This European Standard covers apparatus for measuring gas concentrations and other combustion parameters, as used in the installation and maintenance of heating appliances. Such apparatus may be used for testing the performance of appliances for different types of fuels, either by the installer, maintenance engineer or inspector.The apparatus may consist of different functional modules, which may be tested separately for complying with this standard and will be combined in different ways according to the different applications. This part of EN 50379 specifies the general requirements and is supplemented by the requirements in EN 50379 2 and/or EN 50379 3.This European Standard specifies general requirements for the construction, testing and performance of portable spot reading apparatus designed to give an assessment of specific combustion flue gas parameters, such as concentration of gaseous compounds, temperature and/or pressure, to check the combustion performance of heating appliances for domestic residential and commercial applications, using commercially available fuels.This European Standard excludes apparatus for- continuous emission, safety monitoring and control, and- use in vessels with an international load line.NOTE 1 When this apparatus is used in industrial premises national regulations may apply.NOTE 2 Apparatus may contain functional modules which are not covered by this standard e.g. measurement of smoke spot number (see EN 267:2009 A1:2011, Annex A) and/or measurement of indoor ambient air (see EN 50543).