Worcester Bosch vs Viessmann Boilers – which is best? Re April 21, 2021

Worcester Bosch vs Viessmann Boilers – which is best?


If you can afford to buy a new boiler in the ‘premium’ bracket, then there’s a good chance you’re looking at buying a Worcester Bosch boiler or a Viessmann boiler.

There are plenty of great budget boiler choices available if you aren’t looking to spend too much on a new boiler too.

In this article we’re pitting both Worcester Bosch and Viessmann against each other in a no holds barred, fight to the death to decide the ultimate boiler brand (perhaps not to the death, but it’s going to get tasty).

Both companies have an excellent reputation and both manufacture excellent boilers, but which is the best boiler? It’s going to be a close call, but there can be only one victor.

In this article, we will give you a bit of background on both boiler brands and do a direct comparison between the Worcester Bosch Greenstar 8000 Life 35kw Combi Gas Boiler and the Viessmann Vitodens 200-W 35kW Combi Gas Boiler. Two like-for-like 35kW boilers representing the latest technology being sold in the gas combi boiler market.

In terms of what defines the best boiler, we would say it comes down to a few key factors – price, reliability, energy efficiency, and aftercare.

Before we get into the good stuff, there are a few other articles we’ve written that may be of interest to you:

Worcester history

Worcester was formed in 1962 in Worcester, where it imaginatively took its name. It started off as a small engineering works before growing into the biggest boiler manufacturer in the U.K. It was acquired by Robert Bosch Holdings in 1992 to form the Worcester Bosch Group.

Worcester currently holds the Royal Warrant to supply heating to the Royal Family and has won the Which? Best Buy award for their range of boilers for the last ten years. This prestigious award is judged on reliability, build quality, recommendation, and customer score.

For a full timeline of Worcester Bosch’ history click here

Viessmann History

The Viessmann Group is a German manufacturer of heating, industrial, and refrigeration systems headquartered in Allendorf, Germany. (Wikipedia)

Viessmann’s roots go back even further than Worcester’s, starting in 1928, where Johann Viessmann was asked by a local gardener to build a boiler for his greenhouse. Johann, then a locksmith, thought ‘why not’ (they didn’t have Playstations back then).

Viessmann innovated on the iron boilers around at the time and built his using steel which heated up faster and used less fuel. Nice work Johann! Soon, all the gardeners in the village wanted one, and Johann got his model patented and set to work. As you can see from the image below, Johann was all about the work

Since January 2018, the company is led by Martin Viessmann (Chairman of the Executive Board), Maximilian Viessmann (Co-CEO and part-time Bond villain), and Joachim Janssen (Co-CEO). Making Viessmann a family-owned business for four generations, quite a rare thing.

You can find out more about the Viessmann company and the rich history of over 100 years in business yourself, as that could be a blog on its own.

Before we get into comparing the might Worcester Bosch Greenstar 8000 Life against the Viessmann Vitodens 200-W, we should probably mention that we have a Boiler Comparison tool that allows you to compare up to three boiler models or brands at one time. You will be able to compare efficiency ratings, warranty, brand reliability and more with this tool.

On that note, let’s get into this comparison. Let the battle commence! 

Comparison table

WB 8000

Below we compare the Worcester Bosch Greenstar 8000 Life 35kw Combi Gas Boiler and the Viessmann Vitodens 200-W 35kW Combi Gas Boiler. Comparable 35kW boilers from both Worcester and Viessmann and compare key stats to see if we can separate these two boiler powerhouses.

Boiler makeViessmannWorcester Bosch
Boiler modelVitodens 200-WGreenstar 8000 Life
Boiler typeCombiCombi
Fuel typeGasGas
Is CondensingCondensingCondensing
Efficiency Rating94%94%
Band RatingA-RatedA-Rated
LPG CompatibleYesYes
Standard Warranty3 Years5 Years
kW Options35kW35kW
MountingWall MountedWall Mounted
Flow Rate14.3 l/min14.3 l/min
Typical price*£1717.05 (inc VAT)£1313.87 (inc VAT)
ErP ratingA Heat, A WaterA Heat, A Water

Granted, the table above doesn’t do much in terms of separating these two boiler brands, it only goes to show just how close they are in terms of the boilers they can produce. The only key stats that separate them are the price and warranty/guarantee length.

The Worcester Bosch boiler comes in £400 cheaper, which is a pretty big saving. The added 2 years warranty isn’t bad either.

This round goes to Worcester Bosch, landing a swift roundhouse to the face of Viessmann, BOSCH!

vitodens 100-w


Worcester has won the Which? Best Buy award for their range of boilers for a staggering ten consecutive years. This prestigious award is judged on reliability, build quality, recommendation, and customer score.

This survey reaches out to around 10,000 property owners and just over 200 heating engineers each year, asking them what they think of the 11 best boiler brands (depending on the brand they own/install).

Worcester Bosch boilers come out on top from industry side reviews with a Which? brand score of 92% compared to Viessmann boilers brand score of 84%. Worcester lands a cheeky jab to Viessmann’s face there.

Despite getting voted “Most Reliable Boiler Brand”, only 66% of Viessmann customers said they would recommend the brand to a friend, which is quite surprising for a brand with such an excellent reputation.

When it comes to reliability, we can always count on Worcester Bosch to keep their customers in mind. Whilst the UK Government continues to increase the amount of green fuels being introduced, such as bio-methane and hydrogen, Worcester Bosch has ensured that their customers can be confident that their new gas boiler will run for its lifespan.

