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Last Updated on November 22, 2023

Viessmann Vitodens 100-W Boiler Review

The Viessmann Vitodens 100-W is Viessmann’s best-selling gas condensing boiler, one of the most popular boilers we install and has been awarded a Which? Best Buy three years in a row.

For 2021, the Viessmann Vitodens 100-W has been updated with all new features.

In this review, we have taken a look at the new 2021 version of this boiler in detail and offered our thoughts. From its reliability and longevity and how user friendly it is.

Viessmann Vitodens 100-W Technical Specification:

Manufacturer Viessmann
Model Vitodens 100-W Gas Boiler
Condensing Yes
Efficiency Rating 94%
Energy Efficiency Class A Rated
LPG Compatible Yes
Warranty Up to 10-year comprehensive warranty when installed by a Viessmann trained installer
Weight 38kg
Dimensions 700mm (Height) x 400mm (Width) x 350mm (Depth)

Key Features:

  • High-quality stainless steel Inox-Radial heat exchanger
  • Environmentally responsible MatriX-Plus cylinder burner which extends the boiler’s service life and reduces CO2 and NOx emissions
  • Lambda Pro automatic combustion control for maximum efficiency at all times
  • Backlit LCD touch screen display
  • Integrated Wi-Fi
  • Pressure release valve and condensate combined for easy installation
  • Compact design and low weight
  • Quiet operation with low fan speed
  • Low CO2 emissions for reduced environmental impact
  • Modulation range up to 1:10
  • Constant temperature control and weather compensated operation (an outside temperature sensor is available for weather compensation)
  • Ready for 20% hydrogen mix in the gas supply
  • Up to 10 year extended warranty available
  • LPG conversion kit available
  • Compatible with Viessmann’s Vitoguide software, and ViStart and ViCare app
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Our thoughts:

Which? Best Buy

The Viessmann Vitodens 100-W has surged in popularity since first being awarded Which? Best Buy status in 2017.

The Vitodens 100-W’s Best Buy status was first awarded based on feedback from 219 registered Which? Trusted Traders heating engineers and 9,610 domestic customers. This feedback covered the experiences of the boiler owners and the views of the installers in regard to the ease of servicing, fixing a common fault, availability of parts and spares, build quality and recommendations.

Having also received Which? Best Buy status in 2018 and 2019, the boiler has been noted for its reliability each time.

Integrated Wi-Fi

Launched in April 2021, the new Vitodens 100-W notably now comes with integrated Wi-Fi. This along with the 100-W’s new control platform makes commissioning and servicing the boiler easier. From an engineer’s perspective, this means that they are now able to monitor and make adjustments to customers’ boilers remotely using the Vitoguide software. This shortens services processes and improves customer service by showing the engineer the status of customers’ systems at a glance. Here, they are able to see fault messages instantly and respond to any issues promptly.

For the engineer, the compatibility with Vitoguide also makes commissioning the boiler easier and provides a step-by-step guide covering time programmes, heating circuits, heating curves, DHW and the circulation pump.

For the end-user, the integrated Wi-Fi means that the Vitodens 100-W is now fully compatible with the battery-powered, RF-connected ViCare Thermostat. This means that the boiler can not only be controlled using the boiler’s large seven-inch colour touchscreen, it can also be controlled using this device whilst at the property and not only that, it can also be controlled wherever you are in the world using the ViCare app on a smartphone or tablet – all without the need for third-party controls.

The ViCare app provides the Vitodens 100-W with the following functionality:

  • Information on the current operating status
  • Quick adjustments to the heating system
  • Time programmes for heating and hot water, by zone

Reliability and efficiency

Reliability and efficiency continue to be two of the standout qualities of the Vitodens 100-W. This is enhanced by the new MatriX-Plus burner and new Lambda Pro automatic combustion control in the 2021 Vitodens 100-W range. These technologies ensure low fuel consumption with low NOx and CO2 emissions.

