October 2012

Translation by DIN-Sprachendienst.

English price group 27 No part of this translation may be reproduced without prior permission of

DIN Deutsches Institut für Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,

has the exclusive right of sale for German Standards (DIN-Normen).

ICS 01.040.91; 91.140.10

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1919800

www.din.de

DIN EN 303-5 D

Heating boilers –

Part 5: Heating boilers for solid fuels, manually and automatically

stoked, nominal heat output of up to 500 kW –

Terminology, requirements, testing and marking;

English version EN 303-5:2012,

English translation of DIN EN 303-5:2012-10

Heizkessel –

Teil 5: Heizkessel für feste Brennstoffe, manuell und automatisch beschickte Feuerungen,

Nennwärmeleistung bis 500 kW –

Begriffe, Anforderungen, Prüfungen und Kennzeichnung;

Englische Fassung EN 303-5:2012,

Englische Übersetzung von DIN EN 303-5:2012-10

Chaudières de chauffage –

Partie 5: Chaudières spéciales pour combustibles solides, à chargement manuel et

automatique, puissance utile inférieure ou égale à 500 kW –

Définitions, exigences, essais et marquage;

Version anglaise EN 303-5:2012,

Traduction anglaise de DIN EN 303-5:2012-10

©

Supersedes

DIN EN 303-5:1999-06

www.beuth.de

In case of doubt, the German-language original shall be considered authoritative.

Document comprises 83 pages

10.12

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DIN EN 303-5:2012-10

2

A comma is used as the decimal marker.

National foreword

This standard has been prepared by Technical Committee CEN/TC 57 “Central heating boilers” (Secretariat: 

DIN, Germany).

The responsible German body involved in its preparation was the Normenausschuss Heiz- und Raumlufttechnik (Heating and Ventilation Technology Standards Committee), Working Committee NA 041-01-62 AA

Zentralheizungskessel (SpA CEN/TC 57).

As regards emission limits, Germany had requested that an A-deviation be applied for Germany because 

emission limits are regulated in Chapter 2, paragraphs 4 and 5, and Annex 2 of the German Immission Control 

Ordinance “Erste Verordnung zur Durchführung des Bundes-Immissionsschutzgesetzes (Verordnung über 

kleine und mittlere Feuerungsanlagen - 1. BImSchV)”. This A-deviation is given in Annex C.

Other countries had also requested an A-deviation, namely Austria, Croatia, Denmark, Switzerland, the United 

Kingdom and Italy. These A-deviations are also given in Annex C.

Amendments

This standard differs from DIN EN 303-5:1999-06 as follows:

a) the scope has been extended to a nominal heat output of the heating boilers for ≤ 500 kW;

b) usable fuel to non-wood biomass and further solid fuels have been extended;

c) requirements for materials, weld joints and wall thicknesses have been revised;

d) risk analysis has been implemented;

e) general and electrical safety requirements have been revised;

f) emission class 1 and 2 have been deleted and new emission class 4 and 5 have been added;

g) tests have been revised and new tests for safety requirements have been added;

h) annexes have been re-structured;

i) consideration has been given to the essential requirements of the Machinery Directive 2006/42/EC.

Previous editions

DIN 4701: 1929, 1944-08 

DIN 4702: 1944-02 

DIN 4702-1: 1967-01, 1979-12, 1990-03 

DIN 4702-5: 1979-12 

DIN EN 303-5: 1999-06

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EUROPEAN STANDARD 

NORME EUROPÉENNE 

EUROPÄISCHE NORM

 EN 303-5 

 

 June 2012 

ICS 01.040.91; 91.140.10 Supersedes EN 303-5:1999

English Version 

 Heating boilers - Part 5: Heating boilers for solid fuels, manually 

and automatically stoked, nominal heat output of up to 500 kW -

Terminology, requirements, testing and marking 

Chaudières de chauffage - Partie 5: Chaudières spéciales 

pour combustibles solides, à chargement manuel et 

automatique, puissance utile inférieure ou égale à 500 kW -

Définitions, exigences, essais et marquage 

 Heizkessel - Teil 5: Heizkessel für feste Brennstoffe, 

manuell und automatisch beschickte Feuerungen, NennPrüfungen und Kennzeichnung 

This European Standard was approved by CEN on 10 May 2012. 

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European 

Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national 

standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. 

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation 

under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same 

status as the official versions. 

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, 

Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. 

EUROPEAN COMMITTEE FOR STANDARDIZATION 

C O M I T É E U R O P É E N D E N O R M A LI S A T I O N 

EUROPÄISCHES KOMITEE FÜR NORMUNG 

Management Centre: Avenue Marnix 17, B-1000 Brussels 

© 2012 CEN All rights of exploitation in any form and by any means reserved 

worldwide for CEN national Members. 

Ref. No. EN 303-5:2012: E

wärmeleistung bis 500 kW - Begriffe, Anforderungen, 

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EN 303-5:2012 (E) 

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Contents Page

Foreword ..............................................................................................................................................................5

Introduction .........................................................................................................................................................7

1 Scope ......................................................................................................................................................8

1.1 General ....................................................................................................................................................8

1.2 Fuels ........................................................................................................................................................8

1.2.1 Biogenic fuels ........................................................................................................................................9

1.2.2 Fossil fuels .............................................................................................................................................9

1.2.3 Other solid fuels.....................................................................................................................................9

2 Normative references ............................................................................................................................9

3 Terms and definitions ........................................................................................................................ 12

4 Requirements ...................................................................................................................................... 17

4.1 General requirements ......................................................................................................................... 17

4.2 Construction requirements ................................................................................................................ 18

4.2.1 Production documentation ................................................................................................................ 18

4.2.2 Heating boilers made of steel and non-ferrous materials .............................................................. 19

4.2.3 Boilers made of cast materials .......................................................................................................... 24

4.2.4 Design requirements .......................................................................................................................... 25

4.3 Safety requirements ........................................................................................................................... 28

4.3.1 General ................................................................................................................................................. 28

4.3.2 Manual stoking .................................................................................................................................... 28

4.3.3 Safety against back burning for automatic stoked boilers ............................................................ 28

4.3.4 Safety against fuel overload of the boiler or interruption in fuel supply ...................................... 32

4.3.5 Safety against lack of air supply or insufficient combustion ........................................................ 32

4.3.6 Surface temperatures ......................................................................................................................... 32

4.3.7 Leakage of the combustion system .................................................................................................. 32

4.3.8 Temperature control and limiting devices ....................................................................................... 33

4.3.9 Heating boiler accessories ................................................................................................................ 34

4.4 Performance requirements ................................................................................................................ 35

4.4.1 General ................................................................................................................................................. 35

4.4.2 Boiler efficiency .................................................................................................................................. 35

4.4.3 Flue gas temperature ......................................................................................................................... 36

4.4.4 Draught ................................................................................................................................................ 36

4.4.5 Combustion period ............................................................................................................................. 36

4.4.6 Minimum heat output ......................................................................................................................... 36

4.4.7 Emission limits .................................................................................................................................... 37

5 Test ....................................................................................................................................................... 38

5.1 Test conditions ................................................................................................................................... 38

5.1.1 General ................................................................................................................................................. 38

5.1.2 Choice of boiler and fittings to be tested ......................................................................................... 39

5.1.3 Condition of the boiler ....................................................................................................................... 39

5.1.4 Type test .............................................................................................................................................. 39

5.2 Measuring instruments and methods ............................................................................................... 39

5.3 Test fuel ............................................................................................................................................... 40

5.4 Pressure test for boilers of sheet or sheet metal of non-ferrous metal ........................................ 42

5.4.1 Tests to be carried out before production ....................................................................................... 42

5.4.2 Test during production ...................................................................................................................... 42

5.5 Pressure test for boilers of cast iron or non-ferrous metals ......................................................... 42

5.5.1 Test to be carried out before production ......................................................................................... 42

5.5.2 Test during production ...................................................................................................................... 43

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EN 303-5:2012 (E) 

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5.6 Test for gas side soundness .............................................................................................................. 44

5.7 Conducting the boiler performance test ........................................................................................... 44

5.7.1 General ................................................................................................................................................. 44

5.7.2 Setting up the test rig .......................................................................................................................... 45

5.7.3 Measured quantities ............................................................................................................................ 45

5.7.4 Test method and test duration ........................................................................................................... 46

5.8 Determination of the heat output and the efficiency of the boiler.................................................. 47

5.8.1 Method for the measurement of the heat output ............................................................................. 47

5.8.2 Determining the nominal heat output ................................................................................................ 47

5.8.3 Determining the minimum heat output ............................................................................................. 47

5.8.4 Determination of the boiler efficiency (direct method) .................................................................... 48

5.8.5 Electrical consumption ....................................................................................................................... 48

5.9 Determination of the emission values ............................................................................................... 48

5.9.1 Heating boiler with manual stoking ................................................................................................... 48

5.9.2 Heating boiler with automatic stoking .............................................................................................. 48

5.9.3 Determination of the emissions at minimum heat output ............................................................... 48

5.10 Calculation ........................................................................................................................................... 49

5.10.1 Boiler heat output ................................................................................................................................ 49

5.10.2 The heat input ...................................................................................................................................... 49

5.10.3 Boiler efficiency ................................................................................................................................... 49

5.10.4 Emissions ............................................................................................................................................. 49

5.11 Determination of the waterside resistance ....................................................................................... 50

5.12 Surface temperature ............................................................................................................................ 50

5.13 Function check of the temperature controller and safety temperature limiter at the boiler ...... 50

5.14 Function test for the rapidly disconnect able firing system ........................................................... 51

5.15 Function test on the device for dissipating excess heat (partly or non disconnectable 

firing system) ....................................................................................................................................... 51

5.16 Check of the safety and risk assessment ......................................................................................... 51

5.16.1 General ................................................................................................................................................. 51

5.16.2 Safety test of consequences of fuel overload and effect of a blockage of the fuel supply ......... 53

5.16.3 Loss of combustion air supply .......................................................................................................... 53

5.16.4 Resistance to thermal conductance .................................................................................................. 53

5.16.5 Additional tests for alternative verification of the safety against back burning ........................... 53

6 Test report and other documents ...................................................................................................... 54

7 Marking ................................................................................................................................................. 55

7.1 General ................................................................................................................................................. 55

7.2 Information on the boiler plate ........................................................................................................... 55

7.3 Boiler plate requirements ................................................................................................................... 55

8 Technical documentation, supplied with boiler ............................................................................... 55

8.1 General ................................................................................................................................................. 55

8.2 Technical information and installation instructions ........................................................................ 55

8.3 Operating instructions ........................................................................................................................ 57

Annex A (informative) Manual measurement of particles in the gas flow, gravimetric 

determination of particle load with filter systems ........................................................................... 58

Annex B (normative) Design criteria for solutions to prevent back burning ............................................. 61

Annex C (informative) A-deviations ................................................................................................................ 66

C.1 General ................................................................................................................................................. 66

C.2 Deviations from Austria: ..................................................................................................................... 66

C.2.1 General ................................................................................................................................................. 66

C.2.2 Boiler efficiency for nominal heat output and minimum heat output ............................................ 66

C.2.3 Emission limits .................................................................................................................................... 67

C.3 Deviations from CROATIA .................................................................................................................. 68

C.4 Deviations from DENMARK ................................................................................................................ 69

C.4.1 Subclause 4.4.2 Boiler Efficiency ...................................................................................................... 69

C.4.2 Subclause 4.4.7 Emission Limits ....................................................................................................... 69

C.4.3 Subclause 5.1 Test Base..................................................................................................................... 70

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C.5 Deviations from Germany .................................................................................................................. 70

C.5.1 Clause 4.4.7 Emission limits .............................................................................................................. 70

C.5.2 Clause 5.9 ............................................................................................................................................ 72

C.6 Deviations from Switzerland .............................................................................................................. 72

C.7 Deviations from United Kingdom ...................................................................................................... 73

C.8 Deviations for Italy .............................................................................................................................. 77

Annex ZA (informative) Relationship between this European Standard and the Essential 

Requirements of EU Directive 2006/42/EC Machinery Directive .................................................... 79

Bibliography ..................................................................................................................................................... 81

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EN 303-5:2012 (E) 

5 

Foreword 

This document (EN 303-5:2012) has been prepared by Technical Committee /TC 57 “Heating boilers”, the 

secretariat of which is held by DIN. 

This European Standard shall be given the status of a national standard, either by publication of an identical 

text or by endorsement, at the latest by December 2012, and conflicting national standards shall be withdrawn 

at the latest by December 2012. 

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent 

rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. 

This document supersedes EN 303-5:1999. 

This document has been prepared under a mandate given to CEN by the European Commission and the 

European Free Trade Association, and supports essential requirements of EU Directive(s). 

For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document. 

In comparison with EN 303-5:1999, the following technical changes were made: 

a) the scope was extended to a nominal heat output of the heating boilers for ≤ 500 kW; 

b) usable fuel to non-wood biomass and further solid fuels were extended; 

c) requirements for materials, weld joints and wall thicknesses were revised; 

d) risk analysis was implemented; 

e) general and electrical safety requirements were revised; 

f) emission class 1 and 2 were deleted and new emission class 4 and 5 were added; 

g) tests were revised and new tests for safety requirements were added; 

h) Annexes were re-structured; 

i) Consideration was given to the essential requirements of the Machinery Directive 2006/42/EC. 

The following structure is intended for the European Standards for heating boilers: 

 EN 303-1, Heating boilers ― Part 1: Heating boilers with forced draught burners ― Terminology, general 

requirements, testing and marking

 EN 303-2, Heating boilers ― Part 2: Heating boilers with forced draught burners ― Special requirements 

for boilers with atomizing oil burners

 EN 303-3, Heating boilers ― Part 3: Gas-fired central heating boilers ― Assembly comprising a boiler 

body and a forced draught burner

 EN 303-4, Heating boilers ― Part 4: Heating boilers with forced draught burners ― Special requirements 

for boilers with forced draught oil burners with outputs up to 70 kW and a maximum operating pressure of 

3 bar ― Terminology, special requirements, testing and marking

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EN 303-5:2012 (E) 

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 EN 303-5, Heating boilers ― Part 5: Heating boilers for solid fuels, manually and automatically stoked, 

nominal heat output of up to 500 kW ― Terminology, requirements, testing and marking

 EN 303-6, Heating boilers ― Part 6: Heating boilers with forced draught burners ― Specific requirements 

for the domestic hot water operation of combination boilers with atomizing oil burners of nominal heat 

input not exceeding 70 kW

 EN 303-7, Heating boilers ― Part 7: Gas-fired central heating boilers equipped with a forced draught 

burner of nominal heat output not exceeding 1 000 kW

 EN 304, Heating boilers ― Test code for heating boilers for atomizing oil burners.

According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following 

countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech 

Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, 

Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, 

Sweden, Switzerland, Turkey and the United Kingdom. 

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EN 303-5:2012 (E) 

7 

Introduction 

This document is a type C standard as stated in EN ISO 12100. 

The machinery concerned, and the extent to which hazards, hazardous situations and hazardous events are 

covered, are indicated in the scope of this document. 

This standard deals with boilers which are within the Scope Machinery Directive and boilers that are outside of 

the Scope Machinery Directive. 

When provisions of this type C standard are different from those which are stated in type A or B standards, the 

provisions of this type C standard take precedence over the provisions of the other standards, for machines 

that have been designed and built according to the provisions of this type C standard. 

