Testing commercially available gas-fired condensing appliances equipped with a combustion control system

E.ON Ruhrgas has tested the four commercially available condensing appliances equipped with a combustion control system at its test facility under near-field conditions to assess their operational safety and combustion hygiene when operated with gases in a Wobbe range of 11.5 kWh/m³ to 16.1 kWh/m³ and compare them with conventional condensing appliances. The test results show that the combustion control systems are extremely effective and reliable for all gases even if there are problems on the air supply or flue gas discharge side. All four appliances managed to keep the load adjusted for operation with the G20 reference gas constant within a range of a few percentage points under all test conditions. Likewise, the measured air ratios only varied insignificantly by no more than 0.05 compared with the G20 reference gas. This resulted in a very satisfactory, consistent combustion hygiene with low emission levels. The control system allows an optimal adjustment of the combustion process because the nominal air factor can be raised slightly so that NOx emissions are reduced further. These positive test results were confirmed by field tests conducted by GWI. The reliable and hygienic combustion conditions made possible by the control system offer many advantages for end users including the fact that the CO-emissions of the appliance have to be checked by the chimney sweep only every five years. Moreover, there is no need for any adjustments after installation, which makes things easier for the installation company. This way, the local utilities will be better prepared for possible future gas quality fluctuations.