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Last Updated on November 27, 2023

Viessmann vs Worcester Bosch Boilers

Viessmann vs Worcester Bosch boilers is a debate that’s been developing over the last few years between the two premium choices available for domestic boilers in the UK.

Both are high quality and built for high efficiency.

In this guide, we look closely at the two boiler manufacturers and compare them based on the following criteria:

Product range
Quality of components
Customer service
Accolades
Market share

More information:

< Go to main Viessmann page

< Go to main Worcester Bosch page

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About Worcester Bosch

Worcester Bosch was founded in 1962 by Cecil Duckworth as Worcester Engineering Co Ltd in Worcester, England.

However, as the name suggests, the company has been a subsidiary of Robert Bosch GmbH since 1992.

With its headquarters in Warndon, Worcestershire, Worcester Bosch manufactures its gas boiler range at this site and its oil boilers at a further site in Clay Cross, Derbyshire.

Worcester Bosch’s product range includes gas and oil boilers, hot water cylinders, heat pumps and solar water heating systems.

Worcester Bosch has been awarded Which? Best Buy status for 11 years for its Greenstar gas boiler range and was awarded Which? Best Buy status for its oil boilers in the 2020 Which? Report.

Worcester Bosch has also been awarded the Royal Warrant by the late Queen for supplying hot water products to the Royal Family.

A household name, Worcester Bosch is the current market leader for domestic boilers in the UK. Its boilers have been built to the highest quality, installed in over one million homes across the UK.

About Viessmann

Founded in 1917, Viessmann is headquartered in Allendorf, Germany and has been a family-owned company since its inception.

Today, the company manufactures heating, industrial and refrigeration systems and operates in 74 countries across the world.

Viessmann has operated in the UK since 1989 and from its UK headquarters in Telford, the company offers a product range including gas boilers, oil boilers, air and ground source heat pumps, steam boilers, biomass boilers and combined heat and power generation.

Each year, Viessmann trains approximately 2,500 installers, contractors, specifiers and architects on its products across the UK. Whilst parts for Viessmann boilers are readily available from Plumbase stores throughout the country.

Whilst not as well-known in the UK as Worcester Bosch, Viessmann is increasingly gaining traction across the UK – this is in part due to its entire Vitodens range being awarded Which? Best Buy status every year since 2017.

Over the past decade, Viessmann has invested heavily in its technology and offers products providing market-leading efficiency levels.

The Worcester Bosch boiler range

Please click here for more information on the entire Worcester Bosch boiler range that we offer.

The Viessmann Boiler Range

Please click here for more information on the entire Viessmann boiler range.

Our thoughts on Viessmann vs Worcester Bosch

Our team comprises of heating engineers who have been installing boilers for decades. Here are their current thoughts on the Viessmann vs Worcester Bosch debate:

Worcester Bosch

Amongst the best build quality of any boiler range currently available in the UK
Backed up by the engineering strength of the Bosch brand, Worcester Bosch has long been known for its build quality and this continues across the 2023 range.

Great guarantee – 5 years as standard
Worcester Bosch’s guarantee is comprehensive and covers replacement parts, call out and labour costs. However, this is only 5 years as standard. To qualify for anything longer than this, you will need to buy the additional guarantee and the boiler must be installed by a Worcester Bosch trained installer.

Boilers in the range feature manual override switches
Should the thermostat fail, this will prove to be a saviour on cold winter nights.

Simple boiler controls across the range with clear information displays
There is nothing complicated about the controls on any of the boilers in the Worcester Bosch range, and everything is clearly presented and easy to find.

Low risk of the condensate pipe freezing in severe weather conditions
Though a simple fix, a frozen condensate pipe can be frustrating and lead to temporary heating and hot water outage. Thankfully though, the Worcester Bosch range features condensate pipes that are resistant to freezing.

Compatible with a wide range of controls
Allowing for increased energy efficiency and smarter operation, the Worcester Bosch range is compatible with a wide range of thermostats and smart heating controls.

Integrated low energy pumps
An integrated low energy pump in boilers across the range will enable you to reduce your electricity usage.