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1 Scope 

1.1 General 

This European Standard applies to heating boilers including safety devices up to a nominal heat output of 

500 kW which are designed for the burning of solid fuels only and are operated according to the instructions of 

the boiler manufacturer. 

This European Standard deals with significant hazards, hazardous situations and events relevant to heating 

boilers used as intended and under the conditions foreseen by the manufacturer (see Clause 4). 

The boilers may operate under natural draught or forced draught. The stoking may work manually or 

automatically. 

NOTE This European Standard deals with boilers which are both within and outside of the scope of the Machinery 

Directive 2006/42/EC. 

This European Standard contains requirements and test methods for safety, combustion quality, operating 

characteristics, marking and maintenance of heating boilers. It also covers all external equipment that 

influences the safety systems (e.g. back burning safety device, integral fuel hopper). 

This European Standard covers only boilers that include burners as a unit. The standard applies to the 

combination of a boiler body with a solid fuel burner according to EN 15270 as a unit only when the whole unit 

is tested in accordance with this European Standard. 

Heating boilers in accordance with this European Standard are designed for central heating installations 

where the heat carrier is water and the maximum allowable temperature is 110 °C, and which can operate at a 

maximum allowable operating pressure of 6 bars. For heating boilers with a built-in or attached water heater 

(storage or continuous flow heater), this European Standard only applies to those parts of the water heater 

which are necessarily subject to the operating conditions of the heating boiler (heating part). 

This European Standard does not apply to: 

 heating boilers and other heating appliances which are also designed for the direct heating of the place of 

installation; 

 cooking appliances; 

 the design and construction of external fuel storage and transportation devices prior to the safety devices 

of the boiler; 

 room sealed applications; 

 condensing boilers. 

This European Standard specifies the necessary terminology for solid fuel heating boilers, the control and 

safety related requirements, the design requirements, the technical heating requirements (taking into account 

the environmental requirements) and testing, as well as the marking requirements. 

This European Standard is not applicable to heating boilers which are tested before the date of its publication 

as an EN (European Standard). 

1.2 Fuels 

These boilers may burn either fossil fuels, biogenic fuels or other fuels such as peat, as specified for their use 

by the boiler manufacturer, in accordance with the requirements of this European Standard. 

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EN 303-5:2012 (E) 

9 

Solid fuels included in this European Standard are categorised as follows. 

1.2.1 Biogenic fuels 

Biomass in a natural state, in the form of: 

 A log wood with moisture content w ≤ 25 %, according to EN 14961-5; 

 B1 chipped wood (wood chipped by machine, usually up to a maximum length of 15 cm) with moisture 

content from w 15 % to w 35 %, according to EN 14961-4; 

 B2 chipped wood as under B1, except with moisture content w > 35 %; 

 C1 compressed wood (e.g. pellets without additives, made of wood and/or bark particles; natural binding 

agents such as molasses, vegetable paraffins and starch are permitted), pellets according to EN 14961-2; 

 C2 compressed wood (e.g. briquettes without additives, made of wood and/or bark particles; natural 

binding agents such as molasses, vegetable paraffins and starch are permitted), briquettes according to 

EN 14961-3; 

 D sawdust with moisture content w ≤ 50 %; 

 E non-woody biomass, such as straw, miscanthus, reeds, kernels and grains according to EN 14961-6. 

1.2.2 Fossil fuels 

 a bituminous coal; 

 b brown coal; 

 c coke; 

 d anthracite. 

1.2.3 Other solid fuels 

 e such as peat or processed fuels, according to EN 14961-1. 

2 Normative references 

The following documents, in whole or in part, are normatively referenced in this document and are 

indispensable for its application. For dated references, only the edition cited applies. For undated references, 

the latest edition of the referenced document (including any amendments) applies. 

EN 287-1, Qualification test of welders — Fusion welding — Part 1: Steels

EN 303-1:1999+A1:2003, Heating boilers — Part 1: Heating boilers with forced draught burners — 

Terminology, general requirements, testing and marking

EN 304:1992+A1:1998+A2:2003, Heating boilers — Test code for heating boilers for atomizing oil burners 

EN 1561, Founding — Grey cast irons

EN 1563, Founding — Spheroidal graphite cast irons

EN 10025-1, Hot rolled products of structural steels — Part 1: General technical delivery conditions

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EN 10027-2, Designation systems for steels — Part 2: Numerical system

EN 10028-2, Flat products made of steels for pressure purposes — Part 2: Non-alloy and alloy steels with 

specified elevated temperature properties

EN 10028-3, Flat products made of steels for pressure purposes ― Part 3: Weldable fine grain steels, 

normalized 

EN 10029, Hot rolled steel plates 3 mm thick or above — Tolerances on dimensions and shape 

EN 10088-2, Stainless steels — Part 2: Technical delivery conditions for sheet/plate and strip of corrosion 

resisting steels for general purposes

EN 10120, Steel sheet and strip for welded gas cylinders 

EN 10204, Metallic products — Types of inspection documents

EN 10216-1, Seamless steel tubes for pressure purposes ― Technical delivery conditions ― Part 1: Non-alloy 

steel tubes with specified room temperature properties

EN 10222-2, Steel forgings for pressure purposes — Part 2: Ferritic and martensitic steels with specified 

elevated temperature properties

EN 10226-1, Pipe threads where pressure tight joints are made on the threads ― Part 1: Taper external 

threads and parallel internal threads ― Dimensions, tolerances and designation 

EN 12828, Heating systems in buildings ― Design for water-based heating systems

EN 13284-1, Stationary source emissions — Determination of low range mass concentration of dust — Part 1: 

Manual gravimetric method 

EN 13384-1:2002+A2:2008, Chimneys — Thermal and fluid dynamic calculation methods — Part 1: 

Chimneys serving one appliance 

EN 13501-1, Fire classification of construction products and building elements ― Part 1: Classification using 

data from reaction to fire tests

EN 13501-2, Fire classification of construction products and building elements — Part 2: Classification using 

data from fire resistance tests, excluding ventilation services

EN 14597, Temperature control devices and temperature limiters for heat generating systems

EN 14778, Solid biofuels ― Sampling

EN 14961-1:2010, Solid biofuels ― Fuel specifications and classes ― Part 1: General requirements

EN 14961-2, Solid biofuels — Fuel specifications and classes — Part 2: Wood pellets for non-industrial use 

EN 14961-3, Solid biofuels — Fuel specifications and classes — Part 3: Wood briquettes for non-industrial 

use 

EN 14961-4, Solid biofuels ― Fuel specifications and classes ― Part 4: Wood chips for non-industrial use 

EN 14961-5, Solid biofuels ― Fuel specifications and classe ― Part 5: Firewood for non-industrial use

EN 14961-6, Solid biofuels ― Fuel specifications and classes ― Part 6: Non woody pellets for non-industrial 

use 

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EN 303-5:2012 (E) 

11 

EN 15270, Pellet burners for small heating boilers — Definitions, requirements, testing, marking 

EN 15456, Heating boilers ― Electrical power consumption for heat generators ― System boundaries ―

Measurements 

CEN/TS 15883, Residential solid fuel burning appliances ― Emission test methods

EN 60335-1, Household and similar electrical appliances ― Safety ― Part 1: General requirements 

(IEC 60335-1)

EN 60335-2-102:2006, Household and similar electrical appliances — Safety — Part 2-102: Particular 

requirements for gas, oil and solid-fuel burning appliances having electrical connections 

(IEC 60335-2-102:2004, modified)

EN 60730-1, Automatic electrical controls for household and similar use — Part 1: General requirements 

(IEC 60730-1)

EN 60730-2-5, Automatic electrical controls for household and similar use — Part 2-5: Particular requirements 

for automatic electrical burner control systems (IEC 60730-2-5) 

EN 61000-6-2, Electromagnetic compatibility (EMC) — Part 6-2: Generic standards — Immunity for industrial 

environments (IEC 61000-6-2)

EN 61000-6-3, Electromagnetic compatibility (EMC) — Part 6-3: Generic standards — Emission standard for 

residential, commercial and light-industrial environments (IEC 61000-6-3) 

EN ISO 228-1, Pipe threads where pressure-tight joints are not made on the threads — Part 1: Dimensions, 

tolerances and designation (ISO 228-1) 

EN ISO 228-2, Pipe threads where pressure-tight joints are not made on the threads — Part 2: Verification by 

means of limit gauges (ISO 228-2)

EN ISO 4063, Welding and allied processes — Nomenclature of processes and reference numbers 

(ISO 4063:2009, Corrected version 2010-03-01) 

EN ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method (ISO 6506-1) 

EN ISO 9606-2, Qualification test of welders — Fusion welding — Part 2: Aluminium and aluminium alloys 

(ISO 9606-2) 

EN ISO 12100, Safety of machinery ― General principles for design ― Risk assessment and risk reduction 

(ISO 12100)

EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories 

(ISO/IEC 17025) 

ISO 7-2, Pipe threads where pressure-tight joints are made on the threads — Part 2: Verification by means of 

limit gauges 

ISO 857-1, Welding and allied processes — Vocabulary — Part 1: Metal welding processes

ISO 857-2, Welding and allied processes — Vocabulary — Part 2: Soldering and brazing processes and 

related terms 

ISO 7005-1, Pipe flanges — Part 1: Steel flanges for industrial and general service piping systems

ISO 7005-2, Metallic flanges — Part 2: Cast iron flanges

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ISO 7005-3, Metallic flanges — Part 3: Copper alloy and composite flanges

3 Terms and definitions 

For the purposes of this document, the terms and definitions given in EN 303-1:1999+A1:2003 and the 

following apply. 

3.1 

maximum allowable operating pressure 

highest pressure at which the boiler can be operated safely 

Note 1 to entry: The maximum operating pressure is less than the test pressure and the type test pressure. 

3.2 

test pressure 

pressure to which all boilers and their parts are subjected during production at the manufacturers plant or 

during setting up by the installer 

3.3 

type test pressure 

pressure to which the heating boilers and their parts are first subjected before the start of mass production at 

the manufacturing plant 

3.4 

maximum allowable temperature 

maximum allowable water temperature of the heating boiler limited by safety devices 

3.5 

operating temperature 

temperature range at which the boiler can be operated under normal operating conditions, according to the 

setting on the boiler water temperature controller and the manufacturer's specifications 

3.6 

heat output 

Q

usable heat to water output delivered by a boiler per unit time in accordance with the requirements of this 

European Standard 

Note 1 to entry: The heat output data for solid fuel boilers are the average values over a related test period which are 

established in accordance with the requirements of this European Standard. 

3.7 

nominal heat output 

QN 

maximum continuous heat output specified by the manufacturer for a specific fuel in accordance with the 

requirements of this European Standard 

3.8 

minimum heat output 

Qmin

minimum heat output which is maintained automatically by the control device specified by the manufacturer for 

each type of fuel in accordance with the requirements of this European Standard 

Note 1 to entry: The minimum heat output can be achieved in intermittent operation. 

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3.9 

minimum continuous heat output 

QminC

minimum continuous heat output which is maintained automatically by the control device specified by the 

manufacturer for each type of fuel in accordance with the requirements of this European Standard 

3.10 

heat output range 

range of output between minimum and nominal to which the boiler can be adjusted and meets the 

requirements of this European Standard 

Note 1 to entry: The heat output range lies between nominal heat output and minimum heat output. 

3.11 

partial load 

T

quotient of heat output in the heat output range over the nominal heat output, expressed in percentage 

Note 1 to entry: 100

N

= ×

Q

Q T % 

3.12 

partial load operation 

operating condition/state of the boiler where the heat output is less than the nominal heat output and which is 

reached using an automatic control device 

3.13 

intermittent operation 

operating condition/state in which boiler heat output is controlled by the automatic connecting and 

disconnecting of the combustion air and/or fuel supply 

3.14 

heat input 

QB

amount of heat in unit time which is supplied to the furnace of the heating boiler by the fuel based on its net 

calorific value Hi

3.15 

boiler efficiency 

ηK

ratio of the delivered useful heat output to the heat input, expressed in percentage 

Note 1 to entry: 100

B

K = ×

Q

Q η % 

3.16 

draught 

pressure differential between the static air pressure in the place of installation and the static pressure of the 

exhaust gases (flue gas measuring section) 

3.17 

gas side resistance 

difference in pressure that exists between the combustion chamber and the flue gas outlet of the boiler (flue 

gas measuring section) 

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3.18 

gas side tightness 

tightness of the hopper, combustion chamber, flueways and the boiler sections traversed by the flue gas in 

relation to the place of installation 

3.19 

exit flue temperature 

temperature measured at the flue exit of the boiler (flue gas measuring section) 

3.20 

water side resistance 

pressure loss in the boiler measured at the flow and return connections of the boiler, with a volume flow 

corresponding to the nominal heat output 

3.21 

temperature controller 

device which detects and regulates the water flow temperature in the boiler 

3.22 

safety temperature limiter 

STB 

thermal cut out, protective control for heat generating systems which can only be reset manually or by a tool 

and which provides at least the following actions: type 2B, type 2K, type 2P and type 2V and optionally any of 

the following actions: type 2F and type 2N 

Note 1 to entry: The settings of this control are unchangeably fixed or can be fixed with a tool or a special tool. 

Note 2 to entry: Type 2K action will be considered to be provided if type 2N action is provided. 

Note 3 to entry: The actions are defined in EN 60730-1 and in EN 60730-2-9. 

3.23 

safety heat exchanger 

safety device for dissipating excess heat from the boiler to limit the boiler temperature to a specified maximum 

3.24 

thermal discharge safety device 

STW 

safety temperature limiter automatic reset (STW) used as a thermal bypass protection for solid fuel heat 

generating systems, which senses the heated media temperature and operates to cause energy to be carried 

off by opening a regulating unit, e.g. a valve 

Note 1 to entry: The settings of this control are unchangeably fixed. 

Note 2 to entry: Usually this is a mechanical device. This function could also be provided by an STW controlling a 

valve. 

3.25 

test fuel 

fuel of commercial quality used for testing heating boilers and characteristic of the type of fuel specified by the 

boiler manufacturer 

3.26 

stoking device 

device for feeding the fuel to the combustion chamber, which includes a safety device between stoking device 

and fuel line or an integral hopper 

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3.27 

stoking by hand 

fuel supplied by hand at intervals, depending on the burning rate or heat output 

3.28 

automatic stoking 

fuel supplied automatically, according to thermal output 

Note 1 to entry: Automatic stoking can be done continuously or intermittently. 

3.29 

combustion period 

necessary time taken by manual stoked boilers to burn the maximum fuel charge until the basic fire bed level 

specified by the manufacturer is reached again 

3.30 

nominal combustion period 

TB

combustion period at a nominal heat output 

3.31 

bypass device 

device which, in the open position, allows combustion gases to pass directly to the exhaust stack 

Note 1 to entry: A bypass device acts as a preheating aid or to overcome low temperature exhaust. 

3.32 

integral fuel hopper 

fuel hopper linked to the automatically stoked heating boiler 

Note 1 to entry: The filling of the hopper is a batch operation. 

3.33

fuel chamber 

part of a heating boiler stoked by hand supplying fuel for combustion without a connecting fuel line to an 

external fuel storage 

Note 1 to entry: The fuel chamber is the storage space necessary for obtaining a sufficient combustion duration. 

3.34 

combustion chamber 

boiler part for thermal preparation and/or burning of fuel 

Note 1 to entry: The combustion chamber may be part of the fuel chamber. 

