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Viessmann Vitodens 100-W boiler review

Viessmann Vitodens 100 Review

**Updated brand new 2021 model**

Viessmann Vitodens 100-W boiler review Compare Boiler Quotes

The Viessmann Vitoden 100-W is already a multi-award winner, having been selected as a Which? Best Buy for three years running.

With this in mind when Viessmann announced that they were releasing a new and improved version of the 100-W in 2021, then we had no doubt that it would immediately become one of the most popular boilers in the UK, and we were right!

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New look futureproof Hydrogen ready Viessmann 100

Viessmann Vitodens 100-W boiler review Compare Boiler Quotes

It has since been given a facelift and some future-proof technology to send it to the top of the list in terms of value and longevity. With Hydrogen ready capabilities and built-in WiFi, this is the boiler for the future.

Get a price on a Viessmann 100-W using this free online tool – Click here

In this review, we’re going to delve into all the functionality that makes the Vitodens 100 W such a popular choice.

Key facts and figures

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Here’s our quick summary of the key information for the Vitodens 100 W

  • Energy efficiency level of 94%.
  • ErP classification of ‘A.’
  • Weight 33kg.
  • Height of 700mm, a width of 400mm and depth of 360mm.
  • Three to ten-year warranty (12-years with Boiler Central).

Viessmann 100-W boiler models

The Vitodens 100-W is available as both a combi and system boiler. The combi is available in three different power outputs, 26kW, 30kW and 32kW, with corresponding flow rates of 10 l/min, 12 l/min and 14.5 l/min.

The system boiler is available in four sizes, 11kW, 19kW, 25kW and 32kW.

Viessmann Vitodens 100-W

Combi Boiler

Output kW


Gas Condensing


Energy Efficiency Rating


ERP Heating


ERP Water



700x400x350mm (HWD)

Stainless Steel Heat Exchanger



Wall Mounted

Flow Rate


Heat Exchanger Warranty

12 Years

Parts and Labour Warranty

12 Years

LPG Compatible


Hydrogen Ready?


Boiler Price With Installation

From £2,250

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Do I need a 100-W system boiler or a combi boiler?

The key deciding factor in the combi vs system boiler debate all comes down to your demands on the hot water supply.

If your demand is high, so you have two or more bathrooms, then a system boiler is likely to be the best option. If you have one bathroom, then the combi is going to meet your needs.

Read this guide on the best system boilers on the market right now.

Viessman 100 system boilers

This all comes down to the fact that the system boiler heats the water and then stores it in a cylinder.

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That then allows it to have large volumes of hot water ready to go and to be able to supply two bathrooms at the same time. Combi boilers heat water on demand. So, when you turn on the hot water tap, it then heats the water and sends it straight to the outlet. 

Read more: Best combi boiler guide

Disadvantages of the system boiler mainly come from the space needed for the cylinder and that there may be a long wait for hot water if the pre-heated supply has been used up.

On the combi boiler, if you turn on the hot tap when someone is having a shower, they may be met with a deluge of freezing cold water.

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Viessman Vitodens 100-w Combi boiler

If you’re a fan of a power shower, then with a combi boiler, that’s going to depend on your mains pressure. If that’s an essential requirement, you should check the mains pressure in your area before arranging the installation.

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But if this isn’t you then the Vitodens 100-w combi boiler could be perfect. it’s powerful enough to heat plenty of radiators in large homes and get your hot water steaming in a matter of seconds.

Making the right choice is so important in ensuring that you get the supply of hot water that you need.

So it’s worth taking a moment to read through our article on boiler types before you place your order.


Key features of the Viessmann Vitodens 100-w boilers

Integrated Wi-Fi

A new feature for the 2021 Vitodens 100 W model is the integrated Wi-Fi. This brings huge benefits to how you can both monitor your boiler and manage the heating system on a day-to-day basis.

It’s also a firm favourite with the heating engineers because they can now monitor and adjust the boiler remotely via the Vitoguide software.

Now, if there is a problem with the boiler, the engineer can log into the system and instantly see the error codes and understand what the problem is.

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If it can’t be fixed remotely, then the engineer can arrive at your home with all the required spare parts making repairs quick and easy.

As well as resolving issues, Vitoguide also speeds up the installation process providing the engineer with step-by-step guides and reporting to ensure that everything is working as it should. 

For the homeowner, the integrated Wi-Fi means that you now have several choices as to how you control the Vitodens 100-W.

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The seven-inch full-colour LCD display on the new control panel provides seven different pieces of information on how the boiler is operating.

Designed to be easy to use and understand, the touch screen has a discreet black panel design.

ViCare app

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The Vitodens 100 W is fully compatible with the ViCare app. Now, no matter where you are in the world, you can control and make adjustments to your home heating. Going to be home early?

No problem, you can adjust the timing so that the heating is on thirty minutes before you arrive home. On holiday but want to check that everything is working okay?

You can do that too, and if there are any issues, then you have a direct link to an engineer to provide advice.

Compatible with the Tado smart thermostat

If you’re looking for even more control of your system and the opportunity to save up to 31% on your energy bills, then you might have considered a smart thermostat.

The Vitodens 100-W is compatible with Tado, one of the top-selling UK smart thermostats and which is operated via an app on your phone.

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Tado takes heating control one step further. It can still do all the scheduling and reporting, but it also notifies you when it recognises that there’s no one home and the heating is still one.

It’ll even let you know when you’re left a window open, and the heating is still on. Then if the humidity is too high and there’s a risk of mould, then it’ll advise you to open up a window to get some fresh air in there.

Designed for reliability and efficiency

Viessmann already has a strong reputation for the reliability of their product range, and the Vitodens 100-W is no exception.

