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Last updated: 22nd February, 2024


Are Viessmann Boilers Efficient?

Are Viessmann Boilers Efficient?

Key takeaways

  • Viessmann are one of the leading boiler brands in Europe, with performance and efficiency being the ethos of the brand.
  • ErP is the standard measurement of a boilers efficiency, all Viessmann Vitodens boilers are A rated.
  • Viessmann still believe in their expert engineering, having been designing premium boilers since 1917.

Viessmann boilers are some of the most well known and popular boilers on the market, efficiency is a key part of any modern boiler's capabilities, are Viessmann up to the task of heating your home?

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In this blog we’ll be taking a look at Viessmann boilers, in particular their top selling vitodens range and its premier model, the Vitodens 100-W.

Viessmann Vitodens

The Vitodens family is Viessmann’s most popular range of combi boilers. Apart from their premium performance capabilities, Vitodens combi boilers are renowned for their energy efficiency, smart technology and ease of use, the Vitodens range boasts an elite level of heating and hot water production, all the while being extremely compact!

Modern Boilers 

Modern boilers are much more energy-efficient than older models. They use less fuel to generate the same amount of heat, which means you can save money on your energy bills. According to the Energy Saving Trust, replacing an old boiler with a new A-rated boiler could save you up to £315 per year on your energy bills. This means that over time, your new boiler could pay for itself in energy savings.

ErP Explained 

ErP stands for Energy-Related Products and is a way of measuring an energy consuming appliance, such as a boiler’s, efficiency in converting the energy it uses into the desired product, heat for your property and its water.

ErP was introduced in 2009 by the European Union in order to increase the clarity of an appliance’s function and aid in the sharing of information from manufacturer to consumer, all the while promoting an eco-consciousness for both.

Energy Labelling

This aspect of ErP is to inform consumers with complete transparency, the energy efficiency of the product they are buying, and its subsequent likelihood of affecting their energy bills.


Appliances are rated in energy efficiency classifications from G to A (A+++ for certain types of appliance); the higher the assigned alphabetical rating, the more efficient the appliance is in terms of its energy usage.

Formerly SEDBUK (Seasonal Efficiency of Domestic Boilers) were responsible for boiler energy ratings, the ErP directive replaced them in the majority of cases for modern appliances.

Some manufacturers still attach a SEDBUK rating to their products, and operate a similar alphabetical classification system.

Naturally, the newer a gas boiler system, the more efficient it is due to engineering and design progression. 

Outdated or failing systems could be the reason for your shock when seeing your monthly energy bills

Most UK boilers are running at 80% energy efficiency with some antiquated models operating at 60% or less! These sub optimal levels of output are as avoidable as they are shocking.

Age of Boiler

Efficiency Percentage

Efficiency Rating

0+ Years

90% +


10+ Years

85% +


15+ Years

80% +


20+ Years

70% +


25+ Years

60% +


The direct correlation between boiler age and its efficiency is clear to see in the newer systems’ ErP, so it may be worth upgrading your model to an energy efficient boiler. check out our handy guide on the most energy efficient boilers.

The power of Efficiency

Efficiency is a key consideration when it comes to choosing a boiler for your home. Viessmann boilers including the Viessmann Vitodens 100-W series, are renowned for their excellent efficiency ratings. 

These boilers are designed to convert a significant amount of the fuel they consume into useful heat, therefore minimising waste.

The Viessmann Vitodens 100-W series offers several models with varying kW size outputs catering to different household sizes and heating requirements. Notable models in this series include:

These boilers feature an advanced combustion technology and modulation burners which optimise energy usage by adjusting the heat output based on demand.

This results in improved efficiency leading to reduced energy bills and a greener carbon footprint.


Sustainability in Action

Modern boilers, such as the Viessmann Vitodens collection, go beyond efficiency by embracing sustainability. 

The company prioritises the use of environmentally friendly designs that contribute to a cleaner and more sustainable future.

One key sustainability feature is the utilisation of condensing technology. Condensing boilers maximise energy efficiency by capturing heat from flue gases and recycling it back into the system. 

