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Worcester Bosch vs Viessmann Boilers: Which is best?

Worcester Bosch or Viessmann? It's the burning question on every (savvy) boiler buyer's lips. Ruthless German engineering, or belting boilers from a brand as big as Bosch? Here, we drill down in to the positives, the negatives and give our verdict.

Are you sat there, like everybody, in lockdown, pondering the purchase of a boiler replacement from one of the leading brands, but aren’t quite sure which to choose?

Worcester Bosch has been the leading UK boiler brand for decades (that's multiple 10 years), yet, in recent times Viessmann boilers have also established themselves as a top brand. Touché.

Viessmann are you ready?

Worcester Bosch are you ready?

Check out the latest deals on Worcester and Viessmann boilers here

Worcester Bosch vs Viessmann

Worcester Bosch Boilers Review 

Worcester Bosch Boilers Logo

Founded in the UK back in swinging 1962, Worcester Bosch have been a big name in the British boiler industry for decades, renowned for their high-quality build and excellent aftercare. 

So I was just sat there, minding my own business, I turn around, and out of nowhere.... BOSCH!

Presently, the Greenstar range is Worcester’s most popular selection of combi boilers, offering high efficiency, a range of power outputs and dimensions, with the CDi compact being small enough for many standard kitchen cupboards. Neat.

Some of the brands other popular models include the 2000 and 8000, you can read our full reviews of them:

Why Choose Worcester Bosch? 

Worcester Bosch is arguably the best-known brand in the UK and highly regarded among gas installers and consumers. 


Want an exact price on a new boiler? Use our boiler quote calculator (no personal details needed).

But why? What are the main advantages of this brand? Let’s slither into the stats...

Which? Best Buy Award Winner for 10 Consecutive Years 

The Consumer Association’s Which? Award is well respected by consumers and within the industry for their unbiased surveys, in particular the annual best boiler survey. 

Worcester Bosch Which Best Buy

Worcester Bosch has been a Which? Best Buy award winner for 10 years in a row, based on the feedback from over 12,000 boilers and over 100 gas boiler installers. Providing the views of the everyday user and professional opinion.  

Combined, the survey considers and provides an aggregated score based on the following: 

  • Reliability score
  • Customer score
  • Engineer recommendation
  • Build quality
  • Availability of parts
  • Ease of fixing faults
  • Ease of servicing

No other organisation surveys and collects so much data about boilers, so as you can appreciate, the results are considered to be reliable and trustworthy by many consumers and industry insiders. 

Curious to know which boiler brand performed worst? Find out in our report of the worst boilers

So, what did this year’s Which? survey results show? 

Worcester Bosch was awarded full marks for their build quality and availability of parts, two very important factors for any boiler user. 

The Worcester Bosch 10-Year Guarantee 

Worcester Bosch 10 Year Guarantee

Worcester Bosch is unique in that they do not simply offer a traditional warranty, but a no quibble guarantee. 

What’s the difference? Is it just a marketing tactic? 

A guarantee is superior to a warranty since it’s an agreement from the manufacturer that they will attend to your property and repair or replace your boiler as soon as possible. 

A conventional warranty (offered by most other brands) is a contract to investigate the issue, but not an unconditional agreement to repair the boiler free of charge.  

When purchased via Heatable, all Worcester Bosch boilers in the Greenstar Range come with a 10-year long guarantee. 

CORGI’s Domestic Heating Product of the Year 

Corgi Product Of The YearWorcester Bosch’s Greenstar Range is the latest offering from the leading boiler manufacturer.

The range is the brands highest efficiency boiling to date, being modern A-rated boilers, they can help you save an energy and money on your heating bills. 

The quality and efficiency of the Greenstar Range is exactly why it was awarded with CORGI’s domestic heating product of the year for multiple consecutive years. 

Worcester Bosch Trustpilot Reviews 

Worcester Bosch TrustPilot

Awards from third party consumer organisations like which are highly credible, but nothing really comes close to the honesty and reviews of everyday users of the product. 

Fortunately, Worcester Bosch has some of the best customer reviews on the Trustpilot platform and far better than any other condensing boiler manufacturer at all. 

Worcester Bosch has gained an incredible number of user reviews. As of November 2020, nearly 20,000 customers left a review.

Worcester Bosch Reviews

The average rating of these reviews was 4.7 out of 5 stars, quite amazing for a brand selling in such large volumes. A testament to the quality of their products and excellent customer service. 

Is your current Worcester Bosch boiler experiencing problems? Check our Worcester Bosch Boiler Faults guide for common issues and potential fixes. 

You can check the latest deals on Worcester Bosch boilers here, and see how the brand compared to another market leader in our Worcester Bosch vs Vaillant Boilers post. 

Notable Features of Worcester Bosch Boilers: 

So, what do the actual boilers offer in terms of features? Here are some of the best: 

  • Installed with the condenseSure siphon, offering boiler frost protection
  • A-rated boilers - efficiency rating of up to 99.5% when operating at 30% capacity
  • CDi compact ideal for smaller spaces
  • Built-in keyless filling link making it easy to refill your system
  • Low energy pump limits electricity usage
  • 10-year guarantee when purchased through Heatable
  • Excellent customer service and aftercare

Worcester Bosch Combi Boilers  

Worcester Bosch offer many different types of boilers, but their most popular combi boilers are those from the Greenstar Range, which include the following models: 

Model Available kW's Price
Worcester Bosch Greenstar i 25, 30
Worcester Bosch 2000 25, 30
Worcester Bosch 8000 30, 35, 40, 45, 50
Worcester Bosch CDi Compact 28, 32, 36
Worcester Bosch Si Compact 25, 30

Check the latest deals on the above models here

Learn all about combi boilers in our what is a combi boiler guide and see how Worcester Bosch fared against Baxi in our Worcester Bosch vs Baxi comparison. 