Martyn Bridges, Director of Technical Communication and Product Management at Worcester Bosch has said that all Worcester Bosch Greenstar condensing gas boilers manufactured since 2000 can accept a hydrogen blend of up to 20%.

Bridges also said that “the fact that Worcester’s boiler can already accept a blend of up to 20% is further evidence why injecting green fuels such as bio-methane and hydrogen into the UK gas grid is a positive step towards the wider implementation of these new, carbon-free fuels”.

Worcester Bosch is involved in multiple trials with hydrogen gas, including one at Keele University. For the last 18 months, Worcester Bosch has had 150 boilers that have been running up to a 20% hydrogen blend. They are now trialling this in 670 homes in Gateshead.

Worcester Bosch has continued to increase the use of green gases, launching the Hy4Heat programme that is currently trialling 100% hydrogen boilers that are running in specially-built demonstration houses in Northumberland.

More importantly, Worcester Bosch has made significant progress with prototypes and testing, developing hydrogen ready boilers. These hydrogen boilers look almost identical to your typical everyday gas boiler and they are installed in pretty much the same way.

Similar to gas boilers, hydrogen boilers will be connected to the gas mains and then the hydrogen or natural gases will be fed to the boiler from there. 

There are a few small differences when it comes to the internal components of the new hydrogen boilers, such as a hydrogen-ready flame detector and burner.

It is not possible to buy a 100% hydrogen-ready boiler just yet and until there is a reliable supply of hydrogen gas, it wouldn’t make much sense to have one yet anyway. But when they are ready for consumers to buy, Worcester Bosch are already on top form.

Consumer review site Which? Has the following to say on Worcester Bosch:

“Reliability is the single most important consideration when buying a new boiler and Worcester Bosch has it in spades”

“We’ve been running boiler reliability surveys for 10 years now, and Worcester Bosch has impressed us every year”

Heating engineers often cite the stainless steel heat exchanger of the Viessmann as a clear advantage over the aluminium heat exchanger in the Worcester boiler. Stainless steel is a lot more durable than aluminium and resists corrosion over time.

If you get an issue with the heat exchanger in your boiler it’s a serious issue and often leads to the replacement of the boiler. Viessmann spies an opening and delivers a spinning backfist to Worcester Bosch, OUCH!

Worcester Bosch has a 4.6 rating on Trustpilot compared to Viessmann’s score of 4.5 out of 5 on Trustpilot, so from the customer point of view, Worcester Bosch boilers come out just ahead of Viessmann. Also, Worcester Bosch has a hefty 23k+ reviews, whereas Viessmann has less than 2k.

In terms of reliability, Worcester Bosch has the vote of the industry review sites and the public, whereas Viessmann takes the heating engineer vote.

Again, a close-run battle in which the Worcester brand just comes out ahead. KAPOW, Worcester Bosch performs a clean sweep and Viessmann hits the mat. Viessmann is looking dazed but there are no signs of giving up. On to the aftercare round we go…


The Worcester Bosch Greenstar 8000 Life offers a standard 5-year guarantee. Viessmann offers a standard 3-year warranty on the Vitodens 200-W.

Not only does the Worcester Bosch come with 2 extra years’ cover but it’s better cover. A guarantee offers you more protection than a warranty. If you aren’t sure what the difference is between a guarantee and a warranty, we’ve got you covered.

Worcester offers an extended warranty of ten years when the boiler is fitted with a Worcester System Filter by an accredited Worcester installer. WarmZilla offers a 10-year guarantee with any Worcester Bosch Life boiler installation.

Viessmann’s warranty offers the “Option to extend by a further 2 to 7 years, if fitted by a Viessmann Trained Installer and registered through the Viessmann Installer Portal (chargeable)”

To maintain the warranty on your boiler you will need to have an annual service carried out to ensure any claim you make against your warranty won’t be rejected.

Worcester enjoys an excellent reputation for their response time to customers calling on their guarantee with an issue, often getting an engineer out the next day. They are the most reactive boiler brand on the market in terms of customer care.

Viessmann is also very responsive when you need them, with many callouts attended within 24 hours, with no call-out charge.

Again, both companies offer excellent aftercare, but the added cover length and cover quality, along with the best reputation in the business for aftercare – we have to go with Worcester Bosch in the final round.

After knocking Viessmann to the mat, Worcester Bosch brings down a killer axe kick to end this brutal contest. The win goes to Worcester Bosch by TKO.


Despite Worcester beating Viessmann in the key factors of price, reliability, and aftercare; each round was very close. Both boiler brands are deservedly thought of as market leaders and innovators.

Both are very reasonably priced for the quality of boiler, both offer excellent aftercare and customer service and both have won numerous awards on their boiler ranges.

We would recommend Worcester as the number one choice boiler manufacturer as they are slightly cheaper, offer better customer service, and have a slightly better review score from the public on Trustpilot.

Industry awards can sometimes be biased depending on who has relationships with who, but consumers aren’t afraid to give their honest opinion and if they have a boiler that lets them down they will write about it.

There are occasionally issues getting Viessmann parts as they aren’t manufactured in the U.K, this is obviously not an issue with Worcester Bosch boiler parts.

Whichever of the two brands you go for you’ll be getting a reliable boiler from two companies with a proud history of innovation and customer focussed development.

If you’re looking to buy a new boiler then get a boiler quote from WarmZilla. It only takes two minutes, you don’t need to have any technical knowledge, and it’s all done online. Easy.

Remember, you can also use our Boiler Comparison tool to help you compare the boilers you are quoted, to help you decide on the best boiler for your home.

*Prices taken from https://www.plumit.co.uk/ at time of blog publication (installation not included).

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