This process significantly reduces energy waste and carbon emissions, making these boilers an eco conscious choice.

Viessmann’s commitment to sustainability extends beyond these modern boilers, Viessmann incorporates the use of recyclable materials in their production processes. 

By choosing a Viessmann boiler, homeowners can ensure they are taking a positive step in the reduction of un-environmentally friendly commerce.

Advantages of Modern Boilers

Investing in a modern boiler brings a multitude of benefits to homeowners, these include:

Reduced Energy Consumption         

Modern boilers like the Viessmann Vitodens 100-W range are designed to minimise energy waste and reduce your heating bills.

Cost Savings

By using less energy, efficient boilers can lead to substantial cost savings over time. The initial investment in a high quality boiler is often offset by long term energy savings.

Quiet Operation

Viessmann boilers are designed to operate quietly ensuring a peaceful home environment. with advanced sound insulation, modern Viessmann boilers reduce unnecessary noise 

Enhanced Comfort

Modern boilers provide consistent and reliable heat, ensuring optimum heat around your home. They deliver precise temperature control and quick response times, creating a cosy living environment.

Environmental Friendliness

Choosing an efficient boiler means reducing your carbon footprint - by decreasing energy consumption you contribute to a more sustainable future.

Longevity and Reliability

Modern Viessmann Vitodens boilers are built to last with expertly designed mechanisms and carefully constructed components, with proper maintenance and regular servicing these boilers offer extended life spans.

Seamless Integration

Viessmann boilers are designed to seamlessly integrate to various heating systems, whether you have a traditional radiator system or underfloor heating, these efficient boiler can work with any setup.

Smart Connectivity

Viessmann offers smart connectivity options, allowing homeowners to control and monitor their boilers remotely. 

Here at iHeat we offer stress free boiler installation and fixed price online quotes in as little as 60 seconds, offering many top brand ranges, including Viessmann Vitodens.

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Frequently Asked Questions

Are Viessmann Boilers Any Good?

Viessmann boilers are renowned for their exceptional quality, reliability, and energy efficiency. With a strong reputation in the heating industry, they offer innovative features that enhance performance and user comfort. Their boilers are designed to meet the needs of a wide range of households, making them a top choice for those seeking durable and efficient heating solutions.

Which Viessmann Boiler Is the Most Reliable?

When considering reliability, Viessmann boilers consistently rank at the top, alongside other reputable brands such as Worcester Bosch and Baxi. The key to finding the most reliable boiler lies in comparing customer reviews, warranty offers, and the brand's track record for quality and service.

How Long Should a Viessmann Boiler Last?

A well-maintained Viessmann boiler should last between 15 to 20 years. This lifespan is indicative of the brand's commitment to quality and durability, ensuring that homeowners enjoy long-term, reliable heating performance. Regular maintenance is crucial to achieving this longevity.

Are Viessmann Boilers Energy Efficient?

Yes, Viessmann boilers are among the most energy-efficient on the market. Many of their models achieve A-rated efficiency levels, incorporating advanced technology like condensing boiler technology to minimize energy waste and reduce heating costs.

How Efficient Is a Viessmann Boiler?

Viessmann boilers boast high efficiency, often exceeding 90% efficiency ratings in various models. This efficiency translates into significant energy savings and reduced carbon emissions, making Viessmann a smart choice for eco-conscious homeowners.

Who Makes Viessmann Boilers?

Viessmann boilers are produced by the Viessmann Group, a renowned family-owned company based in Allendorf, Germany. With over 100 years of experience, Viessmann is a leading name in the heating, industrial, and refrigeration systems industry, known for its commitment to quality, innovation, and sustainability.

Are Viessmann Boilers Quiet?

Viessmann boilers are designed to operate quietly, making them an ideal choice for installation in or near living spaces. Their low noise output ensures a comfortable home environment without the disturbance often associated with heating systems, highlighting Viessmann's attention to user comfort and satisfaction.

Stephen Day profile photo
Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.