Boiler brands rated Best and worst gas boiler brands

To help you choose a new boiler, we got the lowdown on popular condensing boiler brands by asking 10,358 owners – all Which? members – about their experiences of owning their boilers.

Best and worst gas boiler satisfaction scores

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 84%, while the worst gets only 28%. 

Two brands stand out for having the highest customer satisfaction scores and one is worse than average. 

Which? members can log in to view full scores in our boiler reliability 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
AristonSubscriber only content
BaxiSubscriber only content
British GasSubscriber only content
FerroliSubscriber only content
Glow-wormSubscriber only content
HalsteadSubscriber only content
IdealSubscriber only content
KestonSubscriber only content
MainSubscriber only content
PottertonSubscriber only content
RemehaSubscriber only content
VaillantSubscriber only content
ViessmannSubscriber only content
WorcesterSubscriber only content

Table notes

The average Which? customer score is 74%, based on 5,048 responses.

Respondents for each brand are: Alpha (73); Ariston (32); Baxi (361); British Gas (231); Ferroli (43); Glow-worm (446); Ideal (312); Halstead (43); Main (40); Potterton (291); Remeha (39); Vaillant (903); Viessmann (103); Worcester (1,911)

Gas boiler reliability

The Which? reliability score is based on the proportion of boilers that have had repairs, adjusted by age to ensure that all brands are compared on an equal basis. 

We need at least 50 responses per brand to calculate a reliability score. 

Gas boilers Which? reliability index
BaxiSubscriber only contentSubscriber only content
British GasSubscriber only contentSubscriber only content
Glow-wormSubscriber only contentSubscriber only content
IdealSubscriber only contentSubscriber only content
PottertonSubscriber only contentSubscriber only content
VaillantSubscriber only contentSubscriber only content
ViessmannSubscriber only contentSubscriber only content
WorcesterSubscriber only contentSubscriber only content

Table notes

The average brand reliability score is 74%, based on 3,846 responses. Respondents for each brand are: Baxi (278); British Gas (182); Glow-worm (332); Ideal (206); Potterton (187); Vaillant (779); Worcester (1,580).

How we calculate boiler brand customer scores

In June 2013, we asked about the gas and oil boilers Which? connect online panel members had installed since April 2005. 

We asked Which? members about their brand of gas or oil condensing boiler, and to tell us about breakdowns, problems and annoyances with their gas 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.

Avoid expensive boiler problems

To help you avoid costly repair bills Which? has plenty of tips on keeping your boiler in working order and how to find the best boiler breakdown cover and servicing contracts.

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