I.S. EN 297:1994

Foreword
1 General
  1.1 Field of application
  1.2 Normative references
  1.3 Definitions
       1.3.1 Reference conditions
       1.3.2 Combustible gases
       1.3.3 Constituent parts of the boiler
       1.3.4 Operation of the boiler
  1.4 Classification
       1.4.1 Classification of gases
       1.4.2 Classification of boilers
2 Constructional requirements
  2.1 General
       2.1.1 Conversion to different gases
       2.1.2 Materials and methods of construction
       2.1.3 Design
       2.1.4 Use and servicing
       2.1.5 Connections to the gas and water pipes
       2.1.6 Soundness
       2.1.7 Supply of combustion air and evacuation of the
              combustion products
       2.1.8 Checking the state of operation
       2.1.9 Drainage
       2.1.10 Electrical equipment
       2.1.11 Operational safety in the event of failure of
              the auxiliary energy
  2.2 Requirements for adjusting, control and safety
       devices
       2.2.1 General
       2.2.2 Adjuster and range-rating device
       2.2.3 Gas circuit
       2.2.4 Gas governor
       2.2.5 Ignition devices
       2.2.6 Flame supervision devices
       2.2.7 Thermostats and water temperature limiting
              devices
       2.2.8 Remote control
       2.2.9 Expansion vessel and pressure gauge
       2.2.10 Combustion products discharge safety device
  2.3 Burners
  2.4 Pressure test points
3 Operational requirements
  3.1 General
  3.2 Soundness
       3.2.1 Soundness of the gas circuit
       3.2.2 Soundness of the combustion circuit
       3.2.3 Soundness of the water circuit
  3.3 Nominal, maximum and minimum heat inputs and
       nominal output
       3.3.1 General
       3.3.2 Nominal heat input
       3.3.3 Maximum and minimum heat input
       3.3.4 Minimum heat input for ignition
       3.3.5 Nominal output
  3.4 Safety of operation
       3.4.1 Limiting temperatures
       3.4.2 Ignition - Cross lighting - Flame stability
  3.5 Adjusting, control and safety devices
       3.5.1 General
       3.5.2 Control devices
       3.5.3 Automatic valves
       3.5.4 Ignition devices
       3.5.5 Flame supervision devices
       3.5.6 Gas governor
       3.5.7 Thermostats and water temperature limiting
              devices
       3.5.8 Combustion products discharge safety device
  3.6 Combustion
       3.6.1 Carbon monoxide
       3.6.2 Other pollutants
  3.7 Useful efficiencies
       3.7.1 Useful efficiencies at the nominal heat input
       3.7.2 Useful efficiencies at part load
  3.8 Condensation in the flue
  3.9 Resistance of the materials to pressure
       3.9.1 General
       3.9.2 Boilers of pressure class 1
       3.9.3 Boilers of pressure class 2
       3.9.4 Boilers of pressure class 3
  3.10 Hydraulic resistance
4 Test methods
  4.1 General
       4.1.1 Characteristics of the reference and limit gases
       4.1.2 Requirements for the preparation of test gases
       4.1.3 Carrying out the tests
       4.1.4 Test pressures
       4.1.5 Conduct of the tests
       4.1.6 General test conditions
       4.1.7 Summary of the test conditions
  4.2 Soundness
       4.2.1 Soundness of the gas circuit
       4.2.2 Soundness of the combustion circuit
       4.2.3 Soundness of the water circuit
  4.3 Nominal, maximum and minimum heat inputs and
       nominal output
       4.3.1 General
       4.3.2 Nominal heat input
       4.3.3 Maximum and minimum heat input
       4.3.4 Minimum heat input for ignition
       4.3.5 Nominal output
  4.4 Safety of operation
       4.4.1 Limiting temperatures
       4.4.2 Ignition - Cross lighting - Flame stability
  4.5 Adjusting, control and safety devices
       4.5.1 General
       4.5.2 Control devices
       4.5.3 Automatic valves
       4.5.4 Ignition devices
       4.5.5 Flame supervision devices
       4.5.6 Gas governor
       4.5.7 Thermostats and water temperature limiting
              devices
       4.5.8 Combustion products discharge safety device
  4.6 Combustion
       4.6.1 Carbon monoxide
       4.6.2 Other pollutants
  4.7 Useful efficiencies
       4.7.1 Useful efficiency at the nominal heat input
       4.7.2 Useful efficiency at part load
  4.8 Non-condensation in the flue
       4.8.1 Exceeding the dew point temperature
       4.8.2 Determination of flue losses
       4.8.3 Maximum useful efficiency
       4.8.4 Minimum temperature of the combustion products
  4.9 Resistance of the materials to pressure
       4.9.1 General
       4.9.2 Boilers of pressure class 1
       4.9.3 Boilers of pressure class 2
       4.9.4 Boilers of pressure class 3
  4.10 Hydraulic resistance
5 Marking and instructions
  5.1 Marking of the boiler
       5.1.1 Data plate
       5.1.2 Supplementary marking
       5.1.3 Warnings
  5.2 Instructions
       5.2.1 Technical instructions for the installer
       5.2.2 Use and maintenance instructions for the user
       5.2.3 Conversion instructions
       5.2.4 Packaging
       5.2.5 Presentation
Annex A (informative) National situations
  A.1 Categories marketed in the various countries
       A.1.1 Simple categories marketed
       A.1.2 Double categories marketed
  A.2 Boiler supply pressures
  A.3 Flue connections in the various countries
  A.4 Gas connections conditions in common use in the
       various countries
Annex B (informative) Particular national conditions
  B.1 Gases distributed locally
  B.2 Special categories marketed nationally or locally
  B.3 Particular conditions
Annex C (informative) Practical method of calibrating
        the test rig to enable the heat loss Dp to be
        determined
Annex D (informative) Main symbols and abbreviations used
Annex E (informative) Summary of the test conditions
  E.1 First family
  E.2 Second family
  E.3 Third family
Annex F (informative) Composition of the gas circuit
Annex G (informative) Table identifying conformity with
        the essential requirements of the gas appliance
        directive
Annex H (informative) Deviation A for Switzerland