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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

Quick jump…

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.

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The Worcester Bosch boiler range

worcester bosch boiler range

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

The Viessmann Boiler Range

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.


  • 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
    viessmann boilers stainless steel 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.
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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.

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16 replies
    • Ashish Sebastian
      Ashish Sebastian says:

      Hi Andrew,

      We agree. As a business it makes sense to install Viessmann boilers in 2018, because there are next to no complaints! Viessmann have definitely listened to feedback from years ago and made positive changes.

      We’d say Viessmann’s range is definitely the best in Europe right now.


  1. Jay Kay
    Jay Kay says:

    Great Article and very helpful. Thankyou! Trying to choose between these two myself. I’m currently leaning towards the Veismann Combi..
    My question is, why don’t Worcester Bosch use Stainless Steel Heat Exchangers?? There must be a reason they’re sticking to Aluminium when most of the evidence shows the Stainless Steel ones are a LOT better.. Doesn’t make sense to me!
    Hope you can help..
    Look forward to your reply.

    • Ashish Sebastian
      Ashish Sebastian says:

      Hi Jay,

      Thank you for your comment. A very good question, in fact we’ve been wondering that ourselves! Only Worcester Bosch can provide the real technical answer to that question. However, some of the heating experts and industry insiders think the following may be the case:

    • 1. Worcester Bosch are the market leading boiler brand in the UK, and so don’t have to push to innovate. Aluminium is cheaper compared to stainless steel, which helps WB to keep the costs down. And as long as the boilers work fine for at least 10 years, their customers don’t seem to mind either.
    • 2. Viessmann’s market share is not as high as Worcester Bosch, and so that makes them hungrier. They were world leaders in commercial boilers way before they entered the domestic boiler market. So, their sizable expertise and manufacturing prowess allows them to manufacture their patented inox-radial heat exchangers, MatriX cylinder burners, thermal stores (all stainless steel) in-house and still compete at the same price point against WB and other rivals.
    • So, in effect Viessmann are offering a better quality product to gain market share. The only advantage aluminium has over stainless steel is cost and weight. The slight weight advantage is inconsequential for boilers.

      Corrosion is the major factor here. Aluminium corrodes so much faster compared to stainless steel, and corrosion leads to loss in efficiency over the years. Below is a graph explaining this:

      Stainless Steel vs Aluminium Heat Exchanger

      Why do Worcester Bosch still use aluminium? We don’t know. Best ask them yourself, but we doubt they’ll reply. 😊

      Best regards,

      • Jay Kay
        Jay Kay says:

        lol..!! Great stuff. Thanks for your honest reply.
        I’ll be in touch about a Viesmann Bolier for Semi. (Extended)
        I bathroom with Bath and (non-electric) Shower. Total of 12 Radiators. Which model would you recommend? I’ve heard the 200 series is better than the 100..?
        Thanks again.

        • Ashish Sebastian
          Ashish Sebastian says:

          Hi Jay,

          Please call our office on 029 2009 9898 and have a discussion with one of our heating experts for the 200-W.

          For the 050-W and 100-W you can always get an online boiler quote on this page:

          Our intelligent quoting system will give you a fairly accurate price estimate, which can be discussed with our heating expert and firmed up later on.

          Either one of Viessmann’s range, the 050-W, 100-W and 200-W will serve you well. But yes, the 200-W is their premium offering. It’s their most powerful non-storage combi boiler, walks a thin line between a commercial and residential boiler. It’s also one of the most energy efficient boilers available in the UK at 98% efficiency.

          This page gives a side-by-side comparison of the three models:

          Best regards,
          Boilerhut Ltd

  2. Jilli Dee
    Jilli Dee says:

    I’m currently doing the same thing, trying to choose between a Worcester Bosch and a Viessmann. Moved in to this property in 2017, previous owners installed a Raven Heat white star which is at least 10yrs old but recently its making loud noises and struggles to provide hot water. The boiler is unfortunately installed in a bedroom so need a quiet boiler. Read many recent reviews about the Viessmann and there are a lot of negative reviews. The gas engineer recommends the Viessmann as he fits both. But I’m still undecided. Really need advice or opinions.

    SIMON TAYLOR says:

    I have a 4 bedroom house with 3 bathrooms and 15 radiators- I want a wall hung heat only boiler do Viessmann do one that is big enough.

    Must I have the Viessman fitted by Boilerhut or can it be sourced elsewhere as I have a Gas Safe plumber who I know and trust implicitly in my property. If he fits it so are there any catches on the warranty.


