EN 297:1994/A2:1996/AC:2006

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
       2.2.11 Control dampers in the air duct or combustion
              products circuit
  2.3 Burners
  2.4 Pressure test points
  2.5 Chemical composition of the condensate
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
       3.4.3 Pre-purge
  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
  3.11 Condensation in the boiler
  3.12 - Spare
  3.13 Frost protection system for boilers intended to
       be installed in a partially protected place
  3.14 Protection against the ingress of rain
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
       4.4.3 Pre-purge
       4.4.4 Operation of a permanent ignition burner
              when the fan stops during standby
  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
       4.5.9 Proof of air flow
       4.5.10 Dampers
  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
  4.9 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.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
       B.3.1 Belgium
       B.3.2 France
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
  F.1 Minimum requirements
  F.2 Minimum requirements for boilers with
      fan, without permanent or alternating
      ignition burner and without pre-purge
Annex G (informative) Table identifying conformity with
        the essential requirements of the gas appliance
        directive
Annex H (informative) Deviation A for Switzerland
Annex J (informative) Determination of the heat losses
        from the test rig of the indirect method and the
        contributions of the circulating pump of the test rig
Annex K (informative) Means of determining the ignition time
        at full rate

Annex L (informative) Example of calculation of the weighting
        factors for a boiler with several rates
  L.1 Apportioning of Qpi = 20%
  L.2 Apportioning of Qpi = 40%
  L.3 Apportioning of Qpi = 60%
  L.4 Apportioning of Qpi = 70%
  L.5 Total apportioning
Annex M (informative) Calculation of conversions of NO[x]
Annex N (informative) Schematic representation of the
        classification of type B boilers
Annex O (informative) Example calculation for testing the
        protected nature of a combustion chamber
  O.1 Description of the test
  O.2 Calculation example
Annex P (informative) Information on test conditions for
        aerodynamical properties of flue terminal
  P.1 General situation
  P.2 Specification of test assembly
  P.3 Situations with horizontal and vertical terminals
National annex NA (informative) Committees responsible
National annex NB (informative) Cross-references

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.