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Last updated: 25th March, 2024


Worcester Bosch Vs Viessmann Boilers

Worcester Bosch Vs Viessmann Boilers

Which boiler will come out the winner between these two powerhouse boiler manufactures!

When choosing a new boiler, it can be hard to decide which brand to go for when they all seem to be offering the same promises in regards to reliability, durability and efficiency. Our top two bestselling boiler brands at iHeat are Worcester Bosch and Viessmann.

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An Introduction to Worcester Bosch

Founded in 1962, Worcester Bosch is probably the most well-known boiler brand. Their bestselling model, the Greenstar i, can be found in over one million UK homes and as the eleven time winner of Which? Best Buy it’s clear Worcester Bosch are a promising and popular brand and take a strong position amongst our best combi boilers.

An Introduction to Viessmann

Viessmann is a family-owned company that was founded in 1917 by Johann Viessmann and has since grown very popular in Germany and the rest of Europe, becoming leaders in the commercial heating space long before they entered the UK domestic market.

However, in more recent years, Viessmann boilers have started to appear in more and more UK homes as their advanced German engineering and innovation became more well-recognised.

When comparing these two boiler brands, we’ll be taking a look at four main points and comparing two of their most popular boilers, the Worcester Bosch Greenstar 8000 Style 30kW and the Viessmann Vitodens 050-W 29kW.

The four factors we'll be taking into account for this comparison are as follows:

  • Energy Efficiency

  • Technology

  • Price

  • Warranties

Worcester Bosch

Energy Efficiency

The Greenstar 8000 Style 30kW offers an amazing efficiency percentage of 94% and has a hot water flow rate of up to 10.7 litres of hot water per minute, making it one of the most efficient A-rated boilers.


The Greenstar 8000 Style boiler is packed with innovative new features which keep it performing at its best. Developed to suit virtually any domestic heating requirement, this is Worcester Bosch’s most powerful and connected wall hung boiler yet. With an easy to use, full colour display and connectivity, with the Bosch EasyControl app, you can control your home’s heating and hot water from anywhere, helping to keep costs down.

Unfortunately, their decision to keep the aluminium heat exchanger makes them drop below Viessmann, who use a stainless steel heat exchanger. The problem with aluminium exchangers is that they corrode easily and are less reliable, becoming clogged easily.


You can purchase a Worcester Greenstar 8000 Style for £2,395 including installation with iHeat. These boilers are at the higher end of the price range so you may be wondering why you should pay extra than other well known brands and if they are really worth it. The truth is, you’re paying for its guaranteed reliability, high efficiency and super sleek style.

Whilst it is possible to find cheaper boilers, they won’t be as reliable or long-lasting as a Greenstar Style 8000, costing you more in repairs and replacements in the long run. The average lifespan of a combi boiler is between 10-15 years, whereas a Worcester Bosch tends to last longer, between 16-20 years.


If our word on how great these boilers are isn’t enough, you can rest assured with 10 years guarantee on a brand new Worcester Greenstar 8000 Style when installed with iHeat.*


Energy Efficiency

This exceptional Vitodens 050-W definitely comes out on top as the most efficient boiler with an A rating and up to 97% efficiency. This boiler will seriously cut fuel costs whilst being incredibly reliable and offering the highest quality with its new stainless steel heat exchanger, making it extra robust whilst consuming relatively little natural gas. An exceptionally quiet operation means you won’t even notice as it works hard to provide you with heating, instantaneous hot water and an impressive hot water flow rate of 12.4 litres/min.


Viessmann uses Inox, the highest grade of stainless steel, which they manufacture exclusively in-house, making it incredibly reliable and less likely to get clogged or corrode. It also doesn’t require special fluids in the same way aluminium heat exchangers do and are compatible with clean water. This decreases the chances of damaging it, therefore increasing it’s chances of a longer lifespan.

This combi boiler will also integrate into any home with compact dimensions (707x400x350mm) and low weight (37kg), without compromising quality. With its easy to use LCD display and interface, you can control your heating to match your lifestyle and preferences.


Although the Viessmann Vitodens 050-W is cheaper than the Worcester Greenstar Style 8000 at £2,060 (including installation), you certainly won’t be compromising on quality. If this still seems expensive compared to other boilers, remember that Viessmann manufacture their stainless steel heat exchangers in house which is more expensive than sourcing cheaper aluminium from third parties. So whilst you are paying more, it is definitely worth it to ensure a longer boiler lifespan.


Still unsure about the reliability of a Viessmann? To ensure you get your money’s worth, you will receive a 10 year warranty on a Viessmann 050-W 29kW when installed with iHeat.*

Comparing the Best Viessmann and Worcester Bosch Boilers in 2024

When it comes to choosing a new boiler, homeowners often find themselves comparing the latest offerings from leading manufacturers. In 2024, Viessmann and Worcester Bosch remain at the forefront of the heating industry, each with their top-tier models designed to cater to diverse needs while emphasising efficiency, reliability, and innovation. Here's a closer look at how the best boilers from Viessmann compare to those from Worcester Bosch:

Viessmann's Top Models

Viessmann is celebrated for its cutting-edge technology and energy efficiency. The brand's use of stainless steel heat exchangers in models like the Viessmann Vitodens 200-W stands out for its durability and efficient heat transfer. This model, in particular, offers modulating output from 1.9 to 35 kW, making it highly adaptable to varying household heating demands. Additionally, Viessmann boilers often feature advanced control systems and connectivity options, allowing for easy integration with smart home systems.

