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Viessmann Vitodens 100-W Boiler Review

viessmann vitodens review

Viessmann are a long-established German company trading internationally specialising in heating and refrigeration systems. Here in the UK, they’re best known for their comprehensive range of boilers installed in millions of British homes.

With over 100 years of experience in the home heating sector, Viessmann has a wealth of knowledge and experience when it comes to providing customers with cutting edge heating technology

Their firm focus in the British market is on manufacturing boilers, solar thermal systems, heat pumps, and HVAC systems.

Their name is synonymous with quality products and they have won numerous sustainability awards for their progressive approach to environmental impact. 

In this article on best-selling Viessmann Vitodens 100-W boiler, we examine:

  • Which?’s very high score for the range
  • how HomeSage scored the two boilers in this range
  • our full review of the Viessmann Vitodens 100-W
  • Viessmann Vitodens 100-W FAQ
  • getting yourself the best deal on a Viessmann Vitodens 100-W

If you’re thinking of replacing your current boiler, it pays to shop around and get a selection of quotes for the job you require. 

Here at HomeSage, we want to make this as easy as possible for you.

If you fill in your details on our form, we will get in touch with 3 or 4 local, trusted and Gas Safe registered boiler installers in your area to contact you directly with a competitive quote. 

And if you want to read more about Viessmann in general, we have a Viessmann boiler manufacturer review that can help!

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The Viessmann Vitodens 100-W Combi Boiler is a Which? best buy

Which? is a consumer advice and information website which…

  • champions the customer and 
  • aims to raise standards of businesses

…to make sure the public get quality products and value for money.

They award products and companies with their ‘Best Buy’ award if they believe a product will have a significant and positive impact on consumers’ lives.

The ‘Best Buy’ award was developed in 2007 and it has been awarded in multiple sectors from retail to cars and banking to home appliances – including boilers.

As of 2019, Viessmann’s Vitodens domestic boilers have received the converted ‘Best Buy’ award from Which? for three consecutive years

Here at HomeSage, we have developed our own boiler scoring system to give our readers even more information when they are deciding on their next boiler investment.

On our 100% unique ranking charts, we rated a range of factors and features of the boilers to give you a thorough understanding and included the following in our metrics:

  • the length of boiler warranty included
  • the cost of the boiler
  • the energy efficiency level and,
  • the amount of reviews and ratings on Trustpilot.

Reviewing the Viessmann Vitodens 100-W 30kW boilers

What is a combi boiler?

The Viessmann Vitodens 100-W 30kW is a combi boiler.

Combi boilers draw water directly from the mains supply and it heats that water as it passes through the boiler using an internal heat exchanger.

Combi boilers don’t require any external water storage tanks unlike regular and system boilers.

They are usually wall-hung units and come with outputs and water flow rates.

This choice means that you can choose the most suitable one for your property and save money annually.

Combi boiler outputs

It’s necessary to choose a combi boiler with the right output level for the size of your home – specifically the number of radiators, rooms and bathrooms that you have.

Choosing a boiler with an output too low would result in not enough power for your hot water needs.

Conversely, choosing a boiler with an output which is too high results in you paying too much for your energy bill. Your gas bill should always go down when you install a new boiler.  

The boiler’s output also lets you know how much it will cost to run it per hour.

To work that out, the calculation you need is the kW multiplied by the cost of a unit of fuel.

For example, a gas combi boiler with an output of 18kW using gas at 4p per unit would be 18 x 0.04 = £0.72 per hour. 

Viessmann Vitodens 100-W 30kW Combi Boiler (79.01%)

Make and ModelViessmann Vitodens 100-W 30kw Boiler
Efficiency Rating88.90%
Band RatingB
LPG Compatible?Yes
Parts and Labour Warranty in months60
Heat Exchange Warranty in months60
Output kW30
MountingWall Mounted
Flow Rate in litres per second12
Price from£1,075
Price to£1,115
ERP WaterA

As you can see, the Vitodens 100-W 30kW has a good energy efficiency score of 88.90% which places it at the high end of a SEDBUK ‘B’ rating, meaning it will save you money compared to less efficient models.

The price tag is around average for boilers of this output and it comes with a warranty of up to 10-years

The Vitodens 100-W 30kW is one of the manufacturer’s best-selling boilers. 

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Viessmann Vitodens 100-W 35kW Combi Boiler (78.82%)

Also from the award-winning Vitodens range is the slightly more powerful 100-W 35kW combi boiler.

This boiler would be well suited to larger properties that have 4+ bedrooms, more than one bathroom and require greater hot water power. 

Make and ModelViessmann Vitodens 100-W 35kw Boiler
Efficiency Rating89.30%
Band RatingB
LPG Compatible?Yes
Parts and Labour Warranty in months60
Heat Exchange Warranty in months60
Output kW35
MountingWall Mounted
Flow Rate in litres per second14
Price from£1,150
Price to£1,200
ERP WaterA

The results show a very slightly lesser total score of 78.82% but a marginally better energy efficiency level, however still coming in with a ‘B’ rating. 

As with the lower output model of this boiler, it comes complete with a warranty of up to 10 years which is a generous amount of time and will provide extra peace of mind. 

Please note these results are relevant to the combi boiler style in this range. 

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The Viessmann Vitodens 100-W Combi Boiler reviewed

Key features

There are many reasons this boiler has won the prestigious ‘Best Buy’ Which? award for three years running.

