"The three-pass Vitoplex 300 boiler with proven multi-layer convective heating surfaces ensures particularly economical, clean and reliable operation. The Vitoplex 300 multilayer convection heating surfaces consist of telescopic steel tubes pressed into each other for perfect heat transfer. The inner tube with folded linear fins creates a heating surface 2.5 times larger than that of smooth tubes.

Heat transfer occurs proportionally due to the different gaps between the pressing points, so the back of the triplex tubes transfers less heat to the boiler water, as the combustion products circulating here are no longer as hot. In this way, the surface temperature remains above the dew point, counteracts condensation and prevents corrosion. "