Getting the best boiler service


Getting the best boiler service

by Matthew Knight

A faulty or badly maintained boiler can be extremely dangerous and can even kill. We went undercover to see how well engineers serviced our faulty boiler - and were shocked by the results. 

Put us to the test

Our Test Labs compare features and prices on a range of products. Try Which? to unlock our reviews. You'll instantly be able to compare our test scores, so you can make sure you don't get stuck with a Don't Buy.

  • Get the Which? verdict from our independent experts
  • Weigh up the pros and cons in an instant
  • Go to town on the details with our full review
  • Read our member reviews to see what they think
  • Is it a Don’t Buy? It could be a dud, and a costly one too
  • Best Buy
  • 370 Boilers available

Looking for a new boiler? Discover which are the most reliable by checking out our boiler reviews.

Can you trust your boiler servicing engineer? 

Our hidden cameras revealed a number of engineers failing to meet the minimum legal requirements for a boiler service and making dangerous mistakes.

We secretly recorded 10 engineers servicing a boiler. Five were from major brands and five were independents. The results were shocking:

  • eight out of ten failed to meet the minimum legal requirements
  • six did not fix the gas pressure, which we had deliberately set too high
  • two did not take the case off the boiler. A third engineer only took it off for just 13 seconds – he spent longer drinking his tea.

We also exposed engineers making potentially dangerous mistakes. These included not checking the boiler case seal for leaks, not checking the flue properly, letting unburnt gas hiss out into the room and – in two instances – lying about safety checks.

Free boiler service checklist

You can download our free boiler servicing checklist - this shows you the key things you should expect to have done during a full boiler service.

You should get your boiler serviced every year. Make sure the engineer is Gas Safe registered. Someone who’s been trained is likely to do a better job than someone working illegally. You can arrange an annual service through a heating engineer you know, it shoulf cost about £70, alternatively you can get boiler cover through a plan like Homecare, that includes a boiler service, but this costs over £200.

Ask what will be included in the boiler service and make a note. 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.

It's also worth getting a carbon monoxide detector.

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

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

Boiler servicing results firm by firm

British Gas and Corgi HomePlan did the best in our investigation.

The Home Energy Services engineer failed to do all the legal checks and lied about what he had done on the paperwork.

The HomeServe engineer did not check the operating pressure of the boiler, which could have led to a build up of soot and the production of carbon monoxide.

And the SSE engineer did not take the case off the boiler.

We also looked at five independent firms. All failed to do all the legal checks and none picked up the dangerously high operating pressure.  

What now for boiler servicing?

We’ve shared our findings with the Gas Safe Register, which inspects gas work.

A spokesman said: 'Our experts inspect around 30,000 gas jobs every year, and if there are any instances where we find that an engineer is not working safely, we take appropriate action to remedy this.

'Following Which?’s claims, we are looking into the registered businesses to inspect their gas work.'

We also shared our results with the firms. In statements, they all said safety was their priority and wanted to investigate further. Home Energy Services, HomeServe and SSE all said they had re-briefed engineers on safety.

British Gas said: 'We were very concerned to hear the account from Which?… We understand the information will be passed to the Gas Safe Register, so we’ll discuss this in detail with them. We take safety extremely seriously and will always ensure any lessons are learned and our high standards are maintained at all times.'

Corgi HomePlan said: "Every gas engineer in our 5,000 strong network is independently evaluated and approved by the legal regulator, Gas Safe Register. We service hundreds of thousands of boilers every year safely.'

Home Energy Services said: 'All of our engineers are fully qualified and Gas Safe registered and our standard procedures include regular audits… We have informed Gas Safe and the Health and Safety Executive of the report.'

HomeServe said: 'If this one allegation is correct, then we are horrified. We do not compromise on gas safety – it is fundamental to what we do – and that is why we choose carefully, and audit rigorously and regularly, the professional gas contractors we work with.'

SSE said: 'We take this incident extremely seriously.  Engineers must abide by all gas safety regulations and SSE has very strict rules… Any evidence of an employee breaking these rules would result in disciplinary action… We have reviewed our company practices.'

Now we are calling for better checks on incompetent engineers.

Paying for boiler servicing

You'll probably save money if you pay for services and repairs as you go along, rather than take out a boiler servicing contract. Our research shows that Which? members paid an average of £70 for their boiler service.

With a boiler servicing contract, you pay a monthly fee that also covers repairs. However, our analysis shows that for more than nine out of 10 Which? members this was more expensive than paying for one-offs. 

The majority of Which? members who have a contract say they pay for peace of mind. If this sounds like you, then see our review of boiler servicing contracts to find the best boiler cover policy for you. 

Before paying for repairs, it's worth checking if 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.

Some home insurance 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 insurance cover is usually much less than getting a breakdown contract, but you don't get the same benefits.