Viessmann Boilers Review 

Viessmann Boilers Review

Founded in 1917 and famous for their iconic German engineering and high-quality build, Viessmann have been manufacturing heating products for well over 100 years. 

The Viessmann Vitodens is the brands best-selling combi boiler, offering the perfect mix of energy efficiency, reliability, and technical brilliance. 

Why Choose Viessmann? 

Viessmann is a relatively new boiler brand in the UK market, but due to their high quality and technical specifications, they have soon become one of the most well respected. 

So, what are the main selling points of this boiler manufacturer? 

Which? Annual Boiler Survey Performance 

Viessmann Which? Best BuyAlthough Viessmann are no longer a Which? Best Buy award winner, they have been in the recent years (for 3 consecutive years) and were referred to as a “very smart choice” by the respected consumer association. 

In addition, in the most recent Which? Annual Boiler Survey they performed extremely well. They received a top score i.e. 5 out of 5 for the following: 

  • Reliability
  • Customer Score
  • Engineer Recommendation
  • Build Quality

10-Year Warranty on Parts & Labour 

Your boiler is arguably one of the most complex and used pieces of engineering in your home and it is something we all rely on and take for granted. 

So, when your heating and hot water supply are negatively affected, it can be extremely disruptive and cause discomfort for the whole family. 


Want an exact price on a new boiler? Use our boiler quote calculator (your fixed price will appear on screen).

You want the peace of mind that your boiler will be repaired and fast and that is why a warranty is so important. 

Thankfully, every Viessmann boiler fitted through Heatable comes with a 10-year parts & labour warranty as standard. Not quite as good as Worcester Bosch’s guarantee, but still, it's pretty impressive. 

Viessmann Trustpilot Reviews 

What do Viessmann customers think of their boiler? Did their customer services and aftercare perform well? 

he best place to find out is by checking what they have to say on the third-party review platform Trustpilot. 

Viessmann TrustPilot Reviews

Viessmann, like Worcester Bosch have some incredible 5-star customer reviews. As of November 2020, over 1,000 customers left a review. 

The average rating of these reviews was 4.6 out of 5 stars, which reflects the brands performance in the UK to date. 

Viessmann Boilers TrustPilot Reviews

Notable Features of Viessmann Boilers: 

  • Built-in shock arrestors – to help limit boiler noises
  • Combined Pressure Release Valve (PRV) & condensate pipe – less pipework, more aesthetically pleasing
  • Offer full size and compact boilers
  • Weather compensation - cleverly compares the outside temperature to the ambient temperature in your home and adjusts your heating accordingly
  • Compatible with smart technology e.g. Nest Smart thermostats
  • Stainless Steel Inox Radial heat exchanger – more durable and last longer than the typical “aluminium” variety
  • A-rated boilers - efficiency rating of up to 99.5% when operating at 30% capacity
  • 10-year warranty when purchased through Heatable

Viessmann Combi Boilers

Viessmann offer a range of different boilers, there most popular combi boilers are as follows:

Model Available kW's Price
Viessmann Vitodens 050-W 29, 30, 25
Viessmann Vitodens 100-W 26, 30, 35
Viessmann Vitodens 200-W 26, 30, 35


Worcester Bosch vs Viessmann Boilers 

Who knows.

Both Worcester Bosch and Viessmann share some unique and similar significant advantages and, in many ways, each offer reliability, value and a superb choice for a variety of different hot water demands.

It's all down to what you want.

If you want the safety net and peace of mind that a HUGE brand offers, go for the Worcester Bosch.

Check latest deals on Worcester Bosch boilers here

If you aren't fussed on a brand name, and would rather a technically (German!) better-built boiler, go for the Viessmann (Vitodens 100, or 200 - the 050 is made in Turkey).

Check the latest deals on Viessman here

However, if we were really pushed to choose between the two, we recommend Worcester Bosch (just). Why? 

  • Which Best Buy Award winner for 10 consecutive years
  • A 10-Year Guarantee not just a “warranty”
  • Readily available parts in the UK

Looking to buy a Worcester Bosch, or a Viessmann boiler?

Order with Heatable, and we could be fitting your new boiler tomorrow.

Why choose Heatable? 

  • Gas Safe installation within 24 hours.
  • Thousands of happy customers – an average score of 4.9 on Trustpilot (that’s better than the market leader). 
  • Price match guarantee – if you find a cheaper quote, we will match (must be like for like).  
  • Multiple payment options - interest free available. 
  • 10 year guarantee. 
  • Fixed price guarantee – no hidden costs. 
  • Save your quote until later. 

Use this clickable form to get a fixed price on the screen instantly.

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Heatable is registered in England and Wales No. 08804726 (VAT No. GB205805920 ). Trading address is 1 Station Road, Great Sankey, Warrington, Cheshire, WA5 1RH. Heatable acts as a credit broker (not as a lender) and offers credit products through a panel of lenders. Heatable is authorised and regulated by the Financial Conduct Authority (reference no. 805259).

[1] Price based on a like for like combi swap in a 2 bed, 1 bathroom terraced home with a standard flue

[*] Installation dates are subject to installer availability

[ยน] only available on combi boiler installations

Financial Support: If you are in receipt of certain benefits, you may be entitled to claim a free boiler grant.