Ceramic chimney pipes for chimney systems are a traditional and desirable material, mainly due to their high heat and corrosion resistance. In order to reduce CO2 emissions, ie to achieve higher fuel utilization and lower heating costs, but also to reduce CO and dust emissions, ie to increase the purity of flue gas, new boilers for the combustion of solid, liquid and gaseous fuels with higher efficiency. These boilers also use the latent heat of the flue gas and condensate forms in the chimney system. Therefore, higher demands are placed on chimney systems, for resistance to moisture, condensate, but also to reduced gas permeability, which is required for energy passive houses.