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Worcester Bosch vs Viessmann boilers

Worcester Bosch vs Viessmann – Which is the Better Boiler?

Worcester bosch vs Viessmann comparison is now gaining traction in the UK, as more and more people are looking at the latest Best Buy Boiler report for 2019.

Worcester Bosch boilers are well-established and award-winning in the UK, and their boilers have been installed in over 1 million homes across the UK.  Their exposure is second to none compared to every other boiler company.

Meanwhile over in Germany and Europe, Viessmann‘s already massive market share continues to go up.  In the past decade, Viessmann have covered major technical ground and are now definitely one of the best boilers in the world.

If you would have asked me 12-13 years ago which boiler is best, I probably would have given you a different answer.  But times change, technologies evolve, and things change for the better. Today, when it comes to Worcester Bosch vs Viessmann, I’d say Viessmann edges it.

In May 2017 and 2018, one of UK’s largest independent consumer body surveyed more than 10,000 boiler owners online to ask them about their experiences with their boilers, which covered any breakdowns, problems, annoyances with their boiler.  From this they determined the reliability rating for each brand.  They also asked them to assess how satisfied they were, and how likely they would be to recommend their brand of boiler.

On top of gathering views of owners of each brand of boiler, they also collected opinions of heating engineers who work with boiler installations and repairs every day.

In April 2017 and 2018, they surveyed more than 200 heating engineers about their views on boiler build quality and their likelihood to recommend a boiler brand.  The availability of parts and spares.  How easy it is to fix a common fault with each brand of boiler.  And how easy it is to service them.

Worcester Bosch vs Viessmann both are unanimously regarded as 2 of 5 Best Buy Boilers from 300+ boilers tested.

Let’s take a deeper look at both boilers and simplify it further for you:

Worcester Boiler Review

worcester bosch vs viessmann, worcester bosch boiler

Our in-house heating experts and experienced engineers who have been installing boilers for decades now, say Worcester Bosch boilers’ build quality is among the best.  They offer a 5 year warranty as standard.  Should any time the thermostat fail, there is a manual override switch, which can save you on a cold winter night.  Worcester Bosch claim 1 out of every 10 boilers in the UK is theirs.  This claim may not be backed by actual figures.  In any case, we believe the landscape may be changing soon.  Don’t get us wrong, whatever is the verdict on Worcester Bosch vs Viessmann, Worcester are still one of the best boilers available in the UK.  They are market leaders for a reason.

Some features of Worcester Bosch boilers below:

  • Well known brand in the UK, a lot of satisfied customers.
  • Simple boiler controls with clear information display.
  • Low risk of condensate pipe freezing in severe weather.
  • Wide choice of controls enables greater comfort and economy.
  • Low energy pump reduces electrical usage.
  • Instantaneous hot water, always available.
  • Achieves an A+ ErP package efficiency rating for heating when installed with a Wave smart internet connected control.
  • High hot water flow rate.
  • Simple boiler control knobs with clear temperature display.
  • Frost protection is included, reducing frost risk if installed in a garage or a loft.
  • Larger two bathroom properties can be supplied by higher output options.
  • Inbuilt keyless filling link making it easy to refill your system.
  • Large CondenseSure style siphon built into the boiler – eliminates frost risk.

Viessmann Combi Boiler Review – Energy Efficient Heating

worcester bosch vs viessmann, Viessmann boiler

To read a detailed review of the Viessmann Vitodens 100-w, please click here

Fighting from the red corner in the Worcester Bosch vs Viessmann fight, Viessmann were (and are) world leaders in the commercial heating space long before they entered the UK domestic boiler market.  Viessmann commercial heating systems keep some of the largest buildings in the world, including stadiums, royal palaces and rival boiler manufacturer factories (*cough* Vaillant factory *cough*).

Viessmann have also continued to innovate, which shows in their extensive boiler range.  This has meant they’ve left the competition in the dust in some areas.  All Viessmann combi boilers are condensing boilers, which means they not only utilise the heat generated by combustion, but also create more heat by recycling the water vapour content.  This enables them to extract all of the heat contained in the flue gases and convert it into heating energy.  That would get wasted in an older non-condensing boiler.

All boiler manufacturers in the UK have condensing boilers now, so this isn’t something unique to Viessmann.  But we do believe Viessmann condensing boilers are definitely at the top of the pile.

Some features of Viessmann combi Boilers:

  • High quality Stainless Steel Inox-Radial Heat Exchanger
  • Long Term Reliability, Durability and High Energy Efficiency
  • High Efficiency – 94% and 98% and above on Vitodens 200-W
  • Works with Weather Compensation or Nest
  • In-Built Shock Arrester (Avoid Water Hammer Problems)
  • Combined PRV (Pressure Release Valve) and Condensate Pipe (Easy Installation)
  • Compact design and low weight
  • One of the quietest boilers in the UK
  • Available in outputs from 4.7 to 35 kW
  • Class A rated for Energy Efficiency
  • Backlit LCD Touch Screen for Easy operation
  • Extended 10 year warranty available if carried out by a Viessmann approved installer like Boilerhut

Viessmann Combi Boilers

There are many combi boilers available in the Viessmann range, so it’s worth doing the research to find out which boiler is best for you.  Below is a list of some of the Viessmann combi boilers currently on the market:

Want to know more about Viessmann combi boilers and how they work? Check out our best combi boilers 2019 post!

