Vaillant Vs. Viessmann Boiler Re February 22, 2023

Vaillant Vs. Viessmann Boiler

Engineer fitting a boiler

When it comes to boiler brand and quality, both Vaillant and Viessmann boilers are a great place to start when looking for an efficient and robust boiler. 

With that said, purchasing a new or replacement boiler is one of the most important buying decisions a homeowner can make.  And so, you want to be extra careful in choosing which is the best boiler for your home, because you don’t change boilers every year, whichever boiler you choose will have to last you between 10-15 years.

If you are looking for more cost-friendly boilers, there are plenty of other boiler brands such as Vokera and Ideal boilers.

WarmZilla also offers boiler finance for those looking to spread the costs for a more premium boiler. 

This article will be comparing Vaillant and Viessmann boilers against each other, including comparing price, efficiency, warranty, and features. 

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 winner.

In this article, we’ll be comparing;

In amongst this, we will be comparing reliability, customer reviews, warranty, aftercare, and prices.

Vaillant Brand History

Vaillant boiler

Vaillant was formed way back in 1874 by Johann Vaillant in Remscheid, Germany. Johann Vaillant founded his own workshop as a copper beater and pump maker.

Many inventions have been credited to Vaillant over the years including modern-day central heating in 1924. Previously each room was heated individually by stoves or fireplaces until Vaillant introduced the central heating boiler that could heat multiple radiators simultaneously – revolutionising home heating.

The Vaillant boiler range has been given a Which? Best Buy award and they have also been awarded a Quiet Mark Accreditation, from the Noise Abatement Society for their quiet running boilers.

For a full timeline of the Vaillant, company history click here.

Viessmann Brand 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 Bosch’s, starting in 1928, where Johann Viessmann was asked by a local gardener to build a boiler for his greenhouse. 

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. 

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.

Now for the good stuff. Let’s compare the Vaillant EcoTec Pro 30kW and the Viessmann Vitodens 050-W 29kW combi boilers. 

Vaillant EcoTec Pro 30kW Combi vs. Viessmann Vitodens 050-W 29kW Combi

Comparison Table 

Boiler MakeVaillantViessmann
Boiler ModelEcoTec ProVitodens 050-W
Boiler TypeCombiCombi
Fuel TypeGasGas
CH kW Output 25kW24kW
DHW kW Output30kW29kW
Efficiency Rating93%93%
Band RatingA-RatedA-Rated
Standard Warranty2 years3 years
Flow Rate12.3 l/min12 l/min
ErP RatingA Heat | A WaterA Heat | A Water
Dimensions (HxWxD)720mm x 440mm x 338mm707mm x 400mm x 350mm

When comparing these combi boilers, straight off the bat, we can see that they are quite similar in how they perform. They both offer an efficiency rating of 93% and an ErP A-Rating, meaning that both boilers perform to a high standard and both also contribute to lowering your energy bills. 

With outputs of 29kW and 30kW, both boilers are suitable for medium-sized homes with up to 15 radiators and 2 bathrooms. 

Both boilers are similar in their standard manufacturer’s warranty. The Vaillant EcoTec Pro has a standard 2 years warranty that can be extended to 7 years for free if you register your boiler through Vaillant Advance. But WarmZilla beat this by a mile, offering a massive 10-year warranty when your purchase through us. 

In addition to this, the Viessmann Vitodens 050-W combi boiler range has a standard 3 years manufacturer’s warranty that can also be extended to 7 years if registered with a Viessmann Trained Installer, however, when purchasing with WarmZilla, you will receive a 10-year manufacturers warranty. So, when it comes to the battles of warranty, it’s not really about who offers the better warranty, it’s more about when you’re going to buy your new boiler with us at WarmZilla 😉

Everyone loves an all-singing, all-dancing boiler with all the latest technology included, so let’s compare what the Vaillant EcoTec Pro and the Viessmann Vitodens 050-W combi boilers have to offer.

