Pollution of the boiler depends on the environment in which it works (dust, humidity) and the quality of heating and non-potable water. Already several millimetres of soot and a poorly adjusted burner cause an increase in energy consumption. It is therefore important to have gas appliances regularly checked by a professional at least once a year, always before or after the heating period. In terms of the operational efficiency and security, all gas appliances as well as gas distribution should be checked.