Comparison between European chimney test results and actual installations

European standards regulate the certification procedure for determining chimney class temperature and the distance at which to install chimneys from combustible materials. These standards prescribe the heat stress test and the thermal shock test. The high number of roof fires due to the presence of a chimney that have recently occurred in European countries seems to be due to a weak certification procedure. In this article, experimental tests and numerical simulations have been performed to highlight the major differences between real and test conditions to identify critical aspects of the current certification procedure. The influence of the position of the chimney in the test structure, the thermocouples’ positioning and the thermal shock test initial condition have been investigated. It has been shown that flammable materials’ temperatures measured in the certification procedure can be lower than those in real installations, and this is mainly due to the fact that exhaust gas temperature in the certification procedure of chimneys can be even 350°C lower than in real installations. Then, real installations represent a more severe condition.