You may have already decided that Viessmann is the right manufacturer for you, in which case, good decision. However, if you require any further information or advice, our in-house heating experts will be happy to discuss this with you. All you need to do for a free, no-obligation quote is enter your postcode below, then hit the green button, it’s that easy!

Winner: Viessmann. But why?

Deal Changer = Viessmann Stainless Steel Heat Exchanger – Look ma, it rhymes!  

worcester bosch boilers vs viessmann, boiler heat exchanger

What really makes Viessmann combi boilers stand out in the Worcester Bosch vs Viessmann fight is the high performance, patented Stainless Steel Inox-Radial Heat Exchanger.  This is unique and exclusive to the Viessmann boiler range.  Many other boiler manufacturers including Worcester Bosch, Vaillant, Baxi and Vokera etc use an aluminium heat exchanger which in most cases sourced by a third party manufacturer.

So What’s the Big Deal with Viessmann and Worcester Bosch with Stainless Steel?

In the Worcester Bosch vs Viessmann fight, we believe this is a massive vote in Viessmann’s favor.  Stainless steel is highly resistant to corrosion in a wide range of pH levels.  Whereas for aluminum, 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.

And 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.

Stainless steel is also more expensive to source or manufacture compared to aluminum.  So, what makes more financial sense for a boiler manufacturer?  While aluminum is lightweight and initially has better thermal conductivity initially, but over the long run stainless steel will be much better value for money due to the longevity and better resistance to corrosion.  Aluminum 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.

Below is a comparison of the lifespan of a stainless steel heat exchanger (in blue) vs an aluminium heat exchanger (in red).

worcester bosch vs viessmann, boiler heat exchanger comparison

Built-In Shock Arrestor

As the Worcester Bosch vs Viessmann fight carries on, Viessmann lands another uppercut, as their boilers have a built in shock arrestor.  If you’ve never experienced a water hammer problem, first be grateful.  Second, make your central heating future proof and water hammer proof by buying a Viessmann boiler.  In simple terms, water hammer feels like a leprechaun hammering your water pipes every time you open the taps in your house.

In more technical terms, water hammer is a pressure surge or wave caused when 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. It is also called hydraulic shock.

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.

Don’t know what that is? Check out our article on ‘What is a condensate pipe?

Higher Efficiency for Longer

As shown in the heat exchanger comparison diagram above, longevity becomes a big factor in the Worcester Bosch vs Viessmann fight.  The use of condensing technology in Viessmann combi boilers means they can achieve efficiency of up to 98% (on select models) and are rated energy efficiency class A.  The heat exchanger cools the flue gases before they escape through the chimney.  In doing so, the water vapour contained in these gases is deliberately condensed.  This releases additional heat which is transferred into the heating system.

This also helps them modulate energy usage, so they hover between 5 KW and 30 KW as and when needed, saving you a tonne on energy bills.

This energy efficiency means you are saving a tonne on energy bills.  And by using less energy, you’re doing your bit for the planet by reducing your carbon footprint and leaving a better planet for our future generations.  Well done!  The stainless steel inside Viessmann boiler will last much longer without losing efficiency.

UK Best Buy Boiler Award

Viessmann have been awarded a “UK Best Buy Boiler” award by one of the most prominent independent consumer survey magazine once again for 2019.  To learn more about how Viessmann works closely with Which, click here.

worcester bosch vs viessmann, viessmann boiler range

Warranty is King

Last knockout punch in the Worcester Bosch vs Viessmann fight is landed by Viessmann again. While Worcester Bosch gives you 5 years standard warranty, Viessmann ups that to 7-10 years’ warranty, and a slew of discounts if you get it installed by an Viessmann-approved installer or a premium partner like Boilerhut.  That’s almost double the warranty time, on top of Viessmann being superior in terms of technology and energy efficiency.

High Quality Boiler Installations from Boilerhut

From your first online boiler quote or a phone call/email to final installation, Boilerhut can install either Worcester Bosch vs Viessmann, Vaillant or Ideal boilers within a few days.

All our engineers are Gas Safe, OFTEC and APHC registered/accredited.  And because we are a Viessmann-approved installer, our engineers are trained to the highest standard and have undergone a rigorous training course.  Also in addition to the training, we have a very close working relationship with Viessmann which means we have access to longer warranties, discounted parts and direct access for service and warranty issues.

We can get most issues sorted within 24-48 hours.

Don’t take our word for it, read our customer reviews on Trustpilot.  We are rated excellent with 5-stars.

worcester bosch vs viessmann, trustpilot reviews, installer reviews

A lot of other companies take up to two weeks AFTER the survey visit for a boiler installation. Boilerhut are working on exciting new technology which will reduce that time to just a few days. You can now get an online estimate/quote within minutes.

To Book Your Free Home Survey – Call: 029 2009 9898

Or enter your postcode below and get a free online quote:

12 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


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