Homeowners Professionals

Combi Boilers, Energy-Efficient & Gas Condensing

Viessmann's combi boilers & DHW heating systems are energy efficient & perfect for homes with a high demand for hot water. View the complete Vitodens range online.

A high-efficiency water heater and a central heating boiler in a single compact unit

Typically referred to simply as a ‘combi boiler’, a gas combination boiler is a single compact unit that combines a central heating boiler and  high-efficiency water heater.

Our combi boiler range is designed for  maximum energy efficiency. This means that by choosing a Viessmann combi boiler you will be saving on your energy bills and helping to protect the environment.

Our entire combi boiler range is rated energy efficiency class: A.

All of the boilers we provide are built around our long established reputation for high quality heating systems and are equipped with the latest heating technology.

How does a gas condensing combi boiler work?

Gas condensing combi boilers provide both heating and hot water on demand. In other words, these space-saving units heat water when it is required, rather than heating it and storing it for use later. This means they don’t require you to have a hot water storage cylinder or a cold water storage tank - as are found with conventional boiler systems. They are quick and easy to install because they have fewer external components than alternative heating systems.

These energy efficient combi boilers are connected to the mains water supply and are on continual standby. When a tap is turned on, they heat the water through a heat exchanger, giving you hot water when you need it regardless of the time of day or night.

Because they eliminate the need for water tanks, they can provide you with extra space in your home. This can be a particular benefit in smaller properties where square footage is limited.

Modern gas condensing combi boilers are designed to be extremely energy efficient. Unlike older non-condensing models, which can waste a considerable amount of heat in the form of hot gases that are released from the flue, condensing boilers capture some of this heat energy and use it to heat up water returning from the central heating system. This means that more of the money you spend on gas will be converted into warmth for your home.

Gas condensing combi boilers are the most popular choice of heating system in the UK and for many households, they provide the most effective and efficient heating and hot water solution. We provide a variety of models designed to accommodate different needs.

Benefits of a Viessmann combi boiler

When you choose a Viessmann gas condensing combi boiler, you can rest assured you’re getting the highest standards of performance. Our models are exceptionally reliable and they are built to last. They are also highly efficient, converting up to 98 per cent of the natural gas they use into heat. This will help you to lower your energy bills and cut your  carbon footprint.

Our gas combi boilers have also been created with smart technology in mind, allowing you to control them from wherever you happen to be.


Our range of gas condensing combi boilers also bring a range of other benefits. For example:  

Their compact size make them ideal for smaller properties.
Only one unit is needed to deliver heat to your radiators and hot water to your taps.
No requirement for a separate pump, hot water cylinder or cold water storage tank.
They are quicker to install because they have less external components than other boiler systems.
Hot water is delivered to your taps and shower at mains pressure.
There is no risk of cold water storage pipework freezing in the loft.
They have the ability to adapt to heating demand without constantly switching on/off, meaning smoother operation, less wear and tear on components and greater reliability.
Comprehensive warranty on the entire range, as standard.
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