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Viessmann Vitodens 100-W Condensing Gas Boiler Review

Looking for a new boiler and thinking about the Viessmann Vitodens 100-W? Good call — for most homeowners, it’s an excellent choice.

But to help you make up your mind, we did our research and came up with this quick guide. Here, we’re going to explore and review the Viessmann Vitodens 100-W boiler and compare it to another industry-leading brand — Worcester Bosch.

After reading our review, you’ll have everything you need to know to decide whether the Viessmann Vitodens 100-W is the right boiler for you.

Do You Need a Natural Gas Boiler?

First of all, you can get a Viessmann Vitodens 100-W if your central heating system uses a combi boiler, system boiler, or heat-only boiler; this product range has all 3 boiler types. So, whether you need hot water on demand, or you have a cold feed in your loft and a hot water cylinder, a Viessmann Vitodens 100-W can work; you just need to tell the installer which type you need.

Alternatively, just use this form to determine which boiler you need, the size and to get prices on screen.

Viessmann Vitodens 100 W Boiler: Overview

Here’s a few of the key things worth mentioning about the Viessmann Vitodens 100-W gas boilers: 

  • The extended warranty can cover you for up to 10 years
  • It’s suitable for properties with up to 3-bedrooms
  • Vitodens 100-W is Boiler Plus compliant
  • The boiler is smart thermostat compatible
  • Class A efficiency rating
  • It provides outputs ranging between 4.7kW and 35kW

According to Viessmann, it’s their best selling boiler. So, if you’re looking for a boiler from their brand, this is the one you should be looking at.

Product Warranty and Reliability

Although when most people think boilers, they think Worcester Bosch, Viessmann are always a brand worth mentioning. Both homeowners and Gas Safe engineers alike consider Viessmann to be one of the most reliable boiler brands on the market.

And, that’s backed up by their warranty. Many boilers on the market today come with warranties as short as 2 years. With the total cost of installation starting at around £2,000, that’s not much of a guarantee.

Minimum Acceptable Warranty Term for a Boiler

If you’ve read any of our other reviews, you’ll know we always suggest a minimum warranty of 5-years. And of course, with a (maximum) 12-year warranty, the Viessmann Vitodens 100-W blows that figure out of the water.

If Viessmann have that kind of confidence in their product, then so do we.

One of the reasons the Viessmann warranty is this long is due to the stainless steel Inox Radial heat exchanger. When a heat exchanger fails, it can cost over £450 to replace. But, a stainless steel heat exchanger is likely going to last much longer than an aluminium one.

Alternatives to the Viessmann Vitodens 100-W Boiler

There are plenty of alternative brands offering a similar warranty. For instance, you can get a Worcester Bosch boiler with a similar warranty and at a similar price. Use this clickable form and you’ll get prices on screen within a matter of minutes — for Viessmann and other top brands.

Heatable boiler installations

*In order to get the 10-year extended warranty, the boiler needs to be fitted by a Viessmann Accredited installer. Without accreditation, your installer can only offer 5-years as a warranty.

Control Vitodens 100 Noise

Boilers — especially older ones — can be incredibly noisy. Typically, that’s a combination of a worn fan and a worn out pump. Together, they can make a heck of a noise.

Viessmann have focused on making the Vitodens 100-W as quiet as possible, and they’ve done this by setting up the internals of the boiler so that the fan can do it’s job at an incredibly low speed.

The fan in your boiler helps vent dangerous gases out of the flue, so it’s not just a case of turning it down, the whole boiler has to be designed to accommodate a fan running at a low speed. That’s something Viessmann have achieved, making the Vitodens 100-W extremely quiet in the process.

Ease of Use (LCD Touchscreen Display)

One of the first things you’ll notice with the Vitodens is that it’s got a sleek-looking LCD back-lit touch screen display. The latter doesn’t just add to the styling of the Vitodens; it’s practical, too.

Using the touchscreen display is a breeze in poorly lit rooms, and even in the dark.

Energy Efficiency and Money Savings

Although the initial outlay for a new boiler is something you could do without, there is a silver lining. Old boilers can have as little efficiency as 60%. And a boiler like the Viessmann Vitodens 100-W is 94% efficient.

With heating accounting for around 55% of bills, that’s going to result in a huge cash saving. In fact, the Energy Saving Trust recently conducted a study that showed huge savings of up to £840 per year when a new boiler was installed.

Ironically, most companies now offer boiler finance, with packages as low as £25 per month, which means the boiler basically pays for itself (and then some), simply due to energy savings. By the way, if that’s the route you’re taking, there’s a guide to getting new Viessmann boilers on finance here.

Of course, higher energy efficiency also translates into lower CO2 emissions — another great selling feature, especially if you’re trying to reduce your carbon footprint.

Smart Thermostat Compatibility

Smart thermostats are part practical (energy saving and convenience), and part fashion; they look great.

