Condensing boilers

Highly efficient heat generation

Modern condensing appliances are designed to use virtually the entire energy content of the fuel to transform it into heat. In contrast to previous generations of these appliances, condensing boilers reuse the heat energy of water vapour produced in the combustion process which ‘condenses’ back into liquid form, and is ultimately reused to pre-heat the cold water entering the boiler. This makes the condensing technology highly convenient, resource- and cost-efficient for heat generation.

Condensing boilers cover almost all output ranges. Wall-mounted units deliver up to 100 kW. With boilers in a cascade system (several appliances connected to each other), the output can be increased to several hundred kilowatts. Floor-standing units can supply nominal outputs of more than 10,000 kW.

Condensing boilers are often the first choice both for new installations and for refurbishment of existing central heating systems across Europe.

Heating and domestic hot water

A combination boiler (or 'combi' boiler) is called in this way because it heats water for the central heating system and for the domestic hot water taps on demand (instantaneous hot water). A 'System' or ‘Open Vent' boiler provides heated water for the central heating system and is connected to a hot water cylinder (storage tank) to provide hot water to the taps. The choice between these two options depends on various factors such as space, mains water pressure, number of bathrooms.

Perfected technology that works well with renewables

For more than twenty years, the condensing technology has been constantly advancing: increased comfort and energy efficiency, reduced emissions and noise levels, improved design and reduced size to fit any building setting. Moreover, this highly efficient technology can also be easily teamed with renewable energy sources such as a solar thermal system. Finally, condensing technology can be applied to use green fuels, such as hydrogen or sustainably sourced biomethane.

To guarantee high efficiency, it is essential that the condensing gas boiler is installed, serviced and repaired by qualified personnel.


  • Increased energy efficiency and reduced emissions
  • Easily combined with renewable energies
  • Suitable for modernisation in existing as well as new buildings
  • Easily installed and maintained
  • Extremely reliable and future-oriented thanks to connection to existing grids