Viessmann Vitodens 100-W Combi Boiler with their compact dimensions, low weight and quiet operation will integrate effortlessly into any living space. The modulating ratio over the entire output range is up to 1:6. This high ratio makes these boilers particularly suitable for use in small apartments and well insulated buildings. The user benefits from fewer appliance start-ups and therefore less operating noise. Because a lower level of stress is placed upon the appliance, the service life of components is consequently extended. As is the case with all Viessmann gas condensing boilers, the Vitodens 100-W is equipped with stainless steel Inox-Radial heat exchangers. This technology brings with it an extremely high efficiency rate of 98 percent and exceptionally reliable and efficient operation during its long service life. Viessmann guarantees the Inox-Radial heat exchanger for ten years against leaks resulting from corrosion. The Vitodens 100-W wall mounted gas condensing boilers are controlled by the new, backlit LCD touchscreen, which makes it easy to use and read in dark environments.