The Vaillant EcoTec Pro Combi boiler range includes:

  • Quiet Mark accreditation 
  • Which? Best Buy accredited 
  • Removable side pales for improved accessibility and ease of installation
  • Compatibility with controls 
  • Built-in frost protection 
  • Compact and lightweight 

The Viessmann Vitodens 050-W Combi boiler range includes: 

  • Ultra-compact in size
  • High-quality stainless steel Inox-Radial heat exchanger 
  • Low CO2 emissions to help the environment 
  • Digital LCD display
  • Optional room thermostats
  • Plus in time clock and wireless receiver 
  • Endorsed by Trustpilot 
  • Boiler Plus Compatible
  • Smart Home controls

When looking at both boiler’s features, Viessmann steals the show, offering a lot more to entice their customers, now you would think that will all these additional touches, the Viessmann would be more costly. Well, it’s not. 

Vaillant EcoTec Pro 30kW – £2,069 inc VAT*

Viessmann Vitodens 050-W 29kW – £1,969 inc VAT*

Considering both boilers are very similar when it comes to what they offer, the Viessmann combi boiler is £100 cheaper.

When purchasing either of these boilers with WarmZilla, boiler installation is included, along with the flue kit needed, a free Honeywell RF wireless thermostat, a system cleanse, a magnetic filter for ongoing protection, chemical inhibitors for added protection, and free removal of your existing boiler and parts.

It is also important to note that all boiler installations will be done by a qualified Gas Safe Engineer. 

In summary, when comparing the Vaillant EcoTec Pro 30kW and the Viessmann Vitodens 050-W, although both boilers offer great reliability, efficiency, and warranty, the 050-W takes first place for us by offering more features at a lower price!

Vaillant EcoFit Pure 25kW System vs. Viessmann Vitodens 200-W 25kW System

We’ve compared a combi boiler model from both brands which have proven to be pretty similar. Let’s take a look at comparing a system boiler from both brands. 

Comparison Table 

Boiler MakeVaillantViessmann
Boiler ModelEcoFit PureVitodens 200-W
Boiler TypeSystemSystem
Fuel TypeGasGas
kW Output25kW25kW
Efficiency Rating94%98%
Band RatingA-RatedA-Rated
Standard Warranty23
Flow RateN/AN/A
ErP RatingA HeatA Heat 
Dimensions (HxWxD)700mm x 390mm x 295mm 700mm x 450mm x 360mm 

Straight off the bat, we can see a difference in efficiency ratings. With an efficiency rating of 98%, the Viessmann Vitodens 200-W system boiler is one of the most efficient boilers on the market. However, Vaillant’s EcoFit Pure is not far behind with a solid 94%.

When it comes to efficiency ratings, the higher the rating, the more energy-efficient your home is and the lower your fuel bills will be. Both of these system boilers have great ratings, to help keep your bills at an affordable price. 

Both the Vaillant EcoFit Pure and Viessmann Vitodens 200-W have an output of 25kW, perfect for homes with moderate demand for central heating and instant hot water. 

System boilers are ideal for families that require hot water ‘on tap’ (excuse the pun 😉). This is because system boilers can store heated water in a separate hot water cylinder to be used when needed. However, it is important to remember that with system boilers, you will need the space in your home for an additional tank. 

When looking at the comparison table, both boiler models have similar warranty lengths. The standard Vaillant EcoFit Pure system boiler warranty is 2 years, however, this can be extended to between 7 and 10 years when your boiler is fitted with a Vaillant Advance Installer. The Viessmann Vitodens 200-W system boiler starts with a 3 years standard warranty, but this can also be extended to 10 years when registered through the Viessmann Installer Portal. 

This is probably a great time to mention that if you don’t register your warranty within 30 days of installation as well as ensure that you have annual servicing on your boiler, your warranty becomes void. 

Did you know that WarmZilla has a free Boiler Comparison Tool? This tool allows you to compare 3 boiler brands or models at one time, to help you find the perfect boiler for your home. So if you really want to put these two boilers to the test, or even compare them with another boiler, go and take a look!

