Boiler brands rated Best and worst gas boiler brands

After a new boiler or a replacement boiler? To find out which are the best and worst boiler brands, we asked more than 10,000 boiler owners about the brand they own, how satisfied they are with it and if their boiler had suffered faults or breakdown.

The results enable us to recommend to you the best and worst brands of boiler both for reliability and overall customer satisfaction - read on for our verdict and recommendations in the tables below.

Best and worst gas boiler replacement brands revealed

There's a big difference between the best customer satisfaction score and the worst; the top-rated boiler manufacturer has a customer satisfaction score of 89%, while the worst gets only 61%. Three brands stand out for having the highest customer satisfaction scores. 

Which? members can log in now to unlock the scores in our boiler satisfaction league table below. If you're not already a member, sign up to try out full access for one month, for just £1.

Gas boilers Which? customer score
AlphaSubscriber only content
BaxiSubscriber only content
British GasSubscriber only content
Glow WormSubscriber only content
IdealSubscriber only content
Johnson & StarleySubscriber only content
MainSubscriber only content
PottertonSubscriber only content
Rehema AvantaSubscriber only content
VaillantSubscriber only content
ViessmannSubscriber only content
VokeraSubscriber only content
WorcesterSubscriber only content


To find the best individual model of gas boiler for you, go to our full boiler reviews.

Most and least reliable new boiler brands

Below we reveal the most and least reliable boiler brands. Our unique Which? reliability score is based on the proportion of boilers from each brand that have had repairs, adjusted by age to ensure that all brands are compared on an equal basis. 

We only rate those brands that we received 30 responses or more about, to ensure we can assess each brand fairly.

Gas boilers Which? reliability index
AlphaSubscriber only contentSubscriber only content
BaxiSubscriber only contentSubscriber only content
British GasSubscriber only contentSubscriber only content
Glow WormSubscriber only contentSubscriber only content
IdealSubscriber only contentSubscriber only content
MainSubscriber only contentSubscriber only content
PottertonSubscriber only contentSubscriber only content
VaillantSubscriber only contentSubscriber only content
ViessmannSubscriber only contentSubscriber only content
VokeraSubscriber only contentSubscriber only content
WorcesterSubscriber only contentSubscriber only content


How we calculate boiler brand scores

In June 2014 we asked 10,119 people who've had a gas or oil condensing boiler installed since April 2006 about their boiler, using our online consumer panel of Which? members.We asked them to tell us about breakdowns, problems and annoyances with their boiler.

We also asked them to assess how satisfied they were, and how likely they would be to recommend their brand of gas condensing boiler (regardless of their experience of getting the boiler installed). These two questions form the basis of the Which? customer satisfaction score.

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