With the Viessmann Vitodens 100-W, if you want to hook up a smart thermostat, you’ll have no problem doing so. You’ll be able to get the tado° installed with your boiler, and then install the tado° app on your smartphone to control it.

Vitodens 100-W (Reviews)

Although finding trustworthy consumer feedback on boilers isn’t as easy as pulling up reviews on Amazon, there are homeowner reviews out there. One of the best places to check out is Reviews.co.uk.

viessmann vitodens 100-W reviews

Currently, Viessmann have over 350 reviews, with an average rating of 4.5 stars. More importantly, 89% of people would recommend Viessmann as a brand.

What’s more, Viessmann Vitodens 100-W has also received the prestigious Which? Best Buy award for several years in a row.

Viessmann 100-W vs Worcester Bosch: Prices

Viessmann are a premium brand, and like all premium brands, a similar price tag is attached. Currently, you should expect to pay around £1,100 for the Vitodens 100-W combi boiler. Including all parts (flue, pipework, magnetic system filter and so on), as well as labour, the 30kW is likely to cost around £2,300 to get installed; give or take.

You can check your own prices here.


As a direct comparison, you’d be looking at something like the Worcester Bosch Greenstar 4000. Typically, that’s going to cost around £1,200, so around £100 more, without the cost of boiler installation.

But, there is a way to get Worcester boilers cheaper, too — also with Heatable.

Worcester Bosch Greenstar 4000

So here you have it, you can get a comparable quote for a Worcester and Viessmann combi boiler back to back.

You can get quotes from local installers for a Viessmann Vitodens here.

Or, if you’d prefer a Worcester boiler, you can get a fixed price online here, from Heatable.

Viessmann Vitodens 100-W: Review Verdict

If you’re after a highly efficient new boiler for your mid-sized property, the Viessmann Vitodens 100-W is an attractive option. Not only does the model come packed with all of the latest user-friendly features and reliable parts, but it’s also relatively affordable — as far as premium boiler models go.

And, on top of its outstanding product quality, the Vitodens 100-W is actually also compact — you can fit this boiler into a kitchen cupboard and save plenty of space at home.

FAQs About the Viessmann Vitodens 100-W Boiler

Below, we’ll take the time to answer a few questions we commonly hear about the Vitodens 100-W.

Is Viessmann Vitodens 100-W a combi?

The Vitodens 100-W gas condensing boilers are available as combi boilers, system boilers, and heat-only boilers. Be sure that you ask for the correct boiler type when you request your installation.

Not sure which boiler type is most suitable for your home? You can read our guide to different boiler types here.

How long are Viessmann boilers guaranteed for?

It depends on the model, whom you get to install the boiler, and whether you pay to upgrade the warranty. Below is a table with Viessmann boiler warranties:

Registered within 30 Days of Installation Non-Viessmann Trained Installer Viessmann Trained Installer Chargeable Upgrade Options for Viessmann Trained Installers
Vitodens 050-W 3 years 7 years 10 years ( 3 years + 7 Years)
Vitodens 100-W 5 years 5 years 12 years ( 5 years + 7 Years )
Vitodens 111-W 5 years 5 years 12 years ( 5 years + 7 Years )
Vitodens 200-W (up to 35 kW) & 222-F 3 years 5 years 12 years ( 5 years + 7 Years )
Vitodens 200-W from 49 to 150 kW 3 years 5 years 10 years ( 5 years + 5 Years )

Note that when you buy through Heatable, you’ll automatically get a 10-year warranty as standard.

How do I reset my Viessmann Vitodens 100?

It depends on how old your Vitodens 100-W model is. Newer Vitodens 100-W boilers have a reset button marked “R” on the digital display, whilst older models have a “RESET” setting on the control knob.

If you have a newer Viessmann, you can reset it by pushing and briefly holding the “R” button on the display. On the other hand, if you’ve got a Viessmann with control knobs, simply turn the knob to the “RESET” position; doing so should reset your appliance.

Note that reseting a boiler before you fix the underlying issue that caused it to stop working is only a temporary fix. For example, if your boiler has low pressure, you should first figure out why this is the case and perform necessary repairs before attempting a reset.

Is Vitodens 100 a condensing boiler?

Yes, Viessmann Vitodens 100-W is a condensing gas boiler. This means that the boiler is designed to capture latent heat given off by the escaping exhaust gases with a secondary heat exchanger. This technology allows condensing boilers, such as Vitodens 100-W, to operate more efficiently than non-condensing boilers.

One thing to note here is that condensing boilers will only operate in the condensing mode — i.e. at peak efficiency — when the return water temperature is 54°C. This means that the flow temperature should not be set above 70°C.

What’s Next?

Thanks for reading our Viessmann Vitodens 100-W boiler review. We regularly write up how-to guides and boiler reviews, so bookmark our homepage. Feel free to use our search bar to find answers to any questions about Viessmann or other boiler brands you might have.

Or, leave us a comment below and we’ll do our best to get back to you as soon as possible.




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