Let’s take a look at the features. 

Vaillant EcoFit Pure System boiler range includes: 

  • Compact size so that it can fit in a kitchen cupboard 
  • Quiet Mark Approved
  • Compatibility with vSmart controls 
  • Patented 4-sided cooling and water agitation of the heat exchanger for longer life 

Viessmann Vitodens 200-W System boiler range includes: 

  • Modulation range up to 1:17
  • Durable and efficient thanks to Inox-Radial heat exchanger
  • MatriX-Plus burner with long service life due to the stainless steel MatriX surface
  • Lambda Pro Plus combustion controller for all types of gas
  • Quiet operation due to low fan speed
  • 7-inch colour touch display for ease of operation, also possible via ViCare app
  • Integrated WiFi interface for internet connection
  • Energy cockpit for visualisation of energy generation and energy consumption
  • Suitable for integration of a solar thermal system

Alike the Viessmann 050-W combi boiler, the Vitodens 200-W system boiler has a lot more to offer when it comes to features, but let’s look at the price difference. 

Vaillant EcoFit Pure 825 System – Between £840- £1,160 (boiler only)**

Viessmann Vitodens 200-W 25kW System – Between £1,191 – £1,444 (boiler only)**

Again, these prices do not include installation or labour costs, however, unlike the unexpected lower cost of the Viessmann Vitodens 050-W combi, the Vaillant is the winner for this round. 

If you’ve reached this point in the blog and you’ve decided that a Vaillant boiler is the one for you, but you’re not sure which model to choose from. Stress no more, as we have a blog that covers the best Vaillant boiler for your home to help you make your final decision.  

You could argue that the increase in price for the Vitodens 200-W system boiler is a result of it being a newer, upgraded model that has recently been released. 

All in all, for two very similar boilers, when it comes to performance, with the Vaillant being a massive £284 cheaper, the Vaillant takes the gold in this round. 

It’s 1-1 at this point! But who’s going to be the overall champion?


Vaillant EcoTec Plus 18kW Regular vs. Viessmann Vitodens 100-W 19kW Regular

Comparison Table

Boiler MakeVaillantViessmann
Boiler ModelEcoTec PlusVitodens 100-W
Boiler TypeRegularRegular
Fuel TypeGasGas
kW Output18kW19kW
Efficiency Rating94%94%
Band RatingA-RatedA-Rated
Standard Warranty55
Flow RateN/AN/A
ErP RatingA HeatA Heat
Dimensions (HxWxD)600mm x 375mm x 316mm600mm x 375mm x 285mm

Regular boilers are ideal for homes with a high demand for instant hot water. This is because they are designed to work alongside an additional hot water cylinder and cold water tank, which are kept in an airing cupboard and (usually) the attic of your home. Cold water is heated and then stored inside the cylinder at optimum temperature, ready for when you need it. 

However, regular boilers are not recommended for smaller homes with limited space because they require additional hot and cold water tanks. 

The Vaillant EcoTec Plus regular 418 and the Viessmann Vitodens 100-W 19kW are both similar in hot water outputs, both ideal for homes with up to 13 radiators and a single bathroom. 

Both regular boilers are similar in terms of efficiency. With a rating of 94% and an ErP A-rating, both boilers are extremely efficient and will help to reduce your energy bills. 

When it comes to warranty, both boilers have identical standard manufacturer warranty lengths. The Vaillant EcoTec Plus regular boiler has a warranty of 5 years which can be extended to 7 years when installed by a Vaillant Installer. However, WarmZilla offers an 8-year warranty on the EcoTec Plus boilers.

When you order a Viessmann 100-W regular boiler with WarmZilla, you will receive a massive 10-year manufacturer warranty!  Yes, 10 years! So you won’t have to worry about your boiler for a long time. Let’s look at their features. 