    • Bryn Lloyd
      Bryn Lloyd says:

      Hi Simon,

      Thanks very much for your enquiry. Fortunately, we do offer a boiler-only purchase option which you can then have installed by a Gas Safe Registered Engineer. Bear in mind that if it’s fitted by a third party, your warranty will be limited to 5 years. However, if it’s installed by Boilerhut directly, we can extend that warranty to 10 years to ensure maximum reliability and peace of mind. For more information and advice you can speak to Paul at 07796 898985.

      You can also get a free, no obligation online boiler quote here:

      Best Regards,
      Bryn Lloyd
      Boilerhut Ltd

      • Bob
        Bob says:

        Simon, your answer is factually incorrect and misleading! Very disappointing for a supposedly reputable company. So I’ll provide the correct answer.
        Any Gas Safe Registered engineer who is Viessmann factory trained can provide the 10 year warranty for a one off cost of £120.00 paid directly to Viessmann. My advisc to people considering Viessmann is to seek a local installer via the Viessmann website and then get them to provide customer references. Shop around for the best boiler price if you wish.

        • Bryn Lloyd
          Bryn Lloyd says:

          Hi Bob,

          Any Viessmann-approved installer who has attended the Viessmann training course can supply you with extra warranties. However, if we use the 050-W and 100-W as examples, there are differences in what’s available depending on who carries out the installation.

          Viessmann Vitodens 050-W:

          Non-Viessmann Approved Installer – 3 years
          Viessmann Approved Installer – 7 years

          Viessmann Vitodens 100-W:

          Non-Viessmann Approved Installer – 7 years
          Viessmann Approved Installer – 10 years

          We hope you find this information useful. If you require any advice and support, please contact us via or call our head office on 029 2009 9898.

          Kind Regards,
          The Boilerhut Team

  4. Robert Masterman
    Robert Masterman says:

    I have A 12-year old viessmann vitodens 333F which has been a constant problem from day 1. The solenoid valve failed 3 months out of warranty (Viessmann didn’t want to know!) since then it has needed more visits to reset it than I can remember, and now I’m told it needs a new fan unit ((£540) and expansion vessel (£120) So much for German engineering and reliability.
    I will be having it replaced with a Worcester-Bosch as soon as I can.

    • frizzbee30
      frizzbee30 says:

      We have a Worcester, fitted by British Hash some time ago, in fact even though we wanted a condensing unit (they were being pushed at the time by the gov), the BG surveyor told us that ‘there was no such thing as a condensing combi’, and ‘no technically possible, only works on storage boilers’ (they got a job lot from worcester at a discount, when the shift happened to condensing, and basically ‘lied’ them into homes as old tech), so we got the piece of utter garbage we have, which currently has a bathroom radiator acting as an expansion vessel (fixed pushed to March!!), and dripping water from the top of boiler.

      Anyway from install (or rather chop job done by BG), within 6 months breakdown (expansion vessel..never fail..2 day job), we then had a resident BG engineer for about 2 years.

      It has become so regular that we have 2 callouts per year for faults, this is actually fault 4 or 5, within about 9 months.

      ‘It’s an old boiler’, well, when every component, except the bloody tin case, including the pigging expansion vessel has been swapped out, then no…it’s a brand new boiler, nearly everything has been swapped in the last 3 to 4 years, yes every bloody component, gas valves, hear exchange, pump, burner, mainboard, 2 bloody pressure valves in 6 months etc, etc it bloody well isn’t.

      So yea, so sick to the hind teeth of worcester, I think we are going to get shut before BG get around to sorting the latest ‘workaround patch’ in late March…

  5. Catherine Cowie
    Catherine Cowie says:

    I’m currently trying to choose between a Worcester and a Viessman. We have an old system (with a back boiler) currently and have been told that the Viessman Vitodens 050-w 29kw is very good, but it’s not a good idea to fit one onto an old system because some part of it is very narrow (narrower than Bosch) and if there is any sludge in the system (even after a flush) it can block it up. Can anyone verify this?
    From what I can see online, the Viessman has more potential problems despite its stainless steel heat exchanger and various innovations, and i wonder if this is because the customer care is poor?
    I have been quoted a 10 year warranty on this boiler (by an approved installer) which again is confusing because it doesn’t tie up with what has been stated by Bryan Lloyd earlier in this chat.
    Oh for wisdom to find a way through this maze!!!

    • Bernard Morgan
      Bernard Morgan says:

      Hi Catherine. Yes, it is a maze! If the system is flushed correctly and a high quality filter was used, your Viessmann is serviced yearly, and if you keep the condition of the water good, you will have no issues. This applies to all manufacturers.


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