I.S. EN 303-3:1999

Foreword
1 Scope
2 Normative references
3 Definitions
  3.1 gas rates
      3.1.1 volumetric rate
      3.1.2 mass rate
  3.2 heat input
      3.2.1 nominal heat input
  3.3 outputs
      3.3.1 useful output
      3.3.2 nominal output
  3.4 useful efficiency
  3.5 nominal voltage
  3.6 boiler to be installed in the living space
  3.7 unit
4 Assembly requirements
  4.1 General principles
  4.2 Materials
  4.3 Combustion products evacuation ducts
5 Operational requirements
  5.1 General
  5.2 Heat inputs
  5.3 Safety of operation
      5.3.1 Limiting temperature of adjusting control
            and safety devices
      5.3.2 Limiting temperature of the side walls, the
            front and the top
      5.3.3 Limiting temperature of the floor and the
            test panels
      5.3.4 Operation of control and safety thermostats
      5.3.5 Carbon monoxide
  5.4 Useful efficiencies
      5.4.1 Useful efficiency at the maximum nominal heat
            input (see fig. 4)
      5.4.2 Useful efficiency at part load (see fig.4)
  5.5 Required draught and combustion products circuit
      resistance
6 Test methods
  6.1 General
      6.1.1 Conduct of the tests
      6.1.2 General test conditions
  6.2 Heat inputs
  6.3 Safety of operation
      6.3.1 Limiting temperature of adjusting, control
            and safety devices
      6.3.2 Limiting temperature of the side walls, the
            front and the top
      6.3.3 Limiting temperature of the floor and the
            test panels
      6.3.4 Checking the operation of control and safety
            thermostats
      6.3.5 Carbon monoxide
  6.4 Useful efficiencies
      6.4.1 Useful efficiency at the maximum nominal heat
            input
      6.4.2 Useful efficiency at part load
  6.5 Required draught and combustion products circuit
      resistance
7 Instructions
Annex A (informative) Diameters of combustion products
         evacuation ducts marketed in the various countries
Annex B (informative) Practical method of calibrating the
         test rig to enable determination of heat loss, D[p]
Annex C (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 D (informative) Determination of the ignition time at
         full rate
Annex E (normative) Assembly criteria
Annex F (informative) Ranges of boilers
Annex G (normative) Case of a boiler body which has already
         been tested with a liquid fuel burner in accordance
         with EN 303-1, EN 303-2 and EN 304 (see foreword
         and clause 1)
Annex ZA (informative) Clauses of this European Standard
         addressing essential requirements or other provisions
         of EU Directives

Defines requirements and test methods for the construction, the safety and rational energy of an assembly made up of a boiler body complying with EN 303-1, a forced draught gas burner of EN 676, using combustible gases, referred to as a "boiler".