Combustion gas and air-combustion gas chimney system has been designed for construction of chimneys operating at overpressure, extracting wet combustion gases from devices with a closed combustion chamber. A typical series of diameters of 60-80 mm, with silicon seals. Operating temperature 200°C, max. overpressure 200 Pa. The system has been made of 1.4404 acid resistant steel, plate thickness 0.5 mm. Pipes are plasma-arc welded, 60 mm pipe socket connections, 5-year guarantee, INIG technological approval.