3.35 

exhaust gas cleaning equipment 

techniques used for reducing air pollutants contained in the exhaust gas 

3.36 

ash chamber 

part of the boiler used for keeping combustion residues (ash/clinker) 

3.37 

accumulator storage tank 

container which stores excess heat (resulting from the difference between the boiler heat output and the 

actual heat load to the heating system) 

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3.38 

rapidly disconnectable firing system 

firing system by which, in all instances of operation and malfunction (e.g. such as power failures or sudden 

absence of heat reduction), the generation of heat can be interrupted so rapidly that hazardous operating 

states cannot occur either on the water side or on the firing side 

3.39 

hazardous operating state 

rise of the boiler temperature above 110 °C or, an accumulation of ignitable gases or gas mixtures (CO > 

volume fraction of 5 %) in the combustion chamber and/or in the flue gas passages of the boiler, a possible 

overheating of components, the escape of fire or gases into the place of installation and a back burning in the 

fuel supply 

3.40 

partly disconnectable firing system 

firing system where a part of the heat output can be briefly interrupted by the action of control and safety 

devices without causing hazardous operating states on the firing side 

3.41 

residual heat output 

remaining portion of heat output that is still transferred from the firing side to the water side after the control 

shut down or safety shut down of the boiler 

3.42 

ignition unit 

device used to ignite the fuel in the combustion chamber 

Note 1 to entry: Ignition can either be achieved manually, automatically or with a basic fire bed; and using, for 

example,a hot air fan, electric coil or electric glow plug. 

3.43 

back burning 

state in which the fuel ignites in direction to the fuel line and the burning spreads to the fuel storage or the 

integral hopper 

Note 1 to entry: Back burning can be caused by three driving forces: 

a) fuel ignition in direction to the fuel line or the integral hopper; 

b) spreading and ignition of hot and ignitable gases into the fuel line or the integral hopper; 

c) thermal conduction to the fuel line or the integral hopper. 

3.44 

back burning safety device 

one or more self-acting certificated device to avoid a back burning, including extinguishing installations 

3.45 

extinguishing installation 

device for the self-acting extinguishing of a back burn into the stoking device, fuel line or integral hopper 

3.46 

feeding direction 

direction the fuel follows when transported to the combustion chamber (either horizontally inclined/declined) 

3.47 

dust 

particles, of any shape, structure or density, dispersed in the gas phase at the sampling point conditions which 

may be collected by filtration under specified conditions after representative sampling of the gas to be 

analysed, and which remain upstream of the filter and on the filter after drying under specified conditions 

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3.48 

control shut-down 

process by which the fuel supply and/or combustion air supply is stopped as a result of a control function 

3.49 

safety shut-down 

process by which the fuel supply and/or combustion air supply is stopped immediately as a response of a 

safety device or the detection of a fault in a safety device 

3.50 

non-volatile lock out 

safety shut-down condition of a boiler, such that a restart can only be accomplished by a manual reset and by 

no other means 

3.51 

stand-by operation 

operating mode without any heat demand, whereby the system immediately starts up in the required mode as 

soon as there is be a heat demand 

4 Requirements 

4.1 General requirements 

Boilers shall be fire-resistant and safe to operate. They shall be made of non-combustible materials according 

to EN 13501-1 and shall be resistant to deformation. They shall be made such that: 

a) they can withstand stresses arising during normal operation; 

b) the heat carrier (water) does not become heated to a dangerous extent (≤ 110 °C); 

c) gases do not leak from the boiler or the stoking device or from an integrated hopper in dangerous 

quantities into the place of installation or into the fuel line; 

NOTE Safety requirements regarding harmful gas concentrations of course need to be considered. Both these 

elements however strongly depend on the place of installation and the fuel storage discharge system and therefore fall 

outside of the scope of this standard. This requirement is deemed to be fulfilled if the requirements of the leakage of the 

boiler and of the emissions are met and there is no visible smoke emerging from the boiler into the test room at normal 

operation during type test. 

d) flames do not flare out and embers do not fall out when the boiler is operated correctly; 

e) dangerous accumulations of combustible gases (> 5 % CO) in the combustion chamber and in the flues 

are prevented. 

For the evaluation of the hazardous situation, the CO-concentration in the flue gas measuring section should 

not exceed the critical values for a time period greater than 1 min. 

Combustible materials shall be allowed for the following: 

f) internal components of controls and safety equipment; 

g) operating handles; 

h) electrical equipment; 

i) components of accessory (e.g. burner cover); 

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j) additional or supplemental optical outer covers (e.g. an additional decorative cover). 

Component parts of Covers, operating controls, safety devices and electrical accessories shall fulfil the 

requirements of resistance against heat and fire in either EN 60335-1 or EN 60730-1. 

Component parts of Covers, operating controls, safety devices and electrical accessories shall be arranged in 

such a way that their surface temperatures, under steady state conditions, do not exceed those specified 

either by the manufacturer or in the component part standard. 

The materials for the parts subject to pressure shall be in accordance with generally accepted technical 

requirements. They shall be suitable for the purpose and intended use. Documented proof of mechanical and 

physical properties of materials used and their chemical composition shall be obtained from the supplier. 

The design of the boiler shall be such that it can be handled safely. It shall be designed and packaged so that 

it can be stored safely and without damage. 

Where the weight, size or shape of the boiler or its components prevents them from being moved by hand, 

they shall be fitted with means to lift them easily. 

Constructional parts accessible during use and maintenance shall be free from sharp edges and corners that 

might cause damage or personal injury during use or maintenance. 

Motors and fans shall be mounted in such a way as to minimize noise and vibration. 

4.2 Construction requirements 

4.2.1 Production documentation 

4.2.1.1 Drawings 

The drawings and/or the relevant documentation shall include at least the following information: 

a) the specification of the material; 

b) the welding process, the seam type (generally the symbol for the seam type is sufficient) and the welding 

fillers; 

c) the maximum allowable operating temperature, in °C; 

d) the maximum allowable operating pressure, in bar; 

e) the type test pressure, in bar; 

f) the nominal heat output or the heat output range for every boiler size, in kW, in accordance with the 

fuel(s) recommended for use in the boiler. 

4.2.1.2 Manufacturing controls 

A Quality Manual shall be compiled on the inspections and tests necessary during the manufacturing process. 

The manual shall: 

1) describe the inspection system; 

2) specify the person responsible for quality assurance; 

3) specify the necessary inspections and tests as well as the pertinent limit values and 

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4) lay down the requisite measuring and testing equipment and their inspection. 

4.2.2 Heating boilers made of steel and non-ferrous materials 

4.2.2.1 Execution of welding work 

Boiler manufacturers who carry out welding work shall meet the requirements of EN 287-1 and 

EN ISO 9606-2 as follows: 

 only welders who are qualified in the welding of the materials to be processed shall be used; 

 equipment shall be available to allow defect-free welding to be carried out; 

 supervision of the welding shall be carried out by staff qualified in welding (at least one supervisor shall 

be qualified). 

4.2.2.2 Welding seams and welding fillers 

The materials shall be suitable for welding. 

NOTE 1 The materials in Table 1 are suitable for welding and do not require additional heat treatment after welding. 

The welded seams shall not show any cracks or lack of fusion and shall be defect free over the whole crosssection for butt welds. One-sided fillet welds, and half Y-welds which have been welded through, shall be kept 

substantially free from bending stresses. Smoke tubes, inserted stays and similar components need not be 

counter welded. 

Double fillet welds are only permissible when sufficiently cooled. Projections into the flue gas side in areas of 

high thermal stresses shall be avoided. 

Corner welds, edge welds and similar welded connections, which shall only be subject to high bending 

stresses during production and operation, are to be avoided. 

When welding longitudinal stay bars or stay tubes, the shearing cross section of the fillet weld shall be 

1,2 times the required stay bar or stay tube cross sectional area. 

The permissible types of weld and appropriate material thicknesses are given in Table 2 and these 

parameters shall be met. 

Welding fillers shall be suitable for the material being used. 

NOTE 2 The terms given in Table 2 are in accordance with EN 22553; the reference numbers of welding processes are 

in accordance with ISO 857-1, ISO 857-2 and EN ISO 4063. 

4.2.2.3 Parts of steel subject to pressure 

The steels listed in Table 1 shall be used. 

Materials and wall thicknesses other than those specified shall only be used on the production of appropriate 

evidence, with regard to (at least) their equivalent corrosion resistance, heat resistance and strength to nonalloy steel at the material thicknesses specified in Table 1 for the particular application/usage. 

The specification of the materials shall be documented by a works certificate in accordance with EN 10204. 

These certificates shall be obtained by the boiler manufacturer. This does not apply to components, e.g. 

sockets up to DN 50, screws and nuts. 

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Table 1 — Materials 

References Material type Material numbers 

(in accordance with EN 10027-2)

EN 10025-1 E235 1.0308 

 S235JR 1.0037 

 S235JRG2 1.0038 

 S235J0 1.0114 

 S235J2G3 1.0116 

 S275JR 1.0044 

 S275J0 1.0143 

 S275J2G3 1.0144 

 S355J2H 1.0576 

 S355JR 1.0045 

 S355J0 1.0553 

 S355J2G3 1.0570 

 S355K2G3 1.0595 

EN 10216-1 P195TR1 1.0107 

 P235TR1 1.0254 

 P235GH 1.0345 

EN 10028-2 P265GH 1.0425 

EN 10028-3 P355NL1 1.0566 

 P295GH 1.0481 

 P355GH 1.0473 

 16Mo3 1.5415 

 15NiCuMoNb5-6-4 1.6368 

 13CrMo4-5 1.7335 

 10CrMo9-10 1.7380 

 11CrMo9-10 1.7383 

EN 10120 P245NB 1.0111 

 P265NB 1.0423 

 P310NB 1.0437 

 P355NB 1.0557 

EN 10088-2 X5CrNi18-10 1.4301 

 X5CrNi17-12-2 1.4401 

 X2CrNiM017-13-2 1.4404 

 X6CrNiTi18-10 1.4541 

 X6CrNiNb18-10 1.4550 

 X2 CrMnNiN 22-5-2 1.4162 

 X2 CrNiN 23-4 1.4362 

 X2 CrNiMoN 22-5-3 1.4462 

 X1 NiCrMoCuN 25-20-7 1.4529 

 X1 NiCrMoCu 25-20-5 1.4539 

 X6CrNiMoTi17-12-2 1.4571 

 X6CrNiMoNb17-12-2 1.4580 

 X3CrNiMo17-3-3 1.4436 

EN 10222-2 P245GH 1.0352 

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Table 2 — Weld joints and welding processes (1 of 3) 

No. Term Material 

thickness 

(mm)

Welding 

process a Remarks 

1.1 Square butt weld 

both sides: 

≤ 6 (8) 135 

12 

131 

(111) 

Permissible up to t = 8 mm on 

use of deep penetration 

electrodes or welding on both 

sides 

1.2 Square butt weld ≥ 6 up to 12 12 Root gap b = 2 mm to 4 mm 

with stiffener, power holder 

necessary 

1.3 Square butt weld (double) > 8 up to 12 135 

12 

(111) 

Root gap b = 2 mm to 4 mm 

Deep penetration electrodes 

shall be used for manual 

electro welding 

1.4 Single-V butt weld up to 12 (111) Weld preparation V-seam 60° 

1.5 Single-V butt weld up to 12 135 

12 

Weld preparation 

V-seam 30° to 50° 

depending on thickness of 

material 

1.6 Double-V butt weld greater 

than 12 

135 

12 

Weld preparation 

double V-seam 30° to 50° 

depending on material 

thickness 

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Table 2 (2 of 3)

1.7 Overlap welding ≤ 6 135 

12 

Welds of this type are to be 

kept largely free from bending 

stresses. Not suitable for 

directly fired wall parts s = t

1.8 Overlap welding (continued) ≤ 6 135 

12 

(111) 

Not suitable for directly fired 

wall parts s = t

2 Fillet weld ≤ 6 135 

12 

(111) 

Welds of this type are to be 

kept largely free from bending 

stresses a = t

2.1 Double fillet weld ≤ 12 

>12 

135 

12 

(111) 

135 

12 

(111) 

a = t 

a = 2/3 t

2.2 Double-bevel butt weld ≤ 12 

>12 

135 

12 

(111) 

135 

12 

(111) 

a = t 

a = 2/3 t

2.3 Single-bevel butt weld ≤ 12 

> 12 

135 

12 

(111) 

135 

12 

For (111) β = 60° 

For 135,12 β = 40° to 50° 

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Table 2 (3 of 3)

2.4 Single-bevel butt weld ≤ 12 135 

12 

(111) 

For (111) β = 60° 

For 135,12 β = 40° to 50° 

2.5 ≤ 12 135 

(111) 

Tube end shall not project 

beyond fillet weld if it is 

subjected to heat radiation 

2.6 ≤ 6 135 

(111) 

Welding in of tube under high 

thermal stress a ≥ t

2.7 135 

(111) 

Welding in of tube under high 

thermal stress 

For (111) β = 60° 

For 135 β = 40° to 50° 

a

 Reference numbers of welding processes are in accordance with ISO 857-1, ISO 857-2 or EN ISO 4063. 

Reference number 

12 

111 

131 

135 

141 

Process

Submerged arc welding 

Metal-arc welding with covered electrode 

Metal-arc inert gas welding; MIG welding 

Metal-arc-active gas welding; MAG welding 

Tungsten inert gas arc welding; TIG welding 

Laser Welding is also accepted if the requirements of EN ISO 15609-4, EN ISO 15614-11, EN ISO 13919-1 

and EN ISO 13919-2 are fulfilled. 

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4.2.2.4 Minimum wall thicknesses 

The minimum wall thicknesses listed in Table 3 have been specified in order to take into account the following: 

a) the maximum allowable operating pressure; 

b) the nominal heat output; and 

c) the material properties. 

For boilers which consist of a combination of individual geometrically identical parts (sections), the 

requirements of the minimum wall thickness for the complete range of the nominal heat output of the boiler 

shall be in accordance with the individual boiler sections as specified in Table 3. 

The wall thickness tolerance for carbon steels shall be as specified in EN 10029. 

The minimum wall thicknesses according to Table 3 apply to pressure-loaded sheets, tubes (except 

immersion coils and safety heat-exchangers) and forgings. Smaller wall thicknesses shall be permitted upon 

the production of evidence demonstrating equivalence with regard to corrosion, heat resistance and strength. 

Table 3 — Minimum wall thicknesses 

Nominal heat output Carbon steels 

Stainless and corrosion 

protected steels 

a b c d e a b c d e 

kW mm mm mm mm mm mm mm mm mm mm

QN ≤ 100 5 4 3,2 3 4 3 2 1,5 2 3 

100 < QN ≤ 300 5 4 3,2 4 4 3 2 1,5 2 3 

300 < QN ≤ 500 6 5 3,2 4 4 4 2 1,5 2 3 

Column a: for walls of the filling and combustion chamber in contact with fire and water 

Column b: for walls of the convection heating surfaces outside the combustion chamber (except circular tubes) 

Column c: for circular tubes in the convection heating surface area outside the combustion chamber 

Column d: for walls which are only in contact with water 

Column e: for water cooled grate tubes 

4.2.3 Boilers made of cast materials 

4.2.3.1 General 

The manufacturer shall have personnel and equipment capable of carrying out the necessary material tests. 

