Vaillant VU 25CS/1-7 ecoTEC exclusive IoniDetect

Product detailed description

Vaillant VU 25CS/1-7 ecoTEC exclusive IoniDetect
- wall-mounted condensing boiler with the option of connecting an external storage tank
- output: 2,8 - 27,0 kW 
- standardised gas utilisation rate: 109,5 %
- modulation: 1:10
- VR 921 module for remote management included with the boiler

Frequently asked questions

• How exactly do I choose the right output for a VAILLANT condensing boiler? The starting point is the calculated heat loss of the heated building (most reliably taken from the project documentation or an energy certificate). If you don't have a project, you can estimate roughly 60-100 W per m² of floor area for a normally insulated house built after 2000, or 100-150 W/m² for an older, non-insulated house - the exact figure varies depending on the number of floors, ceiling height, the number and quality of windows, and the building's orientation. A boiler oversized for its output switches on and off more often (so-called cycling), which shortens its lifespan and reduces efficiency; an undersized boiler, on the other hand, cannot sufficiently heat the house on frosty days.
• Why is a condensing boiler more economical than a classic one? A condensing boiler also makes use of the heat hidden in the water vapour produced when gas is burned - in a classic boiler this heat escapes unused through the flue, while in a condensing boiler it is cooled below the so-called dew point, the vapour condenses, and the released heat is returned to the heating circuit. Thanks to this, condensing boilers reach an efficiency of approximately 105-110% relative to the calorific value of the gas, compared to the usual 85-92% for classic boilers.
• What type of flue gas exhaust does this boiler need? Most modern condensing boilers are so-called turbo boilers (with a sealed combustion chamber) and require a concentric (coaxial) or separate flue gas exhaust and combustion air supply routed through the outer wall or roof - so they do not need a functional chimney. You will find the exact type and maximum length of the exhaust (depending on the 60/100 or 80/125 mm diameter) in the technical documentation for the specific model, or you can consult our customer service.
• What does the ErP energy class stated for the boiler mean? This is a mandatory efficiency label for heating appliances under the EU ErP (Ecodesign) directive, similar to the energy labels on refrigerators. Condensing boilers commonly reach class A, or even higher in combination with room control (e.g. A+ when using weather-compensated control and a room thermostat).
• Can I install and connect this boiler myself? No. Connection to the natural gas supply, the electrical network and the flue gas exhaust is, by law, exclusively the job of a person with the relevant authorisation (most often an authorised service technician of the given brand or a gas appliance inspection technician). After installation, the boiler must be commissioned by the manufacturer's authorised service, which is usually also a condition for the warranty to be valid.
• What about servicing and the warranty? Most manufacturers require a regular annual service inspection by an authorised service provider in order for the warranty to remain valid even after its standard expiry (an extended warranty with regular servicing is common especially for the brands Vaillant, Protherm, Viessmann). You will find the exact warranty terms in the warranty certificate supplied with the boiler.
• What is included in the delivery of this specific product? The exact package contents (the boiler itself, possibly a hot water tank, room control and other accessories in the case of a set) are stated in the product name and in its technical parameters higher up on this page.