Most reliable gas and oil boiler brands

In our 2023 boiler survey, we asked 10,018 people about their central heating, how satisfied they were with the boiler they own and whether it's suffered any faults or breakdowns. Of these 7,561 have gas boilers and 881 have oil boilers.

From their responses, we work out which brands have the happiest owners and the lowest fault rates.

But this only makes up part of a boiler's overall score. We also asked 198 heating engineers from Which? Trusted Traders what they think of each manufacturer, including how well a brand's boilers are built, how easy they are to fix and service, and how easy it is to get spare parts. 

Some engineers are incentivised by brands to recommend their products. We filter out any responses from these engineers, and only use feedback from those with no commercial affiliation with particular brands — so you can be confident our engineer recommendations are unbiased and reliable.

We combine the engineers' scores with the brand's customer and reliability scores to reveal the best boiler brands.

We've collated the results in the tables below.

Make changes for the planet and your pocket. Sign up for our Sustainability newsletter, it's free monthly

Gas boiler brands rated

Vaillant and Worcester Bosch got the highest customer scores in our survey, but which were ranked most highly by engineers and which came top of our table overall?

Which? members should log in now to unlock the scores in the table. If you're not already a member, try Which? to unlock our boiler research and all our online reviews.  

What are the different types of boiler? - find out if a combi, heat-only or system boiler is the best boiler for your home.

Oil boiler brands rated

Firebird and Worcester Bosch earned customer scores of five stars and three stars respectively, showing that their owners are very pleased. But do boiler engineers agree with them and how reliable will the boilers prove once installed?

Firebird oil boiler engineer and reliability scores

Owners rate Firebird oil boilers highly, but do the engineers that install, service and repair them agree? Plus, how likely are they to need a repair?

The Which? boiler survey reveals all you need to know about this popular brand. 

Worcester Bosch oil boiler engineer and reliability scores

Owners of Worcester Bosch oil boilers rate them highly, but what do the heating engineers that service them think of how well they're built, how easy they are to repair and how long they last?

Sign up to Which? to see the full results and find which are the best.

The cost of a new boiler will also include system cleaning and labour costs. 

Read our guide how much does a new boiler cost? to find out how much you should expect to spend.

Best boiler brands according to heating engineers

We don't just rate boiler brands for reliability and how satisfied customers are, we also gather the views of Which? Trusted Trader heating engineers. We ask them to rate boiler brands on various criteria, so you know if a brand makes boilers that are reliable, easy to fix and are well built. 

How boiler scores are calculated

In June 2023, we surveyed 10,018 members of the public who bought a boiler in the past six years, and asked them about the boilers they own.  

• Reliability score - based on whether people who own a boiler have had to have it repaired. The age of the boiler when the fault occurred and the total number of faults are also taken into account. 
• Brand customer satisfaction score - based on how satisfied customers of each brand are with their boiler, and how likely they would be to recommend it to a friend.

In June 2023, we also asked 198 Which? Trusted Trader heating engineers who work with boilers every day to rate the different  brands. They told us their views on:

• The availability of parts and spares;
• How easy it is to fix a common fault (heat exchanger) on the brand's boilers;
• How easy it is to carry out a service on the brand's boilers;
• The build quality of a brand's boilers;
• The likelihood of them recommending the brand to a customer.

Some engineers are incentivised by brands to recommend their products; we filter out these responses.

The overall score for each brand is calculated by combining the reliability, customer and engineers' scores.

How we assess boilers - read on to find out more about how we assess boiler brands.

Which? Trusted Trader boiler installations

If you're ready to get a new boiler installed, use Which? Trusted Traders to find a reliable boiler installer near you.

Alternatively, head to our guide to buying the best boiler.