During the manufacture of the boiler and other cast iron parts subject to pressure, the following tests shall be 

carried out using separate cast test pieces for each batch: 

1) tensile test in accordance with EN 1561 and EN 1563; the values given in Table 4 are to be confirmed by 

the tensile test; 

2) chemical analysis (C, Si, Mn, P, S); 

3) brinell hardness test in accordance with EN ISO 6506-1; 

4) izod impact (for graphite iron). 

The results of the tests shall either be recorded in registers countersigned by the works tester responsible, or 

works certificates in accordance with EN 10204 shall be drawn up. Works certificates and registers shall be 

kept for at least five years by the manufacturer and shall be accessible for examination. 

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Repairs undertaken by the welding of parts subject to pressure is not permissible. 

4.2.3.2 Cast iron parts subject to pressure 

The mechanical properties of cast iron used for parts subject to pressure shall, as a minimum, correspond to 

the values listed in Table 4. 

Table 4 — Minimum mechanical requirements for cast irons 

Grey cast iron (in accordance with EN 1561) 

- Tensile strength Rm ≥ 150 N/mm2

- Brinell hardness 160 HB to 220 HB 

Spheroidal graphite cast iron (in accordance with EN 1563) 

- Tensile strength Rm ≥ 400 N/mm2

- Izod impact ≥ 23 J/cm2

4.2.3.3 Minimum wall thicknesses 

The wall thicknesses given in the production drawing shall not be less than the minimum wall thicknesses 

listed in Table 5. The actual minimum wall thicknesses during manufacture of the boiler sections and other 

parts subject to pressure shall be more than 0,8 times the thickness given in the drawing. 

Smaller wall thicknesses shall be permitted upon the production of evidence demonstrating equivalence with 

regard to corrosion, heat resistance and strength for the particular application/usage. 

Table 5 — Minimum wall thicknesses of boiler sections of cast material 

Nominal heat output 

kW

Minimum wall thicknessa for cast iron with 

lamellar graphite spheroidal graphite/annealed ferritic 

mm mm 

QN ≤ 30 3,5 3,0 

30 < QN ≤ 70 4,0 3,5 

70 < QN ≤ 300 4,5 4,0 

300 < QN ≤ 500 5,5 5,0 

a

 Heating boilers for fossil fuels; for biogenic fuels: add 0,5 mm. 

For boilers which consist of a combination of individual geometrically identical parts (sections) the 

requirements of the minimum wall thickness for the complete range of the nominal heat output of the boiler 

shall be in accordance with the individual boiler sections in accordance to Table 5. 

4.2.4 Design requirements 

4.2.4.1 Venting of the water sections 

The boiler and its components shall be designed in such a way that their respective water sections can be 

fully vented. 

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The boiler shall be designed in a way that under normal operation in accordance with the manufacturer's 

instructions no undue boiling occurs. 

NOTE Boiling can be detected by boiling noise. 

4.2.4.2 Cleaning of heating surfaces 

The heating surfaces shall be accessible from the flue gas side for inspection and cleaning with chemical 

agents and brushes. A sufficient number and appropriate arrangement of cleaning openings shall be provided. 

If special tools (for example special brushes) are required for cleaning and maintenance of the boiler, these 

shall be supplied. 

4.2.4.3 lnspection of the flame 

A facility shall be provided which allows inspection of the flame or fire bed. If this facility is a door, then 

hazard-free inspection shall be possible. 

NOTE The facility of an inspection window is recommended. 

4.2.4.4 Water tightness 

Holes for screws and similar components which are used for the attachment of removable parts shall not enter 

into spaces through which water flows. This does not apply to pockets for measuring or control and safety 

equipment. 

4.2.4.5 Replacement parts 

Replacement and spare parts (e.g. inserts, shaped firebricks, turbulators etc.) shall be designed, made or 

marked in such a way that their installation shall be correct in accordance with the manufacturer's instructions. 

4.2.4.6 Boiler shell tappings 

Boiler shell tappings shall comply with EN 10226-1, ISO 7-2, EN ISO 228-1, EN ISO 228-2; flange 

connections shall comply with ISO 7005-1, ISO 7005-2 and ISO 7005-3. The arrangement of the tappings 

shall be such that they are easily accessible and the function of each respective connection can be 

adequately fulfilled. There shall be sufficient space around the connection to allow the installation of the 

connecting pipes (flanges, bolts) with the necessary tools. 

Threaded pipe connections above 2 inches (DN 50) are not recommended. Threaded pipe connections with 

nominal diameters above 3 inches (DN 80) shall not be permitted. This information shall be supplied with the 

boiler. If connections are fitted with flanges, the mating flanges and seals shall also be supplied except where 

standardised flanges and seals are available. 

The minimum size for flow outlet shall be DN 20. 

The boiler shall have at least one connection for filling and emptying. This connection may be common. The 

size of the connection shall be as a minimum: 

 G 1/2 for nominal heat outputs up to 70 kW; 

 G 3/4 for nominal heat outputs above 70 kW. 

It is possible to provide these connections outside the boiler if satisfactory filling and emptying of the boiler can 

be assured. 

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4.2.4.7 Immersion pockets for control and indicating equipment, and safety temperature limiter 

Every boiler shall be equipped with at least one immersion pocket which is used for temperature control, a 

safety temperature limiter and a thermometer. If a threaded pipe connection is required, the minimum nominal 

diameter shall be G 1/2. 

Alternative arrangements are allowed, provided that the control devices are supplied with the boiler, and that 

they cannot be substituted by other components. 

The immersion pockets shall be designed so that an unintended change of position of the temperature sensor 

is avoided. 

The position of the immersion pocket shall be chosen in such a way that the highest temperature of the boiler 

water is recorded with sufficient accuracy. Where additional connections for safety devices such as a pressure 

detector, manometer, low water cut-out device or a safety valve are provided, then their size (especially the 

size of the safety valve), shall be determined according to the output of the boiler. 

NOTE For further information on safety valves, see EN 12828. 

4.2.4.8 Thermal insulation 

All boilers shall be fitted with thermal insulation. The thermal insulation shall withstand normal thermal and 

mechanical stresses. It shall be made of non-combustible material and shall not give off fumes during normal 

running. 

4.2.4.9 Water side resistance of the boiler 

The water side resistances are to be determined for those flows which correspond to the nominal heat output 

with two temperature differences of 10 K and 20 K between the flow and return connections of the boiler. The 

results are to be stated in mbar for each boiler size and shall correspond to the values indicated by the 

manufacturer. 

4.2.4.10 Integral fuel hopper 

A boiler with integral fuel hopper shall be made of fire resistant material according to EN 13501-2. The volume 

shall be limited to a maximum of 1,5 m3. The hopper shall be designed in such a way that the fuel moves 

freely until the hopper is empty. 

4.2.4.11 Fuel chamber 

The fuel chamber shall be designed in such a way that the fuel moves freely and the duration of the 

combustion period is assured. 

4.2.4.12 Ash chamber 

The capacity of the ash chamber shall be adequate for a combustion period of at least 12 h using the 

stipulated fuel at nominal heat output. It shall be designed to ensure the unobstructed flow of combustion air 

under the grate. 

If the system is designed with devices for automatic ash and clinker removal, the above requirement shall be 

considered as met. 

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4.3 Safety requirements 

4.3.1 General 

Potential hazards caused by the boiler, including the operation of the firing system and any stoking device, 

shall be avoided by either constructional means or by the use of safety devices. Safety shall be maintained in 

the event of possible failures in the safety device itself. 

The manufacturer shall undertake a risk assessment covering all potential hazards of the boiler and the 

measures how to avoid or control them in a safety concept. Control functions within the safety concept shall 

be classified and realized accordingly. The risk assessment shall be performed according to EN ISO 12100 

with particular emphasis on the type of the boiler and the fuel fired. 

Control functions are classified as follows. 

Class A: Control functions which are not intended to be relied upon for the safety of the application. 

Class B: Control functions which are intended to prevent an unsafe state of the appliance. Failure of the 

control function will not lead directly to a hazardous situation. For devices used in a class B control function, a 

single fault assessment of the device including use of software class B according to EN 60730-1 is required. 

Class C: Control functions which are intended to prevent special hazards such as explosion or whose failure 

could directly cause a hazard in the appliance. For devices used in a class C control function, a second fault 

assessment of the device including use of software class C according to EN 60730-1 is required. 

In case of safety routines realised in a programmable logic control the software shall meet the requirements of 

the appropriate software class B or C (including fault assessment according to EN 60730-2-5 in connection 

with EN 60730-1). 

This risk assessment shall cover at least the following: 

 elements given in 4.3.4 to 4.3.9; 

 boiler functions, including start-up, purge, ignition, flame supervision, flue gas flow, control of heat 

demand and combustion control. 

In the risk assessment, one of the above mentioned classifications of the control function shall be allocated to 

any identified hazard. 

The actuation of any control function class B or class C shall at least result in cutting off the fuel feed. 

4.3.2 Manual stoking 

Boilers with manual stoking shall be designed in such a way that, when the boiler is operated in accordance 

with the boiler manufacturer’s operating instructions, the operator does not run the risk of a hazardous 

operation mode. Such a mode might result in an injury when opening the fuel chamber door or the combustion 

chamber (e.g. by ignition of gases). 

4.3.3 Safety against back burning for automatic stoked boilers 

4.3.3.1 General 

Automatic stoking systems shall be designed to prevent back burning. 

The hazard of back burning is classified as a risk corresponding to safety level C in accordance with 4.3.1 and 

is related to the driving forces thermal conductance, backflow of ignitable gases and fire propagation 

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backwards (see 4.3.3.2, 4.3.3.3 and 4.3.3.4). Back burning shall be avoided by constructional means and the 

implementation of one or more back burn safety devices. 

NOTE The handling of the risk for back burning at safety level C includes the specification that sufficient safety 

measures need to be available. 

Adequate constructional means or safety devices shall: 

a) work always in the closed circuit current principle; 

b) avoid a back burning in the state of loss of power supply; 

c) avoid a back burning in the state of failure of stoking device or interruption of stoking device. 

In order to ensure that safety against back burning is adequately addressed, a risk assessment shall be 

undertaken. This assessment shall document the means employed to avoid the three driving forces for back 

burning and how they match the tested boiler. The documentation of the means employed shall include the 

specification of any chosen safety device. 

At least one of the safety systems shall continue to provide protection in the event of interruption of the fuel 

feed (e.g. blockage of the feed screw). 

The following mechanisms shall be avoided: 

d) Thermal conductance (4.3.3.2); 

e) Back flow of ignitable combustion gases (4.3.3.3); 

f) Fire propagation into fuel line (4.3.3.4). 

4.3.3.2 Thermal conductance 

The surface temperature of the stoking device of the boiler (without insulation) or integrated hopper shall not 

exceed 85 °C in any operating state or in case of a failure. If this criterion is fulfilled by constructional means, 

no additional safety device is necessary. 

Thermal conductance shall be verified during the tests specified in 5.7 (thermal performance for nominal load 

and partial load), 5.13 to 5.16 and after the stopping of the stoking device of the boiler, with a permanent 

temperature measurement until a maximum is reached. For further information on verification of this 

requirement, see 5.16.4. 

Accepted solutions to prevent overheating in the stoking device due to thermal conductance are: 

 an extinguishing device e.g. water sprinkler system and a safety temperature limiter adjusted to a 

maximum of 95 °C; 

 an emergency discharge device emptying the stoking device without overfilling the boiler; which is 

reacting below 95 °C (alternatively 20 K increase to standard operation conditions); 

 a stoking device which is cooled by a water circuit and the temperature of the water is limited by a cut out 

(e.g. water circuit is part of boiler circuit). 

Accepted solutions to prevent overheating in the integrated hopper due to thermal conductance in 

combination with accepted solutions for stoking devices are: 

 an extinguishing device directly in the hopper e.g. water sprinkler system and an STB adjusted to a 

maximum of 95 °C; 

 sufficient insulation of the hopper from hot parts of the boiler; 

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 naturally ventilated space between hopper and boiler body (separate casing). 

Criteria to verify the design of accepted solutions are listed in Table B.1. 

No test needs to be performed according to 5.16.4 if the chosen design is an accepted solution and the risk 

assessment proves the suitability for the boiler burner unit and the control algorithm interaction. If the risk 

assessment fails, further tests shall be required. 

4.3.3.3 Back flow of ignitable combustion gases into the fuel line or integral hoppers 

No significant flow of combustion gases in an ignitable concentration or carrying a critical amount of energy to 

ignite wood (e.g. sparks or hot gases) shall pass the constructional means or safety device(s) into the fuel line 

or into the hopper. Due to other safety reasons (for example to hinder poisoning by CO), any back flow of 

combustion gases shall be avoided (see 4.1). 

NOTE 1 Indications for significant back flow might include: 

a) a temperature rise of more than 20 K compared to operation without back flow; 

b) CO concentration of more than 1 vol. % CO (dry) in the fuel line caused by any operational status or failure; 

c) accumulation of smoke in an integrated hopper. 

This requirement applies during the tests according to 5.7 (thermal performance for nominal load and partial 

load including ignition, start up, continuous operation and shut down) and 5.13 to 5.16. 

Accepted solutions to prevent back flow in the fuel line are listed as follows. 

 Safety device to maintain a continuous seal between the stoking device and the fuel line, e.g. cell feeder. 

 Safety device to seal the fuel line not during fuel supply but during all other phases of operation (e.g. lid) 

in combination with a boiler operating with a negative pressure (tightness requirements in closed state 

identical to continuously sealing safety devices). 

 Tight fuel hopper lid in combination with pressure equalization that works during normal operation and in 

case of start up, shut down or power loss. Diffusion of hot gasses into the hopper shall be avoided by a 

connection for pressure equalization between the combustion air supply and the fuel hopper. The 

dimension of the connection shall only be sufficient to equalize pressure, not to accelerate fire 

propagation. Hopper lid shall be fitted with an interlock switch (according to H27 of EN 60730-2-5) which 

stops combustion air supply in case of an open lid. 

 Tight fuel hopper lid in combination with negative pressure operation of the boiler. Diffusion of hot gasses 

into the hopper shall be avoided by natural draught (e.g. inclined auger). The hopper lid shall be fitted 

with an interlock switch (according to H27 of EN 60730-2-5) which stops combustion air supply in case of 

an open lid. 

 Use of directed flow to create stable pressure conditions, e.g. injector, safety device to control fan rotation 

of supply fan or relevant pressure, which closes the fuel supply in case of failure. 

NOTE 2 Other solutions include the use of a flue gas fan to assure negative pressure condition in the boiler compared 

to pressure in the fuel line or hopper. The flue gas fan operation is controlled by a safety device for rotation or for pressure 

in combination with an additional safety device that prevents back flow in case fan failure or power loss. 

Criteria to verify the design of accepted solutions are listed in Table B.1.

No test needs to be performed according to 5.16.4 if the chosen design is an accepted solution and the risk 

assessment proves the suitability for the boiler burner unit and the control algorithm interaction. If the risk 

assessment fails, further tests shall be required. 

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4.3.3.4 Fire propagation into the fuel line or integral hopper 

Fire propagation into the fuel line or integral hopper shall be avoided in any operational state or in case of any 

failure. This does not include the thermal reaction of a small amount of fuel at the end of the stoking device, if 

there is no further reaction into the fuel line. 

NOTE Indication for significant fire propagation might include: 

a) a temperature raise of more than 20 K in the stoking device above normal operation; 

b) a temperature of more than 85 °C on the surface of the stoking device; 

c) an accumulation of smoke in an integral hopper. 

