CLAY ELEMENTS: elements in clay concrete blocks, compliant with Standard UNI EN 12446. These elements, installed in “chimney configuration” should be considered containers for flues and not actual flues themselves. Furthermore, following specific laboratory tests executed in compliance with the specific regulations in force, it is possible to state that by following the manufacturer’s instructions (see the specific Use, Maintenance and Installation Manual) it is possible to create EN 1443. . . . . G0 designated composite chimney systems, i.e.: ZERO distance from adjacent combustible material.