Converting fuel oil into heat

Our oil condensing boilers are reliable and efficient heating and hot water solutions. They can be ideal for a wide range of properties, including the estimated four million households that are not connected to the UK’s gas network.

Converting fuel oil into heat, oil condensing boilers are highly efficient. They extract nearly all of the heat contained in the flue gases, turning this into additional heating energy and therefore minimising waste. In fact, Viessmann oil condensing boilers have an unbeaten high efficiency of 98 per cent*. So, using one of these appliances will help you to save energy and reduce your carbon footprint.

Our condensing oil boilers are also future-proofed. They are designed to accommodate a switchover from fossil oil to fuel oil mixed with bio-oil, meaning that they can be powered partially by renewables.

In addition, the boilers in this range can be combined with Viessmann solar technology, allowing you to take advantage of free energy from the sun. Viessmann system technology guarantees that these systems will fit together seamlessly and work in harmony.

*relative to the gross calorific value (Hs)

Which heating system is the best for you?

Oil condensing boiler product line-up

  • EfficiencyLabel
Vitorondens 200-T
A compact and affordable cast iron, oil condensing boiler 

The Vitorondens 200-T oil condensing boiler has an impressive price/performance ratio. Delivered in a block, with the downstream heat exchanger, thermal insulation and control unit fitted on site, it’s ideal for modernisat...

  • Designed for
  • Powered by
  • Ideal for
  • Up to
    107.3 kW
Discover the Vitorondens 200-T
Vitoradial 300-T
Efficient heating with condensing technology

Featuring a compact design and low build height that’s ideal for modernisation projects, the Vitoradial 300-T is an efficient low temperature boiler that comes with an Inox-Radial heat exchanger directly attached.

  • Larger residential
  • Ideal for
  • Up to
    545 kW
  • Available for
Discover the Vitoradial 300-T

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Design & Technology

Viessmann oil condensing boilers feature heat exchangers that cool the flue gases before they escape into the chimney. This rapid cooling causes the gases to condense and generates additional heat that is transferred into the heating system. Because of this process, condensing boilers function more efficiently than non-condensing models. This means that more of the money you spend on fuel is converted into warmth and hot water for your home. In turn, this saves you money and reduces your environmental impact.

Saving up to 35% energy with a modern oil condensing boiler

Older boilers are generally inefficient and often consume much more fuel than necessary. In the UK, many heating systems over 25 years old are still in operation. By replacing a technically obsolete heating system with a highly efficient oil condensing boiler - and using this in combination with solar technology - you could reduce your energy usage by up to 35 per cent.

Oil condensing boiler with Inox-Radial heat exchanger

All Viessmann oil condensing boilers are equipped with the stainless steel Inox-Radial heat exchanger. This highly robust technology offers an impressive efficiency of 98 per cent and is characterised by a long service life and safe and efficient operation.

Find the right oil condensing boiler for you and your heat requirements from this overview.

Efficient heating with oil condensing technology

Condensing technology not only utilises the heat generated by combustion as a measurable temperature of the hot gases (net calorific value), but also the water vapour content (gross calorific value). Condensing boilers are able to extract almost all of the heat contained in the flue gases and to convert it into heating energy.

Condensing boilers use high performance heat exchangers. These cool the flue gases before they escape through the chimney, to the extent that the water vapour contained in these gases is deliberately condensed. This releases additional heat which is transferred into the heating system.

With this technology, an oil condensing boiler achieves a standard seasonal efficiency [to DIN] of up to 98 % (relative to Hs). An oil condensing boiler is particularly energy efficient, looking after both your wallet and the environment.

Gross calorific value (Hs)

The gross calorific value (Hs) defines the amount of heat released by complete combustion including the evaporation heat latent in the water vapour of the hot gases.

Heating with oil

By using a Viessmann condensing boiler to convert fuel oil into heat, you are making an active contribution towards using resources efficiently and saving energy, thanks to the boiler's unbeatably high efficiency of 98 percent (relative to the gross calorific value (Hs)).

Our oil condensing boilers come with the future built in. They are designed to accommodate a changeover from fossil oil to fuel oil mixed with a certain percentage of bio-oil, which means that they can be run partially on renewables.

Oil condensing boilers use state-of-the-art heating technology

Oil boilers are still one of the most frequently used heating systems. No wonder, because the fuel is rich in energy and the system is considered safe. If homeowners decide to buy a Viessmann condensing boiler for oil, they also make an active contribution to conserving resources and energy. Because with an unrivalled high efficiency, the heating oil used is converted into heat by up to 98 percent.

Viessmann oil condensing boilers are already future -proofed. Because ex works they are prepared for a switch from fossil oil only to heating oil with a proportion of bio-oil and can thus also be operated with regenerative energy sources. In this way, every owner of an oil-fired heating system with oil condensing boiler makes an active contribution to climate and environmental protection. Viessmann has the right oil condensing boiler for every heating requirement.

Combining a new oil condensing boiler with solar collectors

You can further cut your costs and carbon footprint by using solar heating technology in conjunction with your oil condensing boiler.

To take advantage of the free energy provided by the sun, we recommend that every new oil fired condensing boiler is combined with solar collectors. When you operate one of these boilers in conjunction with Vitosol solar collectors to support heating, the requirements of the Renewable Energies Heat Act and the Renewable Energies Heat Act (EWärmeG) (Baden-Württemberg) are met. This means you can apply for public subsidies for your investment.

Vitoset heating oil tanks

As well as providing oil condensing boilers, we offer heating oil tanks that ensure economical, space-saving and problem-free storage of heating oil. The tanks in our Vitoset range are safe for use in heating systems in a range of properties, including family homes, apartment buildings, residential complexes or commercial buildings. Whether you’re building a new property or extending or renovating an existing one, our Vitoset tanks could be ideal.

Operating your new oil condensing boiler via the internet

With the free ViCare app, your new oil condensing boiler can be conveniently controlled online - even when you’re away from home. The only thing you need in order to experience this digital operating convenience is the Vitoconnect Internet interface, which can be set up by your heating engineer on request during the installation.

Operating your new oil condensing boiler via the Internet

With the free ViCare App, your new oil condensing boiler can then be conveniently controlled online via app - even from your holiday resort or workplace. For this digital operating convenience, only the Vitoconnect Internet interface is required, which can be set up by your heating engineer on request during the new installation.

How oil heating with condensing technology works

During the combustion of heating oil, hot flue gases are produced in addition to heat, which in older boilers are routed outside through the chimney. This is necessary for two reasons. On the one hand, some components of the flue gases are very acidic and can damage the system itself and the flue gas lines in the long term. On the other hand, the flue gases must not condense, as otherwise they become too heavy and can no longer escape from the chimney. This constructional procedure leads to the fact that the heat hidden in the exhaust gases remains unused.

Compared to older condensing boilers for oil from Viessmann, condensing boilers also use this latent "heat of condensation". This is released when the flue gases cool down and the resulting hot water vapour condenses. In this way, up to 98 percent of the energy content of the heating oil is converted into heat. Detailed descriptions of this procedure can also be found in the section Functioning of oil condensing technology.

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