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This is a manufacturer who takes an ‘all-in’ approach to their boilers; all of the parts are manufactured by Viessmann, and that means that they’ve been designed to work hand in hand with each other.

The cost of a new boiler from the Viessmann 100-W range starts from £2,250 fully fitted.

Some of the key Viessmann technologies that you’ll find in the Vitodens 100-W include:

MatriX-Plus burner

This new burner reduces fuel consumption by carefully regulating heat production depending on your current needs. It also has automatic combustion control and produces 40% fewer emissions.

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Made from a special stainless steel, the MatriX isn’t sensitive to high temperatures and so provides reliable performance combined with a long working life.

Lambda Pro Plus combustion control

The Lambda Pro Plus ensures that whether there are gas type changes, fluctuation in gas quality or changes in operating conditions, the Vitodens 100 W will still provide a reliable source of hot water.  The Lambda Pro Plus also reduces emissions meaning that cleaning of the system is needed less frequently.

The Lambda Pro Plus speeds up the installation proves because it automatically undertakes the adjustment work that’s usually required.

This combustion control system can detect the gas type and automatically adjust the Vitodens 100-W to work in the most efficient way possible.

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Stainless steel Inox-Radial heat exchanger

The material used for the heat exchanger makes all the difference not only to the longevity of the heat exchanger but also to efficiency levels.

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The Inox-Radial heat exchanger is made from stainless steel, resulting in a corrosion resistance just not possible with other metals.

It also means that there is virtually no heat loss giving efficiency levels that were unthinkable a few years ago.

Hydrogen ready (H2) Viessmann 100

The EU has committed to reducing CO₂ emissions to zero by 2050. But this can only be achieved without using fossil fuels.

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One of the energy sources which may provide an alternative to our current use of natural gas is hydrogen. While there are still some logistical issues to overcome, there are still expectations that this greenhouse gas neutral energy source will be a key source of fuel for our homes.

Our popular article on hydrogen boilers is worth a read to see how hydrogen will be used in the coming decades.

The first step towards this is introducing a mix of 80% natural gas and 20% hydrogen into the gas grid. It’s then hoped that 100% hydrogen will become a possibility by the mid 2030s.

That all means that it’s incredibly important that any boiler replacement that you purchase is hydrogen ready.

Then, you’ll know that when the 20% mix is launched, your boiler will need no technical adjustments or new parts to carry on working as normal.

The Viessmann 100-W is certainly future proofed by already being able to take a 20% hydrogen mix.

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Modulation of up to 1:10

When a boiler can modulate, it means that it can turn down the power output. So, if you have a 20kW boiler but you only need 10kW to meet your heating needs, then the boiler can turn down its flame by 50%.

Without modulation, the boiler would output 20kW for five minutes and then switch off for five minutes.

The Vitodens 100 W has a modulation ratio of 1:10. That means that it’s able to operate at just 10% of its maximum power output. So if you choose the 30kW model, then with modulation, it could function at just 3kW. It’s generally agreed that the larger the ratio, the better and with many manufacturers only achieving modulation of 1:6, Viessmann’s 1;10 is an impressive market leader.

What are the benefits of boiler modulation?

There are two main benefits of boiler modulation, a reduction in wear and tear, and improved efficiency

Reduce wear and tear

When your boiler turns off, it causes several mechanical processes.

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There’s the fan coming to a halt, the gas valve closing and the pump may also stop.

With each component having a lifespan for the number of times it can be expected to turn on and off, you’ll want to avoid unnecessary stoppages to extend the life of your boiler.

Then along with the stopping and starting, there’s also the fact that the boiler will be running hotter and then cooler.

This then means that all the components will also expand and contract. Every time this happens, it increases both the stress on the boiler and the likelihood of a breakdown.

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Traditional boilers didn’t have the ability to modulate. That meant that they were either on at full capacity, or they were off.

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When you consider how long it takes for a boiler to warm up and then shut off when it’s at its warmest, then you can see that this isn’t the most efficient way for a boiler to operate

When a boiler has full modulation ability, then it can run longer but with fewer on and off cycles and at lower fire rates. In turn, the efficiency levels are much improved.

Viessmann Vitodens 100-w Warranty

The Vitodens 100 W comes with different warranty levels depending on whether you decide to take out extended cover at an additional fee.

As a basic level of cover, the 100-W comes with a five-year warranty.

Interestingly, Viessmann has decided to offer the full five years cover even if you don’t use a Viessmann trained engineer to carry out the installation.

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For example, on the Viessmann 050-W, there’s only a three-year warranty on offer in that situation. But that said, do make sure that the engineer is gas safe registered so that you know they have the skills and qualifications to carry out the installation safely.

If you purchase your Vitodens 100-W through Boiler Central, then you’ll be able to benefit from a massive 12-year warranty.

That gives you incredible peace of mind, knowing that you don’t have to worry about finding an engineer to carry our repairs nor unexpected repair bills.

Do though make sure that you keep up to date with the annual servicing of your boiler; all warranties require this to take place for your cover to be valid.

Viessmann 100-W review – Final verdict

We loved the Vitodens 100-W even before it was relaunched in 2021. So, to then have even more functionality combined with improved systems, then what’s not to love!

Choosing the right heating system for you and your home can be stressful. There are so many manufacturers to choose from, let alone all the different models and boiler types.

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That’s when getting professional and personalised advice is key to making the right choice.

Getting a new boiler quote is the first step to having all your heating and hot water problems solved!

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What our customers think

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Would recommend

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On the day, they came on time. Lovely people, they kept everything clean. Explained everything to me. No mess, kept me informed.

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Great experience - quick to arrange, easy to work with the very responsive online team and all installed faster than expected.

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