Worcester Bosch
Greenstar 2000 Combi
Customer score
Updated: 29 Dec 2021
Best gas and oil boiler brands rated
Discover the best boiler brands: which are most reliable and which are likely to let you down? Make sure you invest in a quality boiler brand.
In our annual boiler survey, we asked 8,001 boiler owners about the brand they own, how satisfied they are with it and whether their boiler has suffered any faults or breakdowns.
From this we generate a brand's customer and reliability scores. The boiler brands their owners love and that don't break down, easily get the top scores.
But this only makes up part of a boiler's overall score. Heating engineers work with boilers day in, day out and are in the best position to give valuable insights on a brand's build quality, how easy it is to fix and service, and how easy it is to get spare parts for your boiler.
We asked 153 trusted boiler engineers from Which? Trusted Traders what they think of each manufacturer.
Some engineers are incentivised by brands to recommend their products. We filter out these responses - so you can be confident our engineer recommendation is unbiased and reliable.
We combine the engineers' scores with the brand's customer and reliability scores to 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.
There's a huge difference in overall score between the best boiler brands and the worst. Join Which? to discover the best.
Read our boiler reviews to find the best brands, or check our expert guide on how to buy the best boiler if you need help deciding on the type and size of boiler you need.
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.
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.
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.
| Brand | Overall score | Reliability score 1 | Brand customer score 1 | Brand engineer overall score 2 | Typical price for a 30kW Combi 3 |
|---|---|---|---|---|---|
| Grant | £2,530 - £3,150 | ||||
| Worcester Bosch | £2,330 - £2,440 | ||||
| Table last updated 2 December 2021 Table notes: Reliability and brand customer score based on responses in May-June 2021 from 8,001 members of the public who've bought a boiler in the past six years. Brand engineer overall score based on responses from 153 Which? Trusted Trader heating engineers in June 2021. Typical price range based on low and high prices for a standard 30kW combi boiler across the brand's range. A 30kW boiler is suitable for most medium-sized homes. Price doesn't include installation costs. | |||||
What are the different types of boiler? - find out if a combi, heat-only or system boiler is the best boiler for your home.
Best boiler brands according to heating engineers
Best gas boilers according to 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.
Best oil boilers according to heating engineers
| Brand | Brand engineer overall score | Availability of spare parts | Ease of fixing a common fault | Ease of servicing | Build quality | Unbiased engineer recommendation |
|---|---|---|---|---|---|---|
| Grant | ||||||
| Worcester Bosch | n/a | n/a | ||||
| Table last updated 2 December 2021 Table notes: based on responses from 153 Which? Trusted Trader heating engineers in June 2021. n/a - not enough responses to be included in the brand engineer overall score. | ||||||
A great service will keep your boiler in tip top shape for longer - read our guide on getting the best boiler service.
How the boiler scores are calculated
In May and June 2021, we surveyed 8,001 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 boilers have ever had to have it repaired since they bought it. The age of the boiler when the fault occurred, and the total number of faults is 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 2021, we asked 153 Which? Trusted Trader heating engineers who work with boilers every single day to rate the different boiler 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 brand score for each boiler brand is calculated by combining the reliability score, customer score and the 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 are ready to install a new boiler in your home, use Which? Trusted Traders to find a reliable boiler installer near you.
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