This requirement shall be proven during the tests according to 5.7 (thermal performance for nominal load and 

partial load) and 5.13 to 5.16 with a permanent temperature measurement until the maximum temperature is 

reached. 

Accepted solutions to hinder fire propagation to the fuel line are listed as follows. 

 An extinguishing device, e.g. water sprinkler system and an STB adjusted to a maximum of 95 °C. 

 A safety device to seal continuously the supply line and with a sufficient fuel free distance and fuel free 

cross section, (e.g. cell feeder, rotary air lock) in combination with a design to prevent overfilling. 

 A safety device to seal the fuel line not during fuel supply but during all other phases of operation (e.g. 

lid) in combination with a boiler operating with a negative pressure (tightness requirements in closed state 

identical to continuously sealing safety devices), in combination with a design to prevent overfilling and 

with a sufficient fuel free distance and fuel free cross section. 

 An emergency discharge device emptying the stoking device without overfilling the boiler, which is 

reacting at a temperature limit not exceeding 95 °C (alternatively 20 K increase to standard operation 

conditions). 

 Inclined auger in combination with fuel transport slide to/in the combustion chamber and a safety limiter 

reacting at a temperature not exceeding 95 °C. 

Criteria for accepted solutions to verify the design are listed in Table B.1. 

No test needs to be performed according to 5.16.4 if the chosen design is an accepted solution and the risk 

assessment proves the suitability for the boiler burner unit and the control algorithm interaction. If the risk 

assessment fails, further tests shall be required. 

4.3.3.5 Alternative verification of safety against back burning 

In case of any deviations regarding 4.3.3.2 to 4.3.3.4, the safety against back burning shall be verified 

according to the following procedures, combining a risk assessment including reliable tests of the alternative 

safety devices with reference to the criteria in 5.16.1. 

If: 

 no accepted solution is chosen, or 

 the risk assessment ensures no suitability of a accepted solution for the boiler design, or 

 the accepted solutions against back burning are not applicable (e.g. the suitability of constructional 

means or devices or the tightness criterion for certain boiler designs), 

further tests shall be performed (see 5.16.5). 

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The test shall be documented by the third party laboratory in a report which includes the description of the test 

sample and the test installation, the way to perform the back burning test, the test conditions and the test 

results. 

4.3.4 Safety against fuel overload of the boiler or interruption in fuel supply 

During start up and continuous operation of the boiler with the fuel feed rate of the stoking device set at 

maximum capacity or interruption of the stoking device, no dangerous situation shall occur. 

The test at overload mode according to 5.16.2 may be omitted if a safety device, safety level C according to 

4.3.1, prevents an overload mode. 

The boiler shall be equipped with a safety device that stops the fuel supply in the event that there is either 

insufficient or no combustion in the burner head. 

The test for interruption of fuel supply according to 5.16.2 may be omitted if a safety device, safety level B or 

C according to 4.3.1, is used. 

In the ignition phase, a safety device shall stop the fuel supply after a safety time which shall be declared by 

the manufacturer of the burner start up function, if there is no or insufficient combustion. A failure in the safety 

device to detect insufficient combustion shall not lead to a dangerous situation. 

4.3.5 Safety against lack of air supply or insufficient combustion 

If the air supply includes fan assistance or adjustable devices to control the cross section of the air inlet, the 

tests according to 5.16.3 shall be performed. Neither a combination of a failure of the fan and the malposition 

of the adjustable devices nor the malpositions of adjustable devices with separate actuators at the same time 

shall be taken into account. 

The CO concentration in the boiler shall not exceed 5 % volume. 

4.3.6 Surface temperatures 

The surface temperature on the outside of the boiler (including the bottom and doors but not including the flue 

gas outlet and maintenance openings of natural draft boilers) shall not exceed the room temperature by more 

than 60 K when tested in accordance with 5.12. The requirement for the bottom is not applicable for instances 

when the manufacturer declares that the boiler is to be installed on a non-combustible base. 

When tested in accordance with 5.12, the surface temperature of operating levers and all parts which shall be 

touched by hand during operation of the boiler shall not exceed the room temperature by more than the 

following values: 

 35 K for metals and similar materials; 

 45 K for porcelain and similar materials; 

 60 K for plastics and similar materials. 

4.3.7 Leakage of the combustion system 

For boilers designed to operate with a positive pressure in the combustion chamber when tested in 

accordance with 5.6 at a test-pressure of 1,2 times the gas side resistance at nominal heat output, the 

leakage rate based on mass flow shall not exceed 2 % of the flue gas mass flow at the nominal heat output. 

The gas side resistance shall be determined with the fuel chamber filled to maximum capacity (as specified by 

the manufacturer). 

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NOTE For boilers designed to operate with negative pressure, the leakage rate measured according to 5.6 

characterises the boiler. 

4.3.8 Temperature control and limiting devices 

4.3.8.1 General 

The control and safety devices described in the sections below as well as the appropriate installation options 

shall be provided for each boiler, depending on the type of firing system and the type of protection provided for 

the installations in which the boiler is to be fitted. The equipment required in each case shall be supplied by 

the boiler manufacturer along with the boiler. If equipment is not supplied, precise specifications shall be given 

in the installation instructions, in particular the Iimit values and time constants for the safety temperature 

limiter. 

4.3.8.2 Temperature control and limiting devices for open vented systems 

When used in physically protected heating installations (the temperature is limited by installation pressure) the 

following equipment shall be provided, according to the requirements of EN 14597: 

 a temperature controller; 

 a safety temperature limiter (manual reset). 

The safety temperature limiter is not necessary in cases where the firing system is neither rapidly nor partly 

disconnectable. In these cases (e.g. for boilers without automatic force draft), the excess heat is dissipated in 

the form of steam through the open vented connection with the atmosphere. 

4.3.8.3 Temperature control and limiting devices for closed vented system 

When used in thermostatically protected heating installations, the firing system shall be either rapidly or partly 

disconnectable; and/or the heat or residual heat output not absorbed by the heating system shall be 

dissipated reliably using a safety heat exchanger or equivalent devices. Accordingly, a distinction is to be 

made between the following equipment variants, according to the requirements of EN 12828: 

a) The firing system is rapidly disconnectable; the necessary equipment shall consist of: 

1) a temperature controller; 

2) a safety temperature limiter (manual reset). 

b) The firing system is partly disconnect able; the necessary equipment shall consist of: 

1) a temperature controller; 

2) a safety temperature limiter (manual reset); 

3) a thermal discharge safety device in accordance with 4.3.8.4 for dissipating the maximum heat 

output possible in the event of a malfunction. 

c) The heating system is not disconnectable and the nominal heat output is < 100 kW; the necessary 

equipment shall consist of: 

1) a temperature controller; 

2) a thermal discharge safety device in accordance with 4.3.8.4 for dissipating the maximum heat 

output possible in the event of a malfunction. 

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If the requirements are not fulfilled, the boiler shall be installed in an open vented system according to 

EN 12828. 

4.3.8.4 Devices for dissipating excess heat 

The safety heat exchanger or other devices for dissipating excess heat shall ensure that a maximum boiler 

water temperature of 110 °C is not exceeded in accordance with 5.14. 

For this purpose, a thermal discharge safety device shall be used such as an STW type Th according to 

EN 14597, in combination with a heat exchanger integrated in the boiler. Admissible heat exchangers include 

storage or circulatory water heaters, provided they are designed and sized in such a way that the heat can be 

transferred without any additional auxiliaries and outside energy. Fixed integrated circulatory water heaters 

cannot be used as operating water heaters but only as safety heat exchangers. Additionally, the following 

conditions shall be met: 

 the thermal safety discharge device and the heat exchanger shall be adapted to the design and thermal 

properties of the boiler and be capable of reliably dissipating the maximum heat output possible in the 

event of malfunction or, in the case of partly disconnectable heating systems, the residual heat output; 

 if a storage water heater is used as the heat exchanger, it shall be designed so that it meets the 

aforementioned condition at its maximum operating temperature; 

 in the case of safety heat exchangers used exclusively to dissipate heat in the event of malfunctions, the 

thermal safety discharge device shall be fitted ahead of the heat exchanger in the cooling water inlet. 

Other solutions are not excluded provided they comply with the protection objectives and safety standards 

described above. In principle however, all devices for dissipating excess heat are only admissible for: 

 boilers without a disconnectable firing system with rated heat outputs of maximum 100 kW; 

 boilers with a partly disconnectable firing system with residual heat outputs of up to 100 kW. 

4.3.9 Heating boiler accessories 

4.3.9.1 General 

If the boiler is factory equipped with additional fittings which need to be serviced to ensure their correct 

operation and the safety of the boiler, the design shall ensure ease of access without requiring extensive 

dismantling work. 

4.3.9.2 Electrical safety 

The electrical safety of the boiler and the interfaces (e.g. connectors) between control devices shall comply 

with EN 60335-2-102. 

The electrical safety of control devices shall comply either with EN 60335-2-102, with EN 60730-1 or its 

relevant part 2 or with the electrical requirements of the standards listed in Annex ZBB of 

EN 60335-2-102:2006. 

For abnormal operation as fault condition according to 19.11.2 f) of EN 60335-2-102:2006 (failure of 

integrated circuits), only output signals which cause only one malfunction in one actuator shall be considered 

as relevant. Combinations of output signals which cause malfunction in more than one actuator are not 

considered relevant in the sense of abnormal operation because it is unlikely that any hazardous situation can 

occur. 

The documentation of the electrical connections for the individual components shall be provided by means of 

an electrical wiring and connection diagram. 

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4.3.9.3 Electromagnetic compatibility 

The EMC requirements shall be fulfilled in accordance with EN 61000-6-2 and EN 61000-6-3. 

For this testing, it is permissible to use an adapted version of the boiler software for simulating boiler 

operation. 

4.4 Performance requirements 

4.4.1 General 

The following performance requirements shall be assessed in tests using the appropriate test fuel(s) specified 

in Table 7. These shall be selected to represent the recommended fuel(s) which it is claimed the boiler can 

burn. 

NOTE The nominal heat output and the heat output range might vary depending on the fuel. 

The requirements for the boiler efficiency and the emission limits are divided into 3 classes. To meet the class 

requirements, all the efficiency and emission limits of that class shall be fulfilled. 

4.4.2 Boiler efficiency 

The boiler efficiency, when tested in accordance with 5.7, 5.8 and 5.10, shall not be less than the formula 

shown in Figure 1 for the nominal heat output. For boilers above 100 kW, the requirement for class 4 is given 

at 84 % and class 5 is given at 89 %. For boilers above 300 kW, the requirement of class 3 is given at 82 %. 

η K

Q

Key 

Q heat output in kW 1 class 3 

η K efficiency in % 2 class 4 

 3 class 5 

Figure 1 — Boiler efficiency in percent 

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class 5 Q < 100 kW 

ηK = 87 + log Q (in percent) (1) 

class 4 Q < 100 kW 

η K = 80 + 2 log Q (in percent) (2) 

class 3 Q < 300 kW 

η K = 67 + 6 log Q (in percent) (3) 

where η K is the boiler efficiency in percent and Q is the heat output in kilowatts. 

NOTE 1 Q is heat output QN respectively minimum continuous heat output Qmin . 

NOTE 2 The legislation of some countries requires the efficiency values to be given on a gross basis. 

4.4.3 Flue gas temperature 

For boilers which operate with a flue gas temperature below 160 K and above room temperature at nominal 

heat output, the boiler manufacturer shall make recommendations regarding the flue installation in order to 

ensure sufficient draught and to prevent the chimney sooting up and condensation. 

4.4.4 Draught 

The manufacturer shall specify the minimum draught at the flue gas outlet of the boiler needed for correct 

operation of the boiler. Where the manufacturer gives no detailed values, the figures according to Table B.2 of 

EN 13384-1:2002+A2:2008 shall apply. 

4.4.5 Combustion period 

The combustion period for hand-stoked boilers at nominal heat output shall be stated by the manufacturer and 

shall be at least: 

 2 h for biogenic and other solid fuels ; 

 4 h for fossil fuels. 

4.4.6 Minimum heat output 

For automatically stoked boilers, the minimum heat output shall not exceed 30 % of the nominal heat output. 

This requirement on limiting the maximum heat output shall be achieved automatically by a control device. 

The control of the fuel and/or the air supply may be either continuous or intermittent. 

For manually stoked boilers where the manufacturer specifies that the boiler shall be connected to an 

accumulator tank, the minimum continuous heat output can be greater than 30 % of nominal heat output, 

provided that the manufacturer specifies in the technical documentation how the amount of heat generated is 

to be dissipated. 

Manually stoked boilers do not require testing at minimum heat output if the manufacturer claims that they 

shall always be connected to accumulator tank. 

The following applies as a reference for the minimum accumulator tank volume: 

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













 = × −

min

H

Sp 15 B N 1 0,3

Q

Q V T Q (4) 

where 

Vsp is the accumulator tank volume, in litres; 

QN is the nominal heat output, in kilowatts; 

TB is the burning period, in hours; 

QH is the heating load of the premises, in kilowatts; 

Qmin is the minimum heat output, in kilowatts. 

For heating boilers using several allowable fuels, the tank size shall be based on the fuel which requires the 

largest accumulator tank. The minimum volume of the accumulator tank shall be 300 l. 

4.4.7 Emission limits 

Combustion shall be of low-emission. This requirement shall be satisfied if the emission values shown in 

Table 6 are not exceeded when operating at nominal heat output or, in the case of boilers with heat output 

range, when operating at nominal heat output and minimum heat output, in accordance with 5.7, 5.9 and 5.10. 

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Table 6 — Emission limits 

Stoking Fuel 

Nominal 

heat 

output 

Emission limits

CO OGC Dust 

mg/m3 at 10% O2

a 

kW class class class class class class class class Class

3 4 5 3 4 5 3b 4 5

manual biogenic ≤ 50 5 000 1200 700 150 50 30 150 75 60 

 > 50 ≤ 150 2 500 100 150 

>150 ≤ 500 1 200 100 150 

fossil ≤ 50 5 000 150 125 

> 50 ≤ 150 2 500 100 125 

>150 ≤ 500 1 200 100 125 

automatic biogenic ≤ 50 3 000 1000 500 100 30 20 150 60 40 

> 50 ≤ 150 2 500 80 150 

>150 ≤ 500 1 200 80 150 

fossil ≤ 50 3 000 100 125 

> 50 ≤ 150 2 500 80 125 

>150 ≤ 500 1 200 80 125 

NOTE 1 The dust values in this Table are based on the experience of the gravimetric filter method. The method used needs to 

be referred to in the test report. The particulate matter emission measured according to this European Standard does not include 

condensable organic compounds which may form additional particulate matter when the flue gas is mixed with ambient air. The 

values are therefore not directly comparable with values measured by dilution tunnel methods. Neither can they be directly 

translated into ambient air particulate concentrations. 

NOTE 2 Additional test methods and emission limits which apply in some countries are given in the A-Deviations in Annex C.

a

 Referred to dry exit flue gas, 0 °C, 1013 mbar. 

b

 Boilers of class 3 for type E-fuels according to 1.2.1 or e-fuels according to 1.2.3 in this Table and marked with the classification Efuels and e-fuels do not need to fulfil the requirements for the dust emissions. The actual value shall be stated in the technical 

documentation and shall not exceed 200 mg/m3

 at 10 % O2.