Worcester Bosch's Leading Boilers

Worcester Bosch, a favourite in the UK market, is known for its reliable and user-friendly boilers. The Greenstar i series, for example, continues to be a popular choice for medium-sized homes, offering efficiency and simplicity in operation. Worcester Bosch's commitment to customer service and the availability of parts across the UK add to the appeal of their boilers. Models like the Greenstar 8000 Style combine modern design with performance, showcasing Worcester Bosch's attention to both aesthetics and functionality.

Efficiency and Sustainability

Both Viessmann and Worcester Bosch are committed to sustainability, offering models with high energy efficiency ratings that can significantly reduce carbon footprint and heating costs. Viessmann's innovative use of technology often leads to slightly higher efficiency ratings, while Worcester Bosch focuses on reliability and ease of use, ensuring that their boilers are both efficient and straightforward to operate.

Installation and Maintenance

The ease of installation and maintenance is another critical consideration. Viessmann boilers, with their advanced features, may require specialized installation knowledge, potentially leading to higher initial setup costs. Worcester Bosch's models are designed with the UK market in mind, ensuring that finding qualified installers and service technicians is generally more straightforward.

Price and Value

Price points between the two brands can vary, with Viessmann's models sometimes coming in at a higher initial cost due to their advanced technology and superior materials. However, the investment in a Viessmann boiler can pay off in the long run through energy savings. Worcester Bosch boilers offer great value, with competitive pricing and strong warranty offers that provide peace of mind to homeowners.

So which should you choose?

Despite Worcester Bosch being the most popular boiler brand in the UK, Viessmann takes the lead here, surpassing Worcester in almost all aspects. The Vitodens 050-W is more energy efficient than the Greenstar Style 8000, with its 97% efficiency and an impressive hot water flow rate of 12.4l/min, compared with Worcester’s 84% efficiency and 10.7l/min hot water flow.

Viessmann’s technology is also far more superior with their Inox heat exchangers that are a greater value for money than Worcester’s aluminium which are more likely to corrode, warp and break down. Despite these heat exchangers being more expensive to manufacture, the Vitodens is still more affordable than the Greenstar Style 8000, once again putting it on top.

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One advantage the Greenstar Style 8000 does have over the Vitodens 050-W is it’s appearance. Available in black or white with a sleek and expensive looking finish, this is an attractive boiler.

With iHeat, the warranties are the same, so no matter which you decide to purchase, you will be guaranteed a high quality boiler that lasts at least 10 years.* Get a free, fixed quote on a new Worcester Bosch or Viessmann boiler today.

*Boilers must be serviced annually by a Gas Safe Registered engineer.

iHeat New Boiler Costs

Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.

Effectively, new boiler cost can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer. 

Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.

Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type. Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat (guide only).

Installation Type

Price (inc VAT)

Combi to combi swap


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System to combi conversion


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New boiler install


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Back boiler to a combi


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System to system


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Frequently Asked Questions

What are the benefits of using a Viessmann boiler?

Viessmann boilers offer several benefits, including high efficiency, reliability, and durability. They are known for their innovative technology, such as stainless steel heat exchangers, which provide efficient heat transfer and a longer lifespan. Viessmann boilers also come in a variety of models to suit different needs and preferences, making them a popular choice for homeowners.

How can I maintain my Viessmann boiler?

To maintain your Viessmann boiler, it's essential to follow the manufacturer's guidelines and schedule regular servicing by a qualified technician. This includes tasks such as cleaning the heat exchanger, inspecting and replacing worn parts, checking for leaks, and ensuring proper ventilation. Additionally, it's crucial to monitor the boiler's performance and address any issues promptly to prevent further damage.

How good is a Viessmann boiler?

Viessmann boilers are considered among the best in the market due to their high efficiency, innovative technology, and durability. They offer a range of models that cater to different needs and preferences, including combi, system, and regular boilers. Viessmann's use of advanced features like stainless steel heat exchangers ensures effective heat transfer and longevity, making them a popular choice for those looking for a reliable and energy-efficient heating solution.

Why are Viessmann boilers so expensive?

Viessmann boilers are often seen as expensive due to their high-quality materials, advanced technology, and engineering excellence. The use of stainless steel heat exchangers, in particular, offers greater efficiency and a longer lifespan compared to the more common aluminium or cast iron options. This, combined with their energy-saving features and the potential for lower heating bills over time, contributes to their higher upfront cost but can offer better value in the long run.

Who makes Viessmann boilers?

Viessmann boilers are manufactured by the Viessmann Group, a German company established in 1917. The company is a leading international manufacturer of heating, industrial, and refrigeration systems, offering a wide range of products that prioritize energy efficiency, sustainability, and innovation.

Who are the top 5 boiler manufacturers?

The top 5 boiler manufacturers, known for their reliability, efficiency, and innovation, typically include:

  • Viessmann
  • Worcester Bosch
  • Vaillant
  • Baxi
  • Ideal

These brands are recognized for their comprehensive range of boilers suited to different household needs and preferences, offering various models that include combi, system, and conventional boilers.

What is the most reliable boiler brand?

Determining the most reliable boiler brand can vary based on individual experiences and specific model performance. However, Worcester Bosch consistently ranks highly in terms of reliability, customer satisfaction, and ease of repair, as evidenced by numerous surveys and industry reviews. Their reputation in the UK is particularly strong, supported by a wide network of service engineers and availability of parts.

What are the top 3 boiler brands?

The top 3 boiler brands, renowned for their quality, reliability, and customer satisfaction, are generally considered to be:

  1. Viessmann: Known for cutting-edge technology and high efficiency.
  2. Worcester Bosch: Praised for reliability, customer service, and ease of maintenance.
  3. Vaillant: Recognized for innovative heating solutions and a broad range of high-efficiency boilers.

These brands have established themselves as leaders in the heating industry, offering a variety of models to suit different needs while prioritizing energy efficiency, durability, and user-friendly design.

Stephen Day profile photo
Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.