Included frost protection
This will reduce frost risk if installed in a garage or a loft.

Viessmann

Innovation
Viessmann invests heavily in innovation and this is shown across its boiler range with each of the boilers featuring cutting-edge, future-proof technology.

Quiet operation
With an operating volume of just 36dB, the Viessmann Vitodens 200-W is one of the quietest boilers available to purchase in the UK.

To put this into perspective, 36dB is barely more than a whisper and quieter than an A-rated refrigerator.

This isn’t just exclusive to the 200-W though, all of the boilers across the Viessmann range have been engineered for quiet operation.

Efficiency
Efficiency is key to the Viessmann boiler range and is the result of Viessmann’s investment in innovation and higher quality internal components. This has paid off with the Vitodens 200-W and the Vitodens 222-F both having efficiency ratings of 98% and no boiler in the Viessmann range dipping below 93%.

Weather compensation
All of the boilers in Viessmann’s Vitodens range are equipped with weather compensation technology. Utilising an outdoor sensor, this works with the boiler to regulate the temperature based on the temperature dropping or rising outside. This will assist in achieving energy bill savings.

Stainless steel Inox-Radial heat exchanger

As you can see in the graph above, Viessmann boilers retain efficiency for longer.

Why is that?
Whilst Worcester Bosch utilise aluminium for its heat exchangers, Viessmann utilises stainless steel with 10.5% chromium content and 1.2% carbon by mass. This means that Viessmann boilers have increased corrosion resistance at a wide range of pH levels and aren’t susceptible to the levels of corrosion that aluminium is.

This is a huge factor in the Viessmann vs Worcester Bosch debate, according to many experts.

Extended 12-year warranty available
Viessmann offers a standard 5-year parts and labour warranty, however, this is extendable to 12 years for the 100w range and 10 years for other ranges, if installed by a Viessmann trained and authorised installer, like Boilerhut.

Winner: Viessmann

Both Worcester Bosch and Viessmann offer quality engineering across their boiler ranges. However, when pitched against each other, Viessmann stands out as the better boiler for us.

Quality of components

For us, Viessmann winning is largely due to the quality of their components. Unlike Worcester Bosch, Viessmann does not use plastic components in any of its boilers. Nor do they utilise an aluminium heat exchanger like Worcester Bosch. It is the quality of their internal components which really sets Viessmann apart.

Stainless steel heat exchanger

A patented product, the Stainless Steel Inox-Radial Heat Exchanger is highly resistant to corrosion in a wide range of pH levels. Whereas for aluminium, if the proper fluids are not used to produce and maintain a narrow pH range, it will corrode much faster. Without the use of proper fluids, you may damage an aluminium heat exchanger. If you do damage the heat exchanger, your warranty will be voided, because the manufacturer will cite improper use of fluids.

In direct comparison, stainless steel heat exchangers do not require special fluids, are compatible with plain clean water and commonly available propylene glycol.

Whilst aluminium is lightweight and has better thermal conductivity initially, stainless steel will be of much better value for money due to its longevity and better resistance to corrosion. Aluminium will rust, corrode, warp, and break down long before stainless steel, so investing in a boiler with a quality stainless steel heat exchanger will increase the useful life of your boiler.

Granted, stainless steel is more expensive to source and manufacture but it is a long-term investment. An investment Viessmann made by manufacturing it in-house at their facility in Germany for quality control.

Built-In Shock Arrestor

The built-in shock arrestor used in Viessmann’s boilers is another plus point for the range and will reduce any water hammer issues experienced.

If you are unaware of what water hammer issues are, they are the loud rattling of pipes every time a tap is opened. A water hammer is a pressure surge or wave caused when a fluid (usually a liquid but sometimes also a gas) in motion is forced to stop or change direction suddenly (momentum change). A water hammer commonly occurs when a valve closes suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe.

PRV and Condensate Combined

Throughout the Viessmann boiler range, the pressure relief pipe and condensate are combined. This gives the installers more choice in siting the boiler, allowing a lot more flexibility with replacement, retrofitting, and new boiler installations.