Vaillant EcoTec Plus Regular boiler range includes: 

  • Rear flue options for easy installation 
  • Compact dimensions 
  • Large backlit plain text display 
  • Push-button programming
  • Compatibility with Vaillant controls 
  • Removable side panels for easy access

Viessmann Vitodens 100-W Regular boiler range includes:

  • LPG conversion available 
  • Compact dimensions
  • Weather compensation option
  • Compatible with smart thermostat 
  • No pump overrun requires
  • MatriX cylinder burner 
  • Inox-Radial heat exchanger
  • Built-in frost protection 
  • Quiet operation

Time for prices…

Vaillant EcoTec Plus 418 Regular – £720 – £1520 (boiler only)**

Viessmann Vitodens 100-W Regular 19kW – Between £794 – £1,358 (boiler only)**

Once comparing both regular boilers, both are similar in performance, however, on this occasion, thanks to its incredible warranty of 10 years with WarmZilla and its endless list of features and price difference, Viessmann has pulled it out of the bag!

Vaillant Vs. Viessmann Brand Reviews and Reliability

Before we decide who is the stronger candidate for first place in this particular best boiler tournament, let’s see what customers say about these brands themselves. 

We’ve looked at both Vaillant and Viessmann’s Which? Best Buy ratings as well as some Trustpilot reviews. 

During the latest Which? Best Boiler Brand Survey, Vaillant bossed it, scoring a massive 80% overall brand score, passing well-known boiler brands such as Worcester Bosch. Viessmann running not far behind, in third place, with an amazing 72%. 

These scores show us that both brands are valued highly by their customers and that each brand’s customers are more than happy with their boiler. 

Let’s delve a little deeper into individual brand scores and customer opinions. 

When looking at Vaillant’s survey scores, here is what they were awarded:

Vaillant Which? Best Boiler Brand Survey results: 

Reliability 4 stars
Brand Score 5 stars 
Engineer Recommendation 4 stars

Which? Have said  “Vaillant consistently scores well in our annual boiler survey and this year is no exception. Vaillant have a five-star customer score, a good reliability record, and the glowing praise of respected Which? Trusted Traders heating engineers. Vaillant is the best gas boiler brand of any included in our survey this year, which makes it a Best Buy. We think Vaillant is great and definitely a good choice of boiler for your home.”

Vaillant has over 15,000 reviews on Trustpilot, with an overall score of 4.6 stars out of 5. 90% of Vaillant’s reviews are above average. This shows us that Vaillant has built a well-known, reliable, and efficient brand that offers great boilers at a great price. 

Here’s what a handful of Vaillant’s happy customers have had to say about their Vaillant boilers: 

“I had a brand new Vaillant EcoTec Pro installed recently and I love it, could not ask for better with both the boiler and WarmZilla who I purchased it from. Great service and a great boiler, I’m so glad I have hot water again, I’m just waiting on receiving my guarantee paperwork, I’m really really happy with everything”

“I’m really pleased with my new Vaillant, it’s very quiet and easy to use. Would highly recommend.”

“Our new Vaillant boiler is excellent and is so much quieter than the old one, it’s a thumbs up from us.”

Now let’s compare this to Viessmann’s survey scores:

Viessmann Which? Best Boiler Brand Survey results: 

Reliability 4 stars 
Brand Score 5 stars 
Engineer Recommendation 4 stars 

“Viessmann boilers have been Best Buys for the past few years, but they just miss out this year. Viessmann still makes great boilers that are reliable and loved by people who own them. Heating engineers rate them too, just not quite as high as the very very best, so they narrowly miss out on a Best Buy.”- Which? 


Although Viessmann only has 2.2k reviews on Trustpilot, they too have scored 4.6 stars out of 5, and 89% of their reviews are above average. 

Here are some of Viessmann’s customer reviews: 

“Boiler is now a year old and I have to say it’s been absolutely brilliant. Great boiler and would definitely recommend”.

