs needed the engineer can offer you a quote to fix it and you'll be provided with a report at the end.

If anything goes wrong within 21 days of the call-out, an engineer will come out free of charge. If the problem is a result of the service it will also be repaired for free.  

SSE boiler and heating cover is also offered. It includes an annual service. Prices start from £20.45 a month. 

Length of service: One hour 

Cost: £90 for a one-off service, around £245.40 for an annual contract


The cost and length of an independent boiler service will vary depending on the age and model of your boiler, the area in which you live, who carries out the service and the time of year, so always seek a handful of quotes and make sure the engineer is Gas Safe registered. 

A small business will usually provide better service to customers, especially locally, as they rely on word of mouth and recommendations to retain and grow their business. 

A potential issue is that independent traders are often very busy, so may not be able to respond as quickly as big companies. However, most will have several trusted colleagues that they can recommend if they are too busy or are on holiday.

When searching for a gas engineer, you should be looking for somebody that you feel confident with and can call back on a regular basis,. This will build up a trusting relationship for valuable advice. A good local gas engineer should be happy to discuss issues on the phone, whereas a large company is likely to charge for a visit.

Over time, your engineer will become familiar with your boiler, which helps to pre-empt issues before they become major problems.  

Find a Which? Trusted Trader today. You don't have to be a Which? Member to use Which? Trusted Traders. 

Length of service: Between 25 minutes and one hour 

Cost: Between £60 to more than £100 for a one-off service

Which trusted trader banner

Boiler servicing information by firm - prices last checked 14 February 2022. Prices ignore introductory offers, so are representative of what you will be paying annually after these offer periods have expired.