BS EN 1749:2020 pdf download.Classification of gas appliances according to the method of supplying combustion air and of evacuation of the combustion products (types).
NOTE 1 The figures given in this annex have been included as examples to assist in the identification of thevarious appliance "types" and they are not to scale. However, it is important to stress;
a) that alternatives to any given example are equally valid if they fit the description of that particular appliance
type, and
b) that these figures are not intended to be used as a guide to installation of such appliances; in all matters
concerning installation, it is essential to refer to the installation rules in force in the CEN member country inwhich the appliance type is to be installed.
NOTE 2 For convenience, the figures for type B3, type C2, type Ca, type Cg. type C(1o), type C(12y, show thecommon duct system with each of the specific variations in type connhected to it. For the reasons given in NoTE 1above, this will not be regarded as accepted installation practice.
NOTE 3 In order to make sure that the sense of definitions is clear, each part of the flue and air system(appliance, chimney, part of the buildings) is shown with different marks to define if the part of the system is to beconsidered as an integral part of the appliance or as a separate chimney product [see the key below).
Where the connecting flue pipes are not shown they are not an integral part of the appliance.The key below applies to Figures A1 to A.20 and to Figures B.1 to B.12.
