Vaillant VU 25CS/1-7 ecoTEC exclusive IoniDetect + VIH Q 75 B below the boiler + sensoCOMFORT 720 + VR 940f

Product detailed description

Note: The connection between the boiler and the storage tank is not included in the set.

A wall-mounted condensing boiler for heating on natural gas (propane) with flue gas discharge through a wall, roof, or possibly a shaft or skylight.

PARAMETERS

Frequently asked questions

• How exactly do I choose the output of a VAILLANT condensing boiler? The basis is the calculated heat loss of the heated building (most reliably 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 commonly insulated house built after 2000, or 100-150 W/m² for an older, uninsulated house - the exact figure varies depending on the number of floors, ceiling height, number and quality of windows, and building orientation. A boiler oversized for the required 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 additionally makes use of the heat hidden in the water vapor produced when burning gas - in a classic boiler this vapor leaves unused through the chimney, while in a condensing boiler it is cooled below the so-called dew point, the vapor condenses, and the released heat is returned to the heating circuit. Thanks to this, condensing boilers achieve 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 discharge does this boiler need? Most modern condensing boilers are so-called turbo boilers (with a sealed combustion chamber) and require a coaxial (concentric) or separate flue gas discharge and combustion air supply routed through an exterior wall or roof - so they do not need a functional chimney. You can find the exact type and maximum length of the discharge (according to the 60/100 or 80/125 mm diameter) in the technical documentation for the specific model, or consult our customer service.
• What does the ErP energy class shown 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 achieve class A, or higher in combination with room controls (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 discharge is by law exclusively the responsibility of a person with the appropriate qualification (most often an authorized service technician of the given brand or a gas appliance inspection technician). After installation, the boiler must be commissioned by the manufacturer's authorized service, which is usually also a condition for the warranty to be valid.
• What about service and warranty? Most manufacturers require a regular annual service inspection by an authorized service provider so that the warranty remains valid even after its standard expiry (an extended warranty with regular servicing is common especially for the brands Vaillant, Protherm, and Viessmann). You can find the exact warranty conditions in the warranty card supplied with the boiler.
• What is included in the delivery of this specific product? The exact package contents (the boiler itself, possibly a domestic hot water cylinder, room controls, and other accessories in the case of a set) are stated in the product name and in its technical parameters above on this page.