Boiler servicing contracts: Getting a good boiler service Boiler service

A faulty boiler can be extremely dangerous, increasing the risk of carbon monoxide poisoning. It's therefore best to get your boiler serviced every year to make sure it's working properly.

To ensure you're getting a good boiler service it helps to know what to expect, so we've created this video to explain. It's presented by Which? Local recommended boiler servicing company Fuller Heating. 

Finding a local boiler engineer

Which? Local is a recommendation site exclusively for Which? Members and has hundreds of recommended boiler engineers across the UK.

The boiler in the video is a combination boiler. If you have a conventional or older boiler the service may look different and, as all boilers are different, services will vary. Whoever you choose to do the work, check they're on the Gas Safe Register.

Video: what should be included in a boiler service


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Annual boiler service checklist

Try to arrange your service for the summer months, before the traditionally busy autumn season, when people start putting the heating on and there are more breakdowns.

The checklist below shows the key things you should expect to have done during a full boiler service.


  • A visual check to ensure your boiler still meets current standards

  • Boiler fired to identify any working faults

  • Boiler casing removed to check all main boiler components (burner, heat exchanger, main injector, spark/sensor probe).

  • Checks to ensure flue terminals are unobstructed and internal flue components are sealed properly

  • Gas valve adjusted to check that burner is combusting efficiently and properly (normally using a flue gas analyser).

  • Inside casing surfaces cleaned

  • Boiler parts cleaned if necessary

  • Gas tightness test conducted to ensure no leaks

  • Boiler casing put back on - check that properly sealed

  • You should receive a service report that shows everything the engineer has done to maintain your boiler

Not all boilers are the same

Though the above checklist should stand you in good stead for most boilers, bear in mind that not all boilers are like the one serviced in our video.

For most older conventional systems, for example, the following would apply:

  • The pump and expansion vessel would not be contained within a conventional boiler. In most cases they would be near the hot water cylinder.
  • Parts such as the heat exchanger, burner and fan would need to be dismantled and checked. This would not normally be necessary for the modern boiler in the video, unless the flue gas analysis suggests that there is a problem.

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