I.S. EN 656:2000

1 Scope
2 Normative references
3 Definitions
      3.1 Combustible gases
      3.2 Constituent parts of the boiler
      3.3 Operation of the boiler
      3.4 Country of destination
4 Classification of boilers
      4.1 Gases and categories
      4.2 Classification according to the mode of
             evacuation of the combustion products
             4.2.1 General
             4.2.2 Type B
      4.3 Type of technologies
             4.3.1 gas condensing boiler
             4.3.2 low-temperature boiler
             4.3.3 standard boiler
5 Constructional requirements
      5.1 General
      5.2 Conversion to different gases
      5.3 Materials and method of construction
             5.3.1 General
             5.3.2 Materials and thicknesses of walls or
                      tubes under water pressure
             5.3.3 Thermal insulation
      5.4 Design
             5.4.1 General
             5.4.2 Modular boilers
      5.5 Use and servicing products
      5.6 Connections to the gas and water pipes
             5.6.1 General
             5.6.2 Connections to the gas pipe
             5.6.3 Connections to the central heating
                      circuit
      5.7 Soundness
             5.7.1 Soundness of the gas circuit
             5.7.2 Soundness of the combustion circuit
      5.8 Supply of combustion air and the evacuation of
             the combustion products
             5.8.1 Control dampers in the air or
                      combustion products circuit
             5.8.2 Fan
             5.8.3 Air proving
             5.8.4 Gas/air ratio controls
             5.8.5 Removal of condensate for low temperature
                      boilers
      5.9 Checking the state of operation
      5.10 Drainage
      5.11 Electrical equipment
      5.12 Operational safety in the event of failure of
             the auxiliary energy
      5.13 Adjusting, control and safety devices
             5.13.1 General
             5.13.2 Adjusters and range rating devices
             5.13.3 Gas circuit
             5.13.4 Gas governor
             5.13.5 Ignition devices
             5.13.6 Flame supervision systems
             5.13.7 Thermostats and water temperature
                      limiting devices
             5.13.8 Device for monitoring the evacuation
                      of combustion products
      5.14 Burners
      5.15 Pressure test points
      5.16 Chemical composition of the condensate for
             low-temperature boilers
6 Operational requirements
      6.1 General
      6.2 Soundness
             6.2.1 Soundness of the gas circuit
             6.2.2 Soundness of the combustion circuit
                      and correct evacuation of the
                      combustion products
             6.2.3 Soundness of the water circuit
      6.3 Nominal, maximum and minimum heat inputs, and
             nominal output
             6.3.1 Nominal heat input or maximum and
                      minimum heat inputs
             6.3.2 Adjustment of the heat input by the
                      downstream pressure
             6.3.3 Minimum ignition rate
             6.3.4 Nominal output
             6.3.5 Gas governor
      6.4 Safety of operation
             6.4.1 Limiting temperatures
             6.4.2 Ignition - Cross-lighting - Flame
                      stability
             6.4.3 Pre-purge
      6.5 Adjusting, control and safety devices
             6.5.1 General
             6.5.2 Ignition devices
             6.5.3 Flame supervision devices
             6.5.4 Ignition burner and ignition rates
             6.5.5 Air proving
             6.5.6 Gas pressure switches
             6.5.7 Control thermostat and safety
                      temperature limiter
             6.5.8 Device for monitoring the evacuation
                      of combustion products
             6.5.9 Condensate discharge blockage
      6.6 Combustion
             6.6.1 Carbon monoxide
             6.6.2 Other pollutants
      6.7 Useful efficiencies
             6.7.1 Useful efficiency at the nominal heat
                      input
             6.7.2 Useful efficiency at part load
      6.8 Criteria for condensation in the flue for standard
             boilers
      6.9 Resistance of the materials to pressure
             6.9.1 General
             6.9.2 Boilers of sheet steel or non-ferrous
                      metals
             6.9.3 Boilers of cast iron and cast materials
      6.10 Hydraulic resistance
      6.11 Combustion air and flue dampers
      6.12 Condensation in a standard boiler
7 Test methods
      7.1 General
             7.1.1 Characteristics of the reference and
                      limit gases
             7.1.2 General test conditions
      7.2 Soundness
             7.2.1 Soundness of the gas circuit
             7.2.2 Soundness of the combustion circuit
                      and correct evacuation of the
                      combustion products
             7.2.3 Soundness of the water circuit
      7.3 Nominal, maximum and minimum heat inputs and
             nominal output
      7.4 Safety of operation
      7.5 Adjusting, control and safety devices
      7.6 Combustion
      7.7 Useful efficiencies
      7.8 Criteria for condensation in the flue
      7.9 Resistance of materials to pressure
      7.10 Hydraulic resistance
      7.11 Combustion air and flue dampers
      7.12 Condensation in a standard boiler
8 Marking and instructions
      8.1 Marking of the boiler
             8.1.1 General
             8.1.2 Data plate
             8.1.3 Supplementary marking
             8.1.4 Packaging
             8.1.5 Warnings on the boiler and on the
                      packaging
             8.1.6 Other information
      8.2 Instructions
             8.2.1 Technical instructions for the
                      installer
             8.2.2 Use and maintenance instructions for
                      the user
             8.2.3 Conversion instructions
             8.2.3 Presentation
Annex A (informative) National situations
      A.1 - Categories marked in the various countries
      A.2 - Special categories marketed nationally or locally
      A.3 - Gas groups distributed locally
      A.4 - Boiler supply pressures
      A.5 - Gas connections in common use in the various
            countries
Annex B (normative) Special national conditions
Annex C (informative) A-deviations
Annex D (informative) Practical method of calibrating the
                      test rig to enable the heat loss Dp
                      to be determined
Annex E (informative) Main symbols and abbreviations used
Annex F (informative) Compilation of test conditions
Annex G (informative) Valving
      G.1 - General
      G.2 - Boilers with permanent ignition burner or
            alternating ignition burner or leakage control
            device or with pre-purge
            G.2.1 - Heat inputs up to 150 kW
            G.2.2 - Heat inputs up to 300 kW
      G.3 - Boilers without permanent ignition burner or
            alternating ignition burner, without leakage
            control device and without prepurge
            G.3.1 - Heat inputs up to 150 kW
            G.3.2 - Heat inputs up to 300 kW
Annex H (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 J (informative) Means of determining the ignition time
                      at full rate
Annex K (informative) Example of calculation of the weighting
                      factors for a boiler with several rates
      K.1 - Apportioning of Qpi = 20%
      K.2 - Apportioning of Qpi = 40%
      K.3 - Apportioning of Qpi = 60%
      K.4 - Apportioning of Qpi = 70%
      K.5 - Total apportioning
Annex L (informative) Calculation of conversions of NOx
Annex ZA (informative) Clauses of this European standard
                       addressing requirements or provisions
                       of EU Directives

Gives the requirements and test methods concerning, in particular the construction, safety, fitness for purpose, and rational use of energy, as well as the classification and marking of gas-fired central heating boilers that are fitted with atmospheric burners fan assisted atmospheric burners or fully premixed burners.