“Boiler is quiet and efficient. Build quality looks to be excellent. It has now been in for 9 months and we are very pleased with it”.

“Absolutely delighted with my Vitodens 100-W, as I knew I would be! I proofread heating manuals for a living and had my heart set on a Viessmann boiler. Our local installer was GREAT! Nothing was too much trouble and he worked hard to make sure retrofitting this lovely new boiler into our old system was fault-free. EXCELLENT!”.

Vaillant Vs. Viessmann Aftercare

Viessmann boiler

Here at WarmZilla, it is extremely important to us that five-star service is provided from start to finish. We believe that the customer journey does not finish once you’ve had your boiler installation and that aftercare is just as important. Let’s take a look at the aftercare that both Vaillant and Viessmann offer.

Vaillant does not have an option to speak directly to an advisor on live chat, however, they do offer an online customer form that you can submit for any issues. There is also an option to call their customer service team, yet calls are charged at 13p a minute. Aside from this, as you can see from Vaillant’s Trustpilot reviews, customers are still very happy with their services, despite not being as easy to get hold of as other brands. 

Vaillant boilers have a standard 5-year guarantee as standard. You also get up to a 10-year warranty if you purchase a new or replacement Vaillant boiler with WarmZilla. This guarantee will cover labour and parts for the length of your term. For any repairs outside of your guarantee, Vaillant offers an amazing 25% discount on repairs for all NHS Staff at present.

If you are looking for a quick fix, Vaillant does offer an Advice & Knowledge section and a boiler manuals section so you should be able to access some information regarding your boiler online. 

Viessmann also has an online enquiry form where you can submit your issues and they will then be dealt with via email. However, they also have a contact number that is free of charge for customers to call. They have split their aftercare into three departments, sales, customer service, or technical advice so that any issues can be dealt with promptly. 

Viessmann also has an FAQ section available on their website, for help with general questions as well as a support section that helps with booking your annual service or repairs. 

The majority of the Viessmann boilers come with a standard 3 -5 year warranty which can be extended to 5-7 years if installed with a Viessmann Trained Installer. However, as mentioned, when purchasing a new or replacement Viessmann boiler with WarmZilla, you get 10 years warranty.

If you find a fault with your boiler, it may be time to think about buying a new one. WarmZilla can offer you a boiler quote in just 90 seconds, providing you with a list of the best boilers for your needs. There are also boiler finance options available to help spread the cost.

Boiler finance

Boiler finance is the most popular payment option – you can spread the cost interest-free (0% APR) over 24 months or up to 10 years (11.9% APR) if you want to get those monthly payments right down. The monthly repayments on your boiler finance plan will depend on the length of term finance you select, the boiler you choose, and the deposit amount you choose to pay.


Are you thinking what I’m thinking?… Although Viessmann and Vaillant both offer solid boilers and both brands are A-rated by the EPC register, we think it’s safe to say that in the battle of Vaillant vs. Viessmann, Viessmann has come out on top!

  • Viessmann is cheaper for the same capacity boilers
  • Viessmann is slightly more efficient. Up to 98% efficient on select models
  • Viessmann offers a better warranty on their boilers
  • Viessmann boilers are technologically superior and use Inox-radial stainless steel heat exchangers. Which also makes them more reliable.
  • Viessmann is more compact, which means that both installation and servicing are a lot easier.

However, 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 thinking about getting a new or replacement boiler, but you’re unsure what boiler is best for your home, we have some blogs that may be able to help:

Or you could use our Boiler Comparison tool, which allows you to compare up to three boilers at one time, helping you find the perfect boiler for your home.

*These prices have been taken from our online survey. These prices are based on a standard terraces house with 3 bedrooms and a single bathroom. Please note that these prices are subject to change depending on your demands. 
** Prices have been taken from as an estimated price range for the system and regular boilers. Unfortunately, WarmZilla does not sell EcoFit Pure system boiler, Vitodens 200-W system boiler, or the Vitodens 100-W regular boiler.

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