BS EN 297:1994

Gas-fired central heating boilers. Type B$d1$d1 and B$d1$d1$dB$dS boilers fitted with atmospheric burners of nominal heat input not exceeding 70 kW (British Standard)

This European Standard specifies the requirements and test methods for the construction, safety, fitness for purpose, rational use of energy, classification and marking of gas-fired central heating boilers, hereafter referred to as 'boilers'.  This standard applies to type B11 and BB11BS boilers:  - fitted with atmospheric burners; - that use gases corresponding to the three gas families and to the pressures   stated in 4.1.4; - that have a nominal heat input not exceeding 70 kW (on net calorific value); - where the temperature of the water does not exceed 95 øC during normal   operation; - where the maximum water-side operating pressure does not exceed 6 bar.  This standard does not contain all the necessary requirements for:  boilers:  - intended to be installed in the open; - having multiple heating units with a single draught diverter; - with fan-assisted combustion; - of the condensing type; i- ntended to be connected to a common flue having mechanical extraction; - fitted with manual or automatic means of adjusting the air supply and/or   adjusting the evacuation of the combustion products; - of the combination type (central heating and domestic hot water production);  appliances:  - combining the functions of an independent space heater and a hot water   generator for central heating.  This standard only covers type testing.