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24 June 2021

Best gas and oil boiler brands rated

Find out which boiler brand is the most reliable and which is likely to let you down during the cold months. We reveal if a Baxi will outlast a Worcester Bosch so you know if you're investing in a quality boiler brand
Matthew Knight
Boiler flame_main 415468

In our annual boiler survey, we asked 7,500 boiler owners about the boiler brand they own, how satisfied they are with it and whether their boiler has suffered any faults or breakdowns. 

We also asked 153 trusted boiler engineers from Which? Trusted Traders what they think of each manufacturer and how likely they are to recommend boilers from the brand.

The results enable us to reveal the best boiler brands and the worst. We've collated the results in the tables below for both gas and oil boiler brands.

You can use our results to discover which brands are the most reliable, have the highest customer score, the best build quality according to boiler engineers, and are the most likely to be recommended by boiler engineers who aren't incentivised to install boilers from that brand. 

There's a huge difference in overall score between the best boiler brands and the worst.

After you've chosen the best brand, make sure you read our guide to five things to know before you buy a new boiler.

Gas boiler brands rated

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.  

Customer score
Engineer recommendation
Overall score

Table notes: Engineer recommendation, build quality, availability of parts and spares and ease of fixing a common fault, quality of technical service and recommendation are based on responses to a survey of 153 Which? Trusted Trader heating engineers that took place in June 2020.

Oil boiler brands rated

The table below reveals the oil boiler brands you can trust. Log in now or join Which? to unlock the tables results.

Customer score
Availability of parts and spares
Overall % score

See our Worcester Bosch boiler reviews and Grant boiler reviews.

Boiler Engineer fixing a boiler

Best boiler brands according to heating engineers

We don't just rate boiler brands for reliability, and how satisfied the brands customers are, we also gather the views of more than 150 Which? Trusted Trader heating engineers

Log in now or join Which? to unlock the tables results, including ratings for build quality, the availability of parts and spares, ease of fixing a common fault, ease of servicing and engineer recommendation.

Availability of parts
Fixing a common fault
Build quality
Ease of servicing
Engineer recommendation

Table notes: In June 2020 we surveyed 153 Which? Trusted Traders on their opinions on different boiler brands.

How the boiler scores are calculated

Updating time for boiler

In May and June 2020, we surveyed 7,500 members of the general public, online, and asked them about the boilers they own.  

  • The reliability score: This is based on whether people who own boilers up to six years old have ever had to have it repaired since they purchased it. The age of the boiler when the fault occurred, and the total number of faults is taken into account. 
  • The customer satisfaction score: This is based on how satisfied customers of each brand are with their boiler, and how likely they would be to recommend it to a friend.

The engineer scores are based on the views of 153 Which? Trusted Trader heating engineers who work with boilers every single day. We surveyed them in June 2020 and they told us their views on; 

  • build quality
  • their likelihood to recommend the brand
  • the availability of parts and spares
  • how easy it is to fix a common fault
  • how easy it is to service.

The overall brand score for each boiler brand is calculated by combining the reliability score, customer score and the engineers' scores. The results are weighted 40% for reliability, 30% for customer score and 30% for the engineers' scores.

If you are ready to install a new boiler in your home, use Which? Trusted Traders to find a reliable boiler installer near you.