Viessmann boilers review

Manufacturer Viessmann is most well known for its Vitodens range of residential gas boilers. On this page, we reveal how the brand is rated by its customers.

Our latest boiler survey polled more than 10,000 members of the general public. After crunching the numbers, we found that Viessmann gas boiler owners are fairly content with their models, though not as satisfied as rival brands Worcester Bosch, Vaillant, Ariston and Sime. But our boiler brand customer scores only account for 20% of the overall brand score.

Only Which? members can access our full results and find out how Viessmann boilers stack up against the competition. Log in now or join Which? to access the full results.

Viessmann gas boilers score

Ownership of Viessmann gas boilers is still fairly small in the UK. Most Viessmann gas boiler owners are happy: 83% of them report satisfaction with their boiler, although this is lower than the average satisfaction rate of 87%. 

83% of Viessmann customers were also likely to recommend the brand to someone else. 

While Viessmann's customer score is unlikely to motivate potential buyers to pick the brand over any other, it only makes up 20% of our overall brand score.

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We heard from 198 expert engineers who scored boiler brands on several tests. We asked them to score gas boiler brands on the following:

• The ease of sourcing spare parts 
• How easy it so to change a common component (a heat exchanger)
• The ease of servicing the brand's boilers
• The build quality of the brand's boilers
• The quality of technical support provided by the manufacturer
• Whether or not engineers would recommend the brand to consumers (we filter out incentivised and brand affiliated engineers).

We aggregate all of these scores and use them to create our 'overall engineers' score' which makes up 40% of our total brand score.

Which? members can see how engineers rated Viessmann gas boilers on all of these tests by logging in, while others can sign up to Which? to unlock our full analysis.

Boilers are major purchases that you should only need to make once every 10-20 years. You can keep yours for longer if you get it regularly serviced and if you get faults fixed quickly.

We've asked people who bought a boiler in the past six years about whether it's fault-free. When faults are reported, we measure how serious the fault was, how long it took for the first fault to happen, and we make sure it was fixed by an engineer.

Using this data, Which? members can see which brands produce boilers that are less prone to faults than others.

Subscribe to Which? to see all of the results.

Viessmann boiler costs

Combi boilers

Regular boilers

System boilers

Where to buy Viessmann boilers

It's easy to rush into making a decision, especially if your boiler breaks down in winter, but we recommend getting a couple of quotes from a qualified heating engineer and comparing costs. Our Trusted Trader service can link you up with vetted boiler installers in your area.  

You could also buy a boiler yourself and hire an installer, though make sure you seek expert advice before doing so, to have your current heating system assessed and identify the type of boiler that meets your specific needs. If you buy a boiler without having an installer lined up, you could find yourself struggling to find someone willing to set it up for you. An installer may have access to trade or wholesale prices, and will be able to recommend a model based on a holistic assessment of your home and heating system.

Only a Gas Safe Registered engineer/installer can install a new boiler: it's both dangerous and illegal to do so yourself if you're not qualified.  

Where to buy a boiler – find out what your options are

Are Viessmann boilers efficient?

New boilers must be A-rated, but how efficiently your boiler works in practice depends on several factors, including how you use it and how well it's installed. Use a Which? Trusted Trader for your boiler installation and regular maintenance.