Dangerous defects in exhaust pipes and boilers can be detected by a leak test. This test result is also reliable in the event of an accident if the results are properly documented.
The leak test works as follows: A measuring device applies a constant overpressure to the exhaust system. To keep the pressure constant, it pumps in air. The air flow required to maintain the pressure during the measurement period corresponds to the leakage rate. If this is less than or equal to the permissible leakage rate according to DIN EN 1443, the system works flawless. The pressures used for the measurement as well as the permissible leakage rate depend on the installation class of the chimney: N for exhaust systems in negative pressure operation (test pressure 40 and 20 Pa), P for operation with low positive pressure (test pressure 200 Pa), M for operation with medium positive pressure (test pressure 1500 Pa) and H for high pressure operation (test pressure 5000 Pa). The test pressure is based on the installed exhaust pipe and not on the delivery pressure of the fireplace. Thus, it is not, as is often assumed, only the exhaust systems of combined heat and power units that must be subjected to an H test. Rather, the test pressure must be set to 5000 Pa for all systems marked H, regardless of the boiler manufacturer's specifications for the delivery pressure.
The Wöhler DP 600 leak tester can be used to test all plants, including those in high-pressure operation with a test pressure of 5000 Pa. The device offers a pressure measuring range of ± 7,000 Pa.