A double-walled chimney or a sandwich is a structure that consists of two pipes (external and internal) with different diameters. The space between these pipes is filled with a heat-insulating material of non-flammable properties, made of high-quality basalt fiber. Due to this design, the internal tube quickly heats up, which subsequently makes it possible in a short time after the start to raise the temperature in the chimney above the "dew point", thereby avoiding condensation.
The chimney system has a standard set of elements, with the help of which it is possible to compose a smoke channel for practically any level of complexity. Each element is connected to the other according to the socket scheme, they can be used within the external and internal installation, as well as the installation of separately standing chimney systems. The elements are released in a range of diameters from 80 to 300 mm.