Let’s take a look at the functions that have been designed to keep your home warm and cosy:

  • Up to 89% of the fuel used is converted into heat – this is a highly efficient machine that only loses 11% of energy in running itself correctly, and the higher the efficiency rating, the lower your heating bill.
  • Compact design and low weight – measuring in at 700mm x 400mm x 350mm this is a compact boiler which can be tucked away out of sight for minimal aesthetic disruption. It’s low weight also allows for an easy installation that your engineer will thank you for.
  • Quiet operation thanks to low fan speed – there’s nothing worse than a boiler that goes bump in the night and, thanks to Viessmann’s cutting edge technology, this boiler is an ultra-quiet system which you’ll barely hear working. 
  • High quality stainless steel Inox-Radial heat exchanger – this durable and long-lasting internal component is one of the secrets behind this powerful boiler and works to optimise your heating throughout the day and night.
  • Up to 10 year extended warranty available – this boiler actually comes with a 5-year warranty out of the box as standard but you have the option to top this up to 10-years if you install it through a Viessmann trained engineer and keep up to date with your annual services.
  • User friendly Backlit LCD Touch screen for easy operation – Viessmann makes boilers designed to be simple for every homeowner to use. The backlit LCD screen means you can see your boiler status at a glance even in a dark cupboard.
  • Class A rated for energy efficiency – one of the main draws of this combi boiler is its grade ‘A’ on the SEDBUK scale. This guarantees a much lower heating bill for you and the knowledge your boiler is spending the majority of its energy heating your house as opposed to running itself.
  • Low CO2 emissions for reduced environmental impact – we should all be trying to reduce our carbon footprint and this boiler can help you do that with its low CO2 emissions. 
  • Optional extras available – room thermostats, the option to control your heating through the tado° app and wireless technology mean this boiler makes your life easier and its simple to tune it into your favourite settings.
  • Available in outputs from 4.7 to 35 kW – no matter what size property you have, there is an output suitable for your central heating and hot water needs so you can find a version of this boiler that will suit you perfectly. 
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One of the benefits of a combi boiler is that they are compact, can be installed in a range of locations and don’t require changes to the layout of your property. 

The Viessmann Vitodens 100-W is 700mm in height, 400mm in width, and 350mm in depth so, measurement permitting, it can be fitted in a standard kitchen unit away from your line of vision. 

You could also consider installing this in your garage or utility room if you don’t have room in the house. 

Because it has in-built frost protection, you don’t need to worry about any frozen pipework shold you choose to install it in a colder part of your property..

Extra benefits

Alongside the featured specifications as detailed above, there are a number of benefits which may sway you into purchasing this popular boiler model.

The Vitodens 100-W is a technically advanced boiler which boasts simple, user-friendly controls through its LED backlit screen

The control panel is touchscreen and easy to follow so, even if you don’t have a wealth of boiler knowledge, you should have no issues setting your controls for heating and hot water on a regular timer.

This boiler features a weather compensated operation which makes it suitable to be used in all climates and seasons effectively.

Make sure to ask your boiler installer about the additional extra of an outdoor sensor which indicates weather changes in order to provide you with the optimum level of heat at all times. 

The Vitodens 100-W makes excellent use of a modulating cylinder burner which allows it to function in conjunction with other boilers in one chimney system.

This flexibility makes it perfect for businesses or larger properties as well as a traditional home

Where is this boiler made and how long will it last?

The Viessmann Vitodens 100-W is designed and manufactured in Germany so you can expect the high level of engineering and internal component quality and craftsmanship associated with this country. 

They have been produced to be exceptionally long-lasting and reliable so you don’t have to worry about potentially replacing your boiler after a matter of a couple of years.

With regular annual services and maintenance, your boiler should last you a good decade or two or possibly even more.

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How much will a Viessmann Vitodens 100-W cost me?

It’s not just the price of the boiler you need to consider when you’re updating your heating system.

You also need to consider the cost of the installation and any prep work the engineer might need to do to your pipework or existing radiator system

We always recommend speaking to a selection of boiler installer specialist firms to find out exactly what hidden costs you may incur during installation as these can creep up on you unaware.

Viessmann is a company internationally known for their affordable price tag despite their high-quality products

You can be sure you are getting a substantial piece of kit for the money you’re shelling out. 

Much like the other models from Viessmann, this is a fairly priced boiler which makes it accessible to many people including those on a budget

Depending on who installs this boiler for you, you may be able to purchase and install for just under £2,000 however this will vary from property to property. 

The national average for boiler price and installation is generally over £2,000 so this model does provide good value for money. 

If required, you can speak to your boiler installer to discuss any optional extras such as the outdoor thermostat for the weather compensation system, or to increase the length of your warranty. 

Why should I buy this boiler?

Viessmann is a trusted and reliable international manufacturer of high-quality boilers and, with their excellent track record of customer service, there is little to find fault with this product.

The compact nature of this boiler means it will sit well in any property with minimal disruption whilst being installed and serviced.

As it is a front-access boiler, the engineer shouldn’t make too much mess whilst maintaining and installing it.

The Vitodens 100-W does offer very good value for money with a high level of technology to make your life that little bit easier.

It’s also ultra-quiet to avoid any sound interruptions in your home. 

The price point of this boiler is excellent compared to other manufacturers’ products on the market.

Because it is jam-packed with extra features, we are certain of its continuing popularity for years to come.

Get the best deal on a Viessmann Vitodens 100-W Combi Boiler

Fill in the form at the top of the page and we’ll contact three to four local Gas Safe installers to quote you.

Many HomeSage users have reported to us a difference of up to 54% between their highest and lowest quotes so it always pays to shop around.

Our service is free and you’re not obliged to accept any offer made by one of our partner installers.

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Andy is one of the HomeSage founders and an occasional content contributor. His love for boilers is only just outweighed by his love for football.