5 Test 

5.1 Test conditions 

5.1.1 General 

The test shall be conducted by a third party meeting the EN ISO/IEC 17025 requirements for testing to this 

European Standard. 

NOTE 1 Organisations or test laboratories holding EN ISO/IEC 17025 accreditation for the testing of solid fuel boilers 

to this European Standard should be used for undertaking the type testing. 

Prior to CE-marking, boilers shall be subjected to the rating test, design test, combustion test, safety test and 

electrical tests. 

The manufacturer shall ensure that the materials used in construction and welds are in conformity with the 

requirements of the Quality Control System, and that the results of all necessary tests conform to those 

requirements. 

All boilers and their parts shall be subjected to a hydraulic or pneumatic pressure test in the works of the 

manufacturer. No leakage shall occur. 

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39 

NOTE 2 All appropriate safety precautions should be taken into account. 

All tests, except for those described in 5.4.2 and 5.5.2, shall be undertaken as part of the type testing of the 

boiler. 

5.1.2 Choice of boiler and fittings to be tested 

Fittings and accessories supplied by the manufacturer shall be installed and used correctly. The operating and 

installation instructions shall be referred to and be taken into account during testing. 

5.1.3 Condition of the boiler 

The condition and the equipment of the boiler to be tested shall conform to the normal supply specification. 

The use of additional thermal insulation to parts in contact with water, products of combustion and fire shall 

not be permitted. 

When determining the thermal output of a boiler fitted with a water heater (either storage or instantaneous), no 

domestic hot water shall be drawn off during the test. The thermal output shall be determined from the heating 

circuit only. 

5.1.4 Type test 

The type test shall determine whether the individual boiler sizes of a type or range meet the requirements laid 

down in this standard. During the type test, the boiler shall be representative of production in its design and 

equipment. 

For boilers which consist of a boiler body which has been previously tested against and meets the 

requirements of this standard and a burner which has already been tested against and meets the 

requirements of EN 15270, only the following tests shall be performed: the tests specified in sub-clauses 5.6, 

5.7, 5.8, 5.9, 5.10, 5.12, 5.13, 5.14 and 5.15. 

For boilers in a product range which have the same constructional design, the testing of only the smallest and 

the largest boiler shall be sufficient, provided the ratio of the nominal heat output of the smallest to largest 

boiler is less than or equal to 2 : 1. If, however, within the same product range, this ratio is larger than 2 : 1, 

then so many intermediate sizes shall be tested so that the ratio of 2 : 1 from the higher performance size to 

the lower performance size is not exceeded. 

The boiler manufacturer shall ensure that all boilers of a product range, even those which have not been 

tested, conform to the requirements of this standard. The results of non-tested boilers shall be determined by 

interpolation based on the nominal heat output. The test rigs shall conform to the general requirements of 

EN 304. 

5.2 Measuring instruments and methods 

The tolerances for test equipment given in A.1 and A.2 of EN 304:1992+A1:1998+A2:2003 shall be taken into 

account. In addition, the measuring instruments shall be selected in such a way that the error limits do not 

exceed the following: 

 for efficiency: ± 3 % points; 

 CO: ± 10 % of the measured value or ± 10 ppm (whichever is greater); 

 THC: ± 10 % of the measured value or ± 5 ppm (reference gas: Propane or Methane) (whichever is 

greater); 

 NOx: ± 5 % of the measured value or ± 15 ppm (whichever is greater); 

 O2: ± 5 % of the measured value or ± 0,4 % volume (whichever is greater); 

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 CO2: ± 5 % of the measured value or ± 0,4 % volume (whichever is greater); 

 dust: ± 10 mg/m3 of the measured value. 

The uncertainty shall be calculated with a 95 % confidence interval. 

Measurements of THC and NOx can be taken with reference to CEN/TS 15883. 

NOTE The measuring instruments for the determination of gaseous emissions should be in accordance with 

EN 12619, EN 13526, EN 14789, EN 14792 and EN 15058. 

The calculation of the OGC emissions shall be performed according to CEN/TS 15883. 

The dust content shall be determined using a filter method according to CEN/TS 15883 and EN 13284-1 in 

combination with Annex A of this standard, or using a gravimetric or electrostatic method according to 

Annex C. Other national methods or practices meeting the error limits requirements given above may be used. 

In order to minimize the errors of measurement, the instruments shall be installed in a zone of as constant a 

temperature as is possible and shall be in operation some time before the commencement of the tests (see 

A.5 of EN 304:1992+A1:1998+A2:2003). 

5.3 Test fuel 

Fuel of commercial quality is used for testing heating boilers and characteristics of the type of fuel as declared 

by the manufacturer according to Table 7. For the purposes of wood test fuels, either beech, birch, oak, 

spruce or hornbeam can be used as declared by the manufacturer. Sampling shall be carried out according to 

EN 14778. 

Testing with chipped wood B2 replaces testing with chipped wood B1. For fuels of class E, the analysis of the 

parameters listed in Table 7 shall be stated in the test report and the fuel shall be classified according to 

EN 14961 (all parts). 

NOTE For the installation and operation of boilers using fuels of class "E, e" national regulations might give rules in 

which test fuels cover commercial fuels, as available in the relevant country. Criteria might also be different regarding 

calorific value, moisture content, ash content, bulk density and elemental content. 

A distinction is made between the following test fuels (Table 7) and the fuels listed in the scope: 

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Table 7 — Test fuels 

Bituminous 

coal 

Brown coal 

(incl. briquettes) Coke Anthracite Wood logs Chipped wood Compress

wood 

a1 a2 b1 

b2 c1 c2 

d A B1 B2 C 

Water content (as received) ≤ 11 % ≤ 20 % ≤ 5 % ≤ 5 % 

12 % 

to 

20 % 

20 % 

to 

30 % 

40 % 

to 

50 % 

≤ 12 % 

Ash contenta

(as received) 2 % to 7 % 5 % to 20 % 5 % to 15 % 5 % ± 3 % ≤ 1 % ≤ 1,5 % ≤ 0,5 % 

Volatilesa

(as received) 

15 % 

to 

30 % 

> 30 % 

40 % 

to 

50 % 

50 %

to 

60 % 

< 6 %

8 % 

± 

2 % 

< 10 % - - - - 

Chlorine contenta

- - - - - - - - 

Sulphur contenta - - - - - - - - N-contenta - - - - - - - - 

Net calorific valueb > 28 MJ/kg > 12,5 MJ/kg > 28 MJ/kg > 28 MJ/kg > 17 MJ/kg > 17 MJ/kg > 17 MJ/k

Size/length According to the manufacturer’s instructionc 

a % of mass on dry base. b Dry base. c Maximum 5 % of mass of the test fuel may have an oversize or an undersize. 

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42 

( )

100

iwf 100 2,442

iw

H w w H − − = (5) 

where 

Hiw is the net calorific value of the wet fuel, in MJ/kg; 

Hiwf is the net calorific value of the fuel on a dry base, in MJ/kg; 

w is the water content as proportion of total mass, in %; 

2,442 is the evaporation heat of water in MJ/kg, referred to 25 °C. 

The water content and the calorific value of the fuel shall be analysed. 

NOTE If accepted by the manufacturer, moisture contents between two classes can be used. The test results are 

valid for the class with the lower water content. 

5.4 Pressure test for boilers of sheet or sheet metal of non-ferrous metal 

5.4.1 Tests to be carried out before production 

The type test pressure is 2 × PS using hydraulic pressure where PS is the maximum permissible operating 

pressure. The test period shall be at least 10 min and if it is to apply to a range of boilers, the test shall be 

carried out on at least 3 boiler sizes (smallest, medium, and largest size). No leakage or noticeable permanent 

deformation shall occur during the test. 

A record shall be made of the test, including the following details: 

 exact description of the boiler tested by stating the drawing number; 

 test pressure in bar and duration of the test; 

 test result; 

 place and date of the test, including the names of persons carrying out the test. 

The test report shall be signed by, as a minimum, the works tester responsible and one witness. 

5.4.2 Test during production 

Each boiler shall be tested during the production and the test pressure shall be at least 1,43 × PS. 

5.5 Pressure test for boilers of cast iron or non-ferrous metals 

5.5.1 Test to be carried out before production 

5.5.1.1 Burst test on individual sections 

To assess the construction and to approve the design, three front, middle and back sections of each boiler 

type shall be subjected to a hydraulic burst test before the start of full production. For boilers with a maximum 

operating pressure up to 6 bar, the minimum burst pressure shall be > 4 x PS + 2 bar (minimum 8 bar). 

The result shall be recorded in a report which gives the following details: 

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 test date and name of tester; 

 model, type and number of sections; 

 model number of the individual sections or other proof of identity; 

 cast date; 

 burst pressure achieved, in bar; 

 description and position of the damage which occurred. 

5.5.1.2 Water pressure tests on boiler block 

For each boiler type which is intended for mass production, the following tests apply: 

 one boiler block of average size shall be subjected to a water pressure test with a pressure of 2 × PS, 

(minimum 8 bar); 

 the strength of the tie bars shall be calculated and tested to withstand an internal boiler pressure of 4 × PS. 

A record shall be drawn up of the result. See 5.4.1 for details. 

5.5.2 Test during production 

5.5.2.1 Cast sections 

Each boiler section shall be subjected to a cold water pressure test with a pressure of 2 X PS (minimum 8 

bar). The highest permissible test pressure is 10 bar. 

The wall thickness at the individual boiler sections shall be subjected to an examination during production in 

accordance with a quality control. 

The limiting value of wall thickness at each measuring point shall be the wall thickness less the permissible 

tolerance. 

Boiler sections and parts which are subjected to pressure shall have the following information cast onto them: 

 manufacturer or manufacturer's symbol; 

 details of the material; 

 cast date; 

 model number; 

 mark of conformity, if granted. 

5.5.2.2 Boiler block 

Each boiler is to be subjected to a water pressure test with a test pressure of 1,3 x PS (minimum 4 bar) before 

fitting the thermal insulation at the manufacturer's works. For boilers which are site assembled by the installer, 

the boiler manufacturer shall provide instructions to carry out the pressure test. No leakage shall occur during 

the water test. 

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5.6 Test for gas side soundness 

This test is for boilers with a positive pressure in the combustion chamber. 

The specified limit values for permissible leakage rates are determined with the mass of the gases equivalent 

to the rated output. 

The actual leakage rate of the boiler is determined using air at ambient temperature and using a test rig in 

accordance with (for example) Figure 2. 

Exhaust connection is to be sealed tightly, and the doors set as in normal use. The test rig is connected to the 

air input of the test boiler. 

The leakage rates measured are to be converted in accordance with the standard test condition (0 °C, 1013 

mbar). The requirements of 4.3.7 shall be reached. 

Key

1 pressure measuring point 4 flow meter 7 valve 3 (bypass) 

2 flue gas outlet 5 valve 2 8 firing air inlet 

3 valve 1 (regulating) 6 fan 9 boiler 

 10 pressure measuring point 

Figure 2 — Measuring point for determination of the gas-side soundness 

NOTE The test for boilers operating with negative pressure can be performed under a pressure of 20 Pa (see 

Figure 2, measuring point 10). The test should be performed after safety and performance test (5.7 to 5.15) 

5.7 Conducting the boiler performance test 

5.7.1 General 

To determine the heat output, boiler efficiency, combustion period, composition of the combustion gas, exit 

flue temperature, draught and emission properties, the boiler is operated throughout the tests within the heat 

output range. At nominal heat output, the boiler shall be operated in such a way that continuous running is 

possible (with thermostat cut-off prevented). The minimum heat output on boilers shall be regulated 

automatically by a control device without a manual intervention. The boiler shall be brought to operating 

temperature before the start of any measurements.

The appliance shall be operated in accordance with the manufacturer's operating instructions during the tests. 

The ambient air temperature shall be between 15 °C and 30 °C. 

The draught is to be set according to the minimum draught of the manufacturer's instructions. 

In the test period, the mean value of the draught shall not vary from the specified value of the manufacturer by 

more than ± 3,0 Pa. 

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During the test period, manual intervention in the form of poking or raking or any adjustment shall not be 

permitted. 

If approximately 95 % of expected combustion period has elapsed for hand stoked boilers, brief raking is 

allowed before the datum fire bed is created This serves to distribute unburned fuel prior to the refill operation 

and is not to be considered as a manual intervention during the combustion period; it is therefore permissible 

in every valid test. 

The test procedure according 5.8 and 5.9 shall be performed at the same time. 

5.7.2 Setting up the test rig 

The test rig shall be set up as shown in A.6 of EN 304:1992+A1:1998+A2:2003 and the efficiency shall be 

determined within a tolerance of ± 3 % points. 

Other equivalent arrangements of rigs may be used. 

The flue gas measuring section shall be carried out in accordance with Figure 3 of 

EN 304:1992+A1:1998+A2:2003. 

5.7.3 Measured quantities 

The following one-off measurement parameters shall be undertaken and recorded in the type test report: 

 water content of the fuel; 

 net calorific value of the fuel; 

 fuel mass added; 

 combustion period during hand stoking; 

 surface temperatures (at nominal heat output in a typical operating condition). 

The following measured quantities shall be continuously measured and recorded in the type test report: 

 heat output; 

 flow temperature; 

 return temperature; 

 temperature of the entering cold water according to Figure A.2 of EN 304:1992+A1:1998+A2:2003; 

 ambient temperature; 

 flue gas temperature; 

 draught; 

 oxygen (O2) or carbon dioxide (CO2) content; 

 carbon monoxide (CO) content; 

 organic gaseous substances THC (total hydro carbon); 

 dust content (intermittent measurement); 

 auxiliary energy demand. 

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NOTE The state of the art is such that limit values for nitrogen oxides cannot be stated. It is recommended to 

measure NOx-values. In addition, the nitrogen should be determined of the test fuel: NO and NO2 are measured and the 

result is shown as NO2. 

All the measured quantities to be determined continuously are at maximum intervals of 20 s and recorded as 

mean values at maximum intervals of 1 min. The time intervals are to be chosen in such a way that 

fluctuations in the measured values are recorded with sufficient accuracy. 

The recorded mean values are the basis for making the mean value for the test period. 

5.7.4 Test method and test duration 

5.7.4.1 Heating boilers with manual stoking 

Before the start of the test, the boiler shall be brought to its stable working condition. The duration of this initial 

period shall be at minimum 2 h and sufficient to ensure the necessary basic fire bed is established. The 

necessary basic fire bed shall be described prior to testing by the manufacturer and shall be stated in the 

technical documentation. This shall be described in the test report, e.g. by the duration of the combustion 

period. 

The test period shall begin when the basic fire bed is either judged visually to be achieved or, if using a 

platform scale, when the mass of basic fire bed is indicated on the scale. Other indicators like the CO2 content 

or the flue gas temperature shall be also taken into account when judging the basic fire bed. 

The test shall start immediately after placing a complete fuel charge up to the maximum filling height on the 

basic fire bed. The test time runs from the time when the fuel is placed on the basic fire bed until the next refill. 

The refill and the stoking are included in the test time and calculation of the mean value. 

 Test duration at nominal heat output: 2 consecutive combustion periods; 

 Test duration at minimum heat output: 1 combustion period. 

Both combustion periods at nominal heat output shall show similar test results (i.e. heat output ± 10 % of the 

mean value). 