New for 2021 is the Vitodens 100-W’s increased modulation range, with the boiler now modulating 1:10 (32kW).

Whilst the new Lambda Pro automatic combustion control ensures reliable and clean operation even when the gas quality fluctuates by detecting and adjusting to the gas type. In addition to this, it offers future-proof ability with reliable and efficient compatibility if the seemingly possible happens and the UK gas grid supplies a blend comprised of 80% natural gas and 20% hydrogen.

10-year comprehensive warranty

The reliability of this boiler is then backed up by the up to 10-year comprehensive warranty available.

For 2021, the mechanical design of the Vitodens 100-W has reduced the number of spare parts needed for routine maintenance by about 50%. This means routine maintenance and servicing is made easier.

Whilst with a 94% efficiency rating, this boiler is one of the highest efficiency condensing gas boilers available to purchase in the UK currently. It also sits at an attractive price point compared to other boilers available in the UK. However, this is not a budget boiler option.

Viessmann is one of the most technologically advanced boilers manufacturers in the world and the Vitodens 100-W benefits from the following as a result:

  • 94% efficiency
  • Lightweight construction
  • Compact in size
  • Very quiet operation, with noise levels of just 35dB

A major contributor to Viessmann being able to keep the cost of the Vitodens 100-W down is the fact that the entire boiler and all of its components are manufactured at Viessmann’s headquarters in Allendorf, Germany.  A centre of excellence, at their Allendorf site, Viessmann has focused on the efficiency and innovation of their gas-fired wall-mounted condensing boilers. It is here that they have strived to improve their product quality and performance, recognising their past mistakes and issues with obtaining parts, and have worked hard to rectify this.

Viessmann’s hard work has paid off and this shows with the quality of the Vitodens 100-W.

Parts and service availability

As mentioned above, one of the earliest complaints Viessmann boilers faced was the non-availability of parts.  This is something which has been rectified by investing in their UK headquarters in Telford, Shropshire.  Now all Viessmann boilers, kits and parts are available at all Plumbases stores across the UK.

Whilst in the rare event of a problem, a Viessmann engineer can be at your doorstep within 24 – 48 hours.

Innovative technology

Unlike many other boiler manufacturers supplying boilers to the UK market, Viessmann utilises a stainless steel heat exchanger in their boilers rather than one constructed from aluminium. A patented product called an Inox-Radial stainless steel heat exchanger, this is manufactured in-house by Viessmann and offers the following benefits:

  • Constructed from Inox, the highest grade of stainless steel available
  • Increased efficiency, reliability, durability and corrosion resistance compared to aluminium
  • The technology is a major contributor to the 94% efficiency rating achieved by the boiler
    10-year warranty

CFS (Combined Flue System)

If you are looking at renovating or modernising your property, the Viessmann Vitodens 100-W condensing boiler makes for an ideal replacement for older boiler systems.  Using a Viessmann CFS (combined flue system) means multiple boiler flues can be routed to exit from one exit point, whether it’s through the roof or through the wall.

Combined Condensate & PRV

Viessmann’s entire boiler range also has combined PRV (pressure relief valve) and condensate connections that can also be routed into the CFS, and one single drain at the base of the system is all that is required to remove the condensate, without the need of ugly pipes protruding through the external walls.

For more detail on this useful aspect of your heating system, please read our ‘What is a condensate pipe?‘ blog post.

On top of winning “Which? Best Buy” awards, pumping out a whopping efficiency of 94%, dominating the European market and having our engineers singing its praises, our verdict is pretty straightforward.

With the futureproof technologies added to this already highly popular boiler, you simply cannot go wrong with choosing the Vitodens 100-W in 2021

What’s more, if you get the boiler installed by a Viessmann Trained Installer like Boilerhut, you will not only have your boiler installed to the highest standards, you will also benefit from an extended 10-year warranty.

As the internal components are built to last, choose the Vitodens 100-W and we expect you to be able to enjoy trouble-free winters for the next decade at the very minimum.

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