5.7.4.2 Heating boilers with automatic stoking 

Before the start of the test, the boiler shall be brought to operating temperature using the appropriate quantity 

of fuel; the necessary stable operating conditions are established. The following specifications apply: 

 test duration at nominal heat output shall be at least 6 h; 

 test duration at minimum continuous heat output shall be at least 6 h; 

 test duration at minimum heat output in intermittent operation shall be at least 6 h plus the time taken to 

finish the last on-off period. 

For automatically fed wood log boilers, the test conditions shall be applied according to boilers with automatic 

stoking devices for pellets and chipped wood. 

For automatically fed wood log boilers, the testing period shall include at least two stoking intervals. 

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5.8 Determination of the heat output and the efficiency of the boiler 

5.8.1 Method for the measurement of the heat output 

5.8.1.1 General 

The amount of useful heat transmitted to the heat carrier (water) is measured. It can be determined directly in 

the boiler circuit or indirectly by means of a heat exchanger. 

When hand stoked boilers are tested with a heat output greater than 30 % of nominal heat output, the test rig 

shall be controlled in accordance with the boiler heat output produced. 

5.8.1.2 Determination of heat output in the boiler circuit 

The useful heat output transmitted to the water is determined either by measuring the mass flow of cold water 

entering the boiler circuit and the rise of temperature to the outlet temperature, or by measuring the flow of the 

water circulating in the boiler circuit and its temperature rise. 

5.8.1.3 Determination of heat output by means of a heat exchanger 

The heat produced by the boiler is transferred to the cooling water by means of a heat exchanger. The heat 

received by the latter is calculated from the throughput and the temperature rise of the cooling water. The heat 

losses from the well-insulated connections between the boiler and the heat exchanger and those of the heat 

exchanger itself are determined either by preliminary tests or by test rig specific heat loss curves. 

The heat output of the boiler shall be determined as the sum of the two amounts of heat. 

5.8.2 Determining the nominal heat output 

The heat output specified by the manufacturer shall be determined within ± 8 % during testing. For manually 

stoked boilers, the manufacturer's claimed nominal heat output shall be achieved in at least one of the 

combustion periods. If not, the specified nominal heat output shall be corrected. 

During tests at nominal heat output, the mean value of flow temperature shall be between 70 °C and 90 °C. 

During the test, the mean temperature difference between flow and return shall be between 10 K and 25 K. 

A temperature rise of: 

t K

t t 35,0

2 L

V R − ≥

+ (6) 

shall be maintained, where 

tV is the flow temperature, in °C; 

tR is the return temperature, in °C; 

Lt is the ambient temperature, °C. 

5.8.3 Determining the minimum heat output 

The minimum heat output test is to be conducted at the lowest output specified by the manufacturer, and the 

requirements of 4.4.6 shall be achieved. 

The waterside flow temperatures stated under 5.8.2 shall also be taken into consideration for this test, with the 

exception of the difference between flow and return temperature. 

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The minimum heat output shall be controlled before the start of the test. For this reason, the heat output at the 

test stand shall be reduced. The boiler shall reach the heat output automatically by the control device. 

5.8.4 Determination of the boiler efficiency (direct method) 

The efficiency shall be determined using the direct measurement method on the basis of the net calorific value

Hiw. 

NOTE The indirect method allows an additional check of test accuracy of the test rig to be made by means of a heat 

balance. From this the values of other losses e.g. case losses can also be determined. These losses should not be 

credited to the output or the efficiency of the boiler. 

5.8.5 Electrical consumption 

During the tests, the electrical consumption shall be determined according to EN 15456. 

The values for maximum consumption, for stand by, nominal heat output and minimum heat output shall be 

stated in the test report. For boilers with automatic feeding systems (fuel line), the electrical consumption of 

the boiler and the fuel line shall be determined and stated separately. 

The average electrical power consumption during stand by shall be measured for a minimum duration of 

10 min and shall be stated in watts. In cases where control operations influence the intrinsic energy 

consumption, a longer duration might be necessary. 

5.9 Determination of the emission values 

5.9.1 Heating boiler with manual stoking 

The arithmetic average CO2 or O2, CO, OGC (and NOx where appropriate) contents are determined over the 

entire test period. With manual stoking, the measurement at nominal heat output covers two consecutive 

combustion periods. The refill operation is included in the test results and the mean values. 

At minimum heat output, the measurements are made over one combustion period. 

Each combustion period is divided into, at minimum, two equal time sections. The measurements for 

determining the dust content start in each case at the beginning of a time section, with the first measurement 

beginning immediately after the fuel is placed and the door closed in deviation from CEN/TS 15883. The 

suction time per filter shall be ≥ 30 min. The average dust content is determined from a minimum of four 

measured values. 

5.9.2 Heating boiler with automatic stoking 

The arithmetic average CO2 or O2, CO, OGC (and NOx where appropriate) contents are determined over the 

entire test period at nominal heat output. 

To determine the dust content, each test period is divided into, at minimum, four equal time sections. The 

measurements begin in each case at the start of the sections, with the first measurement taken when the test 

begins. The suction time per filter shall be ≥ 30 min. The average dust content is determined from a minimum 

of 4 measured values. 

At intermittent operation, only complete on-off phases shall be considered. 

5.9.3 Determination of the emissions at minimum heat output 

At minimum heat output the measurements are made over one combustion period. 

The arithmetic average CO2 or O2, CO and OGC contents are determined over the entire test period. 

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NOTE Legislation in some countries requires measurement of NOx and dust at minimum heat output. 

5.10 Calculation 

5.10.1 Boiler heat output 

The boiler heat output is the average during the test period. 

The necessary formulae relevant to the individual test methods are given in A.7 of 

EN 304:1992+A1:1998+A2:2003. 

5.10.2 The heat input 

For these calculations, formulae in A.8.1 of EN 304:1992+A1:1998+A2:2003 shall be used. 

5.10.3 Boiler efficiency 

The boiler efficiency shall be stated in percent in the report. 

5.10.3.1 Direct method 

In the direct method, the boiler efficiency is determined by: 

100

B

K = ×

Q

Q η % (7) 

5.10.3.2 Indirect method (only to be used for checking purposes, see A.9 of 

EN 304:1992+A1:1998+A2:2003) 

In the indirect method, the boiler efficiency is given by: 

η K = (1− qA − qU − qS − qB ) ×100 % (8) 

where 

qA is the loss through sensible heat of the products of combustion (values relative to the heat input); 

qU is the loss through incomplete combustion (values relative to the heat input); 

qS is the loss through radiation, convection and conduction (values relative to the heat input); 

qB is the loss through unburned fuel in ash (values relative to the heat input). 

5.10.4 Emissions 

5.10.4.1 Emissions at nominal heat output and minimum continuous heat output 

The calculation of the mean values shall be performed over the entire testing period only with regard to time, 

independent of the flue gas flow rate. 

The recorded emission values of the volume parts in the dry flue gas shall be used to calculate the mean 

value for the entire testing period. 

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These mean values of the volume parts (ppm) shall be used to calculate the mass values (mg/m3). For the 

rate of exchange from ppm to mg/m3

, the following values should be used: 

 fCO = 1,25; 

 fOGC = 1,64 (if propane is the calibration gas); 

 fOGC = 0,54 (if methane is the calibration gas); 

 NO2 f = 2,05. 

The concentrations of gaseous organically bound carbon (OGC) are reported as carbon. The determined 

oxides of nitrogen (NOx) concentration are reported as nitrogen dioxide (NO2). 

All reported emission concentrations are reported as a mass concentration (mg/m3

) standardised to a dry flue 

gas basis at 10 % oxygen and standard condition (mg/m3

) at 0 °C and 1013 mbar. 

5.10.4.2 Emissions at minimum heat output at intermittent operation 

The calculation of the mean values according to 5.10.4.1 shall be performed over the entire testing period only 

with regard to time, independent of the flue gas flow rate. 

The minimum heat output test shall be conducted at maximum 30 % of nominal heat output. The heat 

consumption of the test rig shall be continuous according to the lowest output specified by the manufacturer. 

5.11 Determination of the waterside resistance 

The water side resistance (measured in mbar) shall be determined for the flow which is equivalent to the rated 

output of the boiler at a temperature difference of ∆t = 10 K and 20 K between the flow and return. 

5.12 Surface temperature 

The mean surface temperature shall be measured at nominal heat output. In order to do this, a minimum of 5 

points on each boiler surface shall be measured. Under the same conditions, the critical temperatures (e.g. 

boiler doors, operating levers) shall be measured. 

5.13 Function check of the temperature controller and safety temperature limiter at the boiler 

The water-side flow rate shall comply with that specified for the nominal heat output test. The flow temperature 

of 75 °C shall not be exceeded at the start of the test. 

Adjust the firing so that it corresponds to the nominal heat output QN of the boiler. A steady state condition 

shall be reached and the outlet pressure at the flue gas section shall be according to the nominal heat output 

setting. For manual stoked boilers, the boiler shall be refuelled after reaching steady state with a full batch 

before starting the test. 

The dissipated output shall be reduced to (40 ± 5) % of the nominal heat output of the boiler; circulating pump 

running in continuous operation; temperature controller adjusted to maximum set value. 

When the temperature controller is operating normally, the measured flow temperature shall not exceed 

100 °C; the safety temperature cut out or limiter or the device for dissipating excess heat shall not trigger. 

Repeat the test with the temperature controller out of function. This time, check if the safety temperature 

limiter/detector switches off the firing system at the highest value specified by the boiler manufacturers and if 

all hazardous operation states are avoided (see 4.1). 

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5.14 Function test for the rapidly disconnectable firing system 

 Sudden absence of heat dissipation 

The water-side flow rate shall comply with that specified for the nominal output test. The flow temperature 

of 75 °C shall not be exceeded at the start of the test. 

Adjust the firing so that it corresponds to the nominal heat output QN of the boiler, a steady state 

condition is reached and the outlet pressure at the flue spigot is according to the rated heat output. 

The heat consumption is set to 0; water circulation in the boiler is permitted; temperature controller is 

adjusted to manufacture recommended maximum set value. 

Check if the safety temperature limiter or the temperature controller switches off the firing system and all 

hazardous operation states are avoided. 

 Loss of the electrical power supply 

The water-side flow rate shall comply with that specified for the nominal heat output test. The flow 

temperature of 75 °C shall not be exceeded at the start of the test. 

Adjust the firing so that it corresponds to the nominal heat output QN of the boiler, a steady state 

condition is reached and the outlet pressure at the flue gas section is according to the rated heat output. 

The electrical supply including the circulation is cut off, check that no hazardous operation conditions 

occur. 

For the evaluation of the temperatures and the CO-concentrations, only mean values at a maximum average 

time of one minute shall be considered. 

5.15 Function test on the device for dissipating excess heat (partly or non-disconnectable 

firing system) 

Adjust the firing so that it corresponds to the nominal heat output QN of the boiler, a steady state condition is 

reached and the outlet pressure at the flue gas section is according to the nominal heat output. 

Put the temperature controller out of function. Maintain the function of the safety temperature limiter. 

The heat consumption is set to 0; water circulation in the boiler is permitted. 

Check if the safety temperature limiter switches off the firing system and the device for dissipating excess heat 

works properly and all hazardous operation states are avoided. 

The cold water shall be kept at a temperature of (10 ± 5) °C and a pressure of maximum 2 bar. (Deviations 

are permissible if they are specified in the installation instructions.) 

For the evaluation of the temperatures and the CO-concentrations, only mean values at a maximum average 

time of one minute shall be considered. 

5.16 Check of the safety and risk assessment 

5.16.1 General 

A risk analysis shall be performed by the manufacturer according to EN ISO 12100. "Force majeure risks" 

shall not be taken into consideration. 

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Completeness, correctness and plausibility of the risk analysis of the manufacturer shall be verified by a third 

party. 

The verification does not generally require testing. If tests are performed, the following conditions shall be 

applied. 

a) Adjust the firing so that it corresponds to the nominal heat output QN of the boiler, a steady state condition 

shall be reached and the outlet pressure at the flue gas section shall be according to the nominal heat 

output setting. 

b) For manual stoked boilers, the boiler shall be refuelled after reaching steady state with a full batch before 

starting the test. 

The verification of the risk analysis can be done on the basis of one or more of the following: 

 implementation of accepted solutions according to this standard; 

 implementation of safety functions with verification of the shut-off function; 

 check of the characteristics of the boiler at normal operation and in the case of failures; 

 relevant references to other standards or associated test results. 

The risk analysis shall at least provide risk assessments for the following tasks and take into account possible 

failures in the components of the fuel supply, the air supply, the combustion and combustion control, the flue 

gas exit, the heat dissipation, fire prevention and the risk of injuries of persons. 

The following risks shall be evaluated in detail: 

c) fuel feed operation continuously at maximum speed, fuel overload; 

d) feed rate too low; 

e) loss of air supply; 

f) loss of power; 

g) unstable combustion chamber pressure; 

h) unclosed doors and openings within the boiler or the stoking device; 

i) open integral fuel hopper; 

j) empty integral fuel hopper; 

k) ignition failure during start up; 

l) check of the strategy for safety against back burning; 

m) safety check regarding effect of emptiness or a blockage of the stoking device; 

n) voltage variation; 

o) leakage of combustion products (e.g. flue gas fan failure, power loss, pressurized combustion chamber); 

p) lockout and restart; 

q) electric safety (documents and certificates have to be provided); 

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53 

r) risk of injuries of persons. 

NOTE Additional tests are recommended. 

5.16.2 Safety test of consequences of fuel overload and effect of a blockage of the fuel supply 

The safety of the boiler shall be checked at continuous operation of the boiler with the fuel feed rate of the 

stoking device set at possible maximum capacity, taking into account failures according to the risk analyses 

and the electrical safety. If other fuel feed rates lower than the maximum are categorised as critical by the risk 

analysis, these shall also be tested. 

The functionality of the safety device for the shut-down of the fuel line shall occur by prevention of the ignition 

after release of fuel if no or insufficient combustion in the combustion chamber occurs. 

The test for blocked fuel line shall be achieved by deactivating the stoking device. 

The requirements specified in 4.3.4 shall be satisfied. 

5.16.3 Loss of combustion air supply 

The safety of the heating boiler shall be checked at maximum heat input under the following conditions: 

 failure of the combustion air fan; 

 failure to close of the adjustable combustion air supply. 

In each case, only one failure shall be simulated. 

The CO concentrations in the boiler shall not exceed 5 % volume. 

The measurement of CO concentration shall be carried out in the flue gas measuring section. 

5.16.4 Resistance to thermal conductance 

Temperature measurement shall be performed on the surface of the stoking device at the place next to the 

fuel line but within a maximum distance which shall be less than 1 m against the feeding direction from the 

inner wall of the combustion chamber. 

For boilers with integrated hopper, the temperature measurement shall be performed on the surface of the 

stoking device at the place next to the integrated hopper but within a maximum distance which shall be less 

than 1 m against the feeding direction from the inner wall of the combustion chamber. In addition, the highest 

surface temperature of the hopper shall be measured. 

5.16.5 Additional tests for alternative verification of the safety against back burning 

This test shall be performed only if the criteria in 4.3.3.5 are applied. The tests shall be carried out with 

reference to the risks listed in 5.16.1. 

These tests shall include at least the verification of the geometrical, physical, mechanical and electrical 

properties that are required for this device by applying the risk assessment performed. The device shall be 

tested in respect of the interaction of the device in the functional safety concept and the control algorithms of 

the boiler. 

A test for the simulation of a back burning shall at least fulfil the following criteria: 

a) using the original boiler or test samples which simulate the firing system and the fuel line of the boiler on 

one hand and which allow the performance of back burning tests on the other hand; 

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b) by generating hot gases in the original combustion chamber or using devices to produce hot gases like a 

forced draught burner at the fuel entrance into the combustion chamber; 

c) by producing a pressure drop from the combustion chamber to the fuel line, representing the most critical 

situation due to the risk assessment. The pressure drop shall be at least 8 Pa. 

The test shall be documented in a report including the description of the test sample and the test installation, 

the way to perform the back burning test, the test conditions and the test results. 

6 Test report and other documents 

Test reporting shall be issued on the basis of EN ISO/IEC 17025 requirements. 

The test report shall include at least: 

a) name and address of the test laboratory and the location were the tests have been carried out; 

b) identification number of test report; 

c) name and address of customer; 

d) test method; 

e) description of the boiler or the series of boilers which are tested including: 

1) general construction; 

2) supply of fuel; 

3) supply of combustion air; 

4) safety devices with identification (type, certification, supplier, adjustment, size); 

5) relevant components (fan, ignition device, inserts in heat exchangers); 

f) parts list (where appropriate); 

g) period of testing; 

h) test results as mean value of the test period and for manually stoked boilers of each combustion period; 

i) specification of the test method used for particles measurement 

j) picture of the boiler. 

The following documents shall be handed over to the test institute: 

 drawings showing clearly the type of construction of the boiler (or boiler series); 

 drawings showing clearly the material, welding (where appropriate) and wall thickness of pressurized 

parts; 

 installation and operating manual as well as other relevant documents of the manufacturer; 

 a description of the boiler including the draft of the boiler data plate. 

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The test report shall be signed by the head of the test station or the test engineer responsible for carrying out 

the test. 

The test report shall not be published in abbreviated form. 

7 Marking 

7.1 General 

Each heating boiler shall have a data plate. The boiler data plate shall be written in the language of the 

country of destination and be affixed in an accessible spot. 

7.2 Information on the boiler plate 

The boiler plate shall contain at least the following information: 

a) name and company domicile of the manufacturer and, where available, the manufacturer's symbol; 

b) trade designation, type under which the boiler is marketed; 

c) production number and year of construction (coding is permissible at the manufacturer’s discretion); 

d) nominal heat output and heat output range in kilowatts for each type of fuel; 

e) boiler class regarding each fuel type that was tested; 

f) maximum allowable operating pressure, in bar; 

g) maximum allowable operating temperature, in degrees Celsius; 

h) water content, in Iitres; 

i) electrical connection (V, Hz, A) and wattage, in watts; 

j) the fuel class according to Clause 1 and for fuels of class E the tested fuel. 

7.3 Boiler plate requirements 

The material and labelling used for the plate shall be durable. The labelling shall be abrasion-proof. Under 

normal operating conditions the plate shall not discolour so as to make its information difficult to read. Selfadhesive plates should not become detached as a result of moisture and temperature. 

8 Technical documentation, supplied with boiler 

8.1 General 

For each boiler, the documents listed below shall be made available in the language of the boiler's country of 

destination; the documents specified under 8.2 and 8.3 shall be enclosed with every boiler. 

8.2 Technical information and installation instructions 

These documents shall contain at least the following indications: 

a) necessary draught, in millibars; 

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56 

b) water content, in litres; 

c) exhaust gas temperature at nominal heat output and minimum heat output, in degrees Celsius; 

d) exhaust mass flow at nominal heat output and at minimum heat output, in kilograms per second; 

e) flue pipe diameter, in millimetres; 

f) water-side resistance, in millibars; 

g) nominal heat output and heat output range, in kilowatts; 

h) boiler class; 

i) combustion period in hours at QN ; 

j) setting range for the temperature controller, in degrees Celsius; 

k) minimal return temperature at boiler return tapping, in degrees Celsius; 

l) fuel type and water content as well as fuel size and detail information according to Table 7 for fuels type E 

resp. e; 

m) filling chamber capacity in litres and filling opening dimensions, in millimetres; 

n) necessary accumulator storage, in litres if Qmin > 0,3 QN ; 

o) auxiliary power requirement at QN and Qmin, in watts; 

p) stand by power, in watts; 

q) cold water temperature and pressure for safety heat exchanger, in bars; 

r) electrical connections including appliance and main-switch-off; 

s) whether the heating appliance is running with or without using a fan; 

t) whether the heating appliance is working under over pressure or under pressure at flue gas outlet; 

u) whether the heating appliance is working under condensing or non-condensing conditions; 

v) information about the boiler's emission of airborne noise, the method to measure the airborne noise level 

and the possibilities of means of reducing the noise emission of the boiler. 

NOTE Noise measurements should be made according to EN 15036-1. 

Furthermore, the installation instructions shall contain information concerning: 

w) the on-site assembly of the boiler (if necessary) and the required water pressure test as per 5.4.2 or 

5.5.2.2; 

x) the installation; 

y) the commissioning, with information on the boiler output to be set in the output range; 

z) instructions on the location and fitting of the sensors for the control, display and safety equipment. 

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In addition, the technical information and installation instructions shall contain general references to the 

standards and regulations to be observed on the safety equipment of the installation: 

 take care of installed ventilations systems in the same heating room; 

 take care there is sufficient amount of clean (i.e. uncontaminated) combustion air; 

 measuring points should be self locking and thigh; 

 emission control after first installation; 

 verbal instruction by a competent person before first using; 

 take care of the correct storage of the used fuels; 

 regularly checks if the heating appliance is in good condition; 

 take care of the correct dimensioning of the System; 

 take care of the correct dimensioning of the chimney including the connecting flue pipe; 

 take care of the necessary distances to combustible materials, if required; 

 require a shielding construction, if necessary; 

 take care of the necessary minimum distance to walls and ceilings (related to cleaning). 

8.3 Operating instructions 

The operating instructions shall contain references to: 

 the operation of the boiler, stoking and opening doors without risk; 

 cleaning and cleaning intervals, including the equipment required for the cleaning operations; 

 measures to be taken in the event of malfunction; 

 the reasons for recommending a regular, competent maintenance service and the necessary 

maintenance intervals; 

 the type of fuel and water content and the fuel size (with the direction of the layers in the case of wood 

logs); 

 the maximum filling height for fuel in the filling chamber; 

 the nominal combustion period for fuel types at nominal heat output. 

Other documents (brochures, etc.) shall not contain any information that is in contradiction with that of the 

operating instructions. 

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58 

Annex A

(informative) 

Manual measurement of particles in the gas flow, gravimetric 

determination of particle load with filter systems 

This informative annex describes the procedure for the determination of particle emissions on the test item. It 

provides the basic requirements for testing. 

Before and after the sampling, the used filter shall be dried in a drying oven until a constant mass is reached 

(drying temperature at least (110 ± 5) °C). After the drying of the filters and prior to the weighing process, the 

filters shall be stored in a desiccator. The desiccator shall be placed in the room where the weighing takes 

place until the temperature of the desiccator reaches ± 3 K of the temperature of the room. 

To provide traceability regarding the pre-treatment of the weighed sample parts, the following results shall be 

stated in the test report: 

 drying temperature of filter prior to and following impingement; 

 minimum drying period of filter prior to and following impingement. 

The sample equipment (Figure A.1) shall be mechanically cleaned and rinsed prior to each test series. 

Because of the low flue gas velocities of domestic heating appliances (< 2 m/s), the extraction velocity at the 

filter head shall remain in the interval of 70 % to 150 % (as a deviation to EN 13284-1 in which an isokinetic 

sampling rate in the interval of 95 % to 115 % is stated). It is assumed that the basics of the process are 

fulfilled if during sample time the isokinetic sampling rate does not exceed a value of 150 %. 

The configuration of the extraction unit shall be done corresponding to EN 13284-1. In case of out-stack 

sampling, the extraction probe of the out-stack unit shall be kept as short as possible and the filter head shall 

be heated at the temperature of the measured flue gas or at (110 ± 5) °C. 

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59 

Key 

1 

2 

3 

4 

5 

6 

7 

8 

filter 

gas sampling probe and line for 

particles measurement (heatinsulated) 

water separator 

silica gel filter 

superfine filter 

pump 

gas flow meter 

insulation t = 40 mm 

section for draught measuring 

I 

II

III 

section for draught 

measuring 

section for 

temperature 

measuring 

measuring device for 

flue gas analysis 

(sampling cross) 

section for measuring the smoke 

contents in the flue gas 

immersion depth of the thermocouples: 

E1 = 0,10 · D

E 2 = 0,17 · D

E 3 = 0,24 · D

E 4 = 0,30 · D

E 5 = 0,37 · D

Figure A.1 — Scheme of the sampling equipment

Key 

1 

2 

3 

removable sampling probe 

union nut 

seal 

4 

5 

6 

filtering bush 

quartz wool 

filter housing 

7 

8 

9 

union nut 

clamping ring 

flat filter support 

10 

11 

flat filter 

end case 

Figure A.2 — Example of a tubular filter device 

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60 

Key 

1 

2 

3 

4 

5 

pipe wall 

stainless steel tubing 

(inner ø 9) 

sampling probe 

heater band 

0-ring seals 

6 

7 

8 

threaded coupling 

filter ø 47 

thermocouple pocket 

9 ø 44 X 1.5 thick 

perforated support disc 

with 109 X ø 2.2 equispaced holes on 

triangular pitch 

10 

11 

12 

ø 47 X 0.4 thick perforated 

filter support disc with ø 0.55 

equi-spaced holes on 

triangular pitch 

Insulation 

M12 threaded end for nozzle 

attachment 

NOTE The sample nozzle, probe and filter housing material is stainless steel. 

Figure A.3 — Suggested arrangement − Filter housing 

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Annex B 

(normative) 

Design criteria for solutions to prevent back burning 

Table B.1 — Design criteria for solutions to prevent back burning 

number 

Prevention of thermal 

conductance 

Prevention of back 

flow 

Prevention of fire 

propagation 

Independent on power 

supply Accepted Solution Detailed criteria to fulf

acce

 4.3.3.2 4.3.3.3 4.3.3.4 4.3.3.1 according to 

1 YES NO YES YES Extinguishing device using the medium water The extinguishing de

distribution of the w

the amount of available 

nominal hea

if the amount of water is 

the stoking device, a pe

supply 

the extinguishing device 

STB according to EN 1

function) 

water is not acce

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62 

Table B.1 (continued)

number 

Prevention of thermal 

conductance 

Prevention of back 

flow 

Prevention of fire 

propagation 

Independent on power 

supply Accepted Solution Detailed criteria to fulf

acce

4.3.3.2 4.3.3.3 4.3.3.4 4.3.3.1 according to 

2 YES NO YES NO Emergency discharge device operating 

automatically. 

Automatic discharge activa

(STW + non volatile locko

°C or an increase of 

∆t = 2

(maximum 95 °C) emptyi

fillin

3 YES NO NO NO A stoking device which is cooled by a water circuit 

and the temperature of the water is limited by a 

cut out (e.g. water circuit is part of boiler circuit). 

Maximum water tempe

separate STB or the ST

4 YES NO YES YES An extinguishing device directly in the hopper e.g. 

water sprinkler system and a STB adjusted to a 

maximum of 95 °C. 

The extinguishing dev

distribution of the wa

a permanent connecti

the extinguishing device sh

according to EN 14597 (S

react

5 YES NO NO YES Sufficient insulation of the hopper from hot parts 

of the boiler. 

Insulation shall be ma

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Table B.1 (continued)

number 

Prevention of thermal 

conductance 

Prevention of back 

flow 

Prevention of fire 

propagation 

Independent on power 

supply Accepted Solution Detailed criteria to fulfi

acce

4.3.3.2 4.3.3.3 4.3.3.4 4.3.3.1 according to 

6 YES NO NO YES Naturally ventilated space between hopper and 

boiler body (separate casing). 

Requirement shall be fu

5.16.4 withou

7 NO YES YES YES Safety device to maintain a continuous seal 

between the stoking device and the fuel line. 

Safety device continuously 

the nominal flue gas flow 

ambient temperature and a 

permissible positive press

th

a free cross section and 

device without any disturb

shut d

8 NO YES YES YES Safety device to maintain a seal between the 

stoking device and the fuel line not during the 

supply of fuel, but during all other states of 

operation. 

Safety device (not continu

1 % of the nominal flue ga

at ambient temperature an

state 

only allowed for boilers de

pressure in the 

sufficient space to opera

disturbance of fuel (norma

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EN 303-5:2012 (E) 

64 

Table B.1 (continued)

number 

Prevention of thermal 

conductance 

Prevention of back 

flow 

Prevention of fire 

propagation 

Independent on power 

supply Accepted Solution Detailed criteria to fulfi

acce

4.3.3.2 4.3.3.3 4.3.3.4 4.3.3.1 according to 

9 NO YES YES YES Tight fuel hopper lid in combination with pressure 

equalization and interlock switch. 

Tight fuel hopper lid in comthat works during normal oshut down or power loss. Dhopper shall be avoided by equalization between the chopper. The dimension of tsufficient to equalize presspropagation. Hopper lid sha(according to H27 of EN 60air supply in case of an opeshall be reached without massistance). 

10 

NO YES YES YES Tight fuel hopper lid in combination with negative 

pressure operation of the boiler, inclined auger 

and an interlock switch. 

Tight fuel hopper lid in comoperation of the boiler. Diffushall be avoided by natural Hopper lid shall be fitted wiH27 of EN 60730-2-5) whiccase of an open lid. Minimudifference 20 cm. 

11 NO YES YES YES Use of directed flow to create stable pressure 

conditions. 

Use of directed flow to creainjector, safety device class rotation of supply fan or relfuel supply in case of failurbe achieved by a inclined aconditions as described in 

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Table B.1 (continued)

Number 

Prevention of thermal 

conductance 

Prevention of back 

flow 

Prevention of fire 

propagation 

Independent on power 

supply Accepted Solution Detailed criteria to fulfi

acce

4.3.3.2 4.3.3.3 4.3.3.4 4.3.3.1 according to 

12 NO YES YES YES Inclined auger in combination with a fuel transport 

slide into the combustion chamber. 

Only for boilers 

≤ 70 kW 

Inclination minimum 30° Minimum height fuel transp150 mm 

≤ 15 kW 

250 mm > 15 kW 

≤ 70 kW 

13 NO NO YES YES Drop chute without any safety device and 

minimum height. 

Only for pellet boilers up to minimum height 150 mm 

≤ 15 kW 

250 mm > 15 kW 

≤ 70 kW 

300 mm >70 kW 

≤ 300 kW 

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66 

Annex C

(informative) 

A-deviations

C.1 General 

A-deviation: National deviation due to regulations, the alteration of which is for the time being outside the 

competence of the CEN/CENELEC national member. 

This European Standard falls under Directive 2006/42/EC Machinery Directive. 

NOTE Where standards fall under EU Directives, it is the view of the Commission of the European Union (OJ No C 

59, 1982-03-09) that the effect of the decision of the Court of Justice in case 815/79 Cremonini/Vrankovich (European 

Court Reports 1980, p. 3583) is that compliance with A-deviations is no longer mandatory and that the free movement of 

products complying with such a standard should not be restricted except under the safeguard procedure provided for in 

the relevant Directive. 

[SOURCE: CEN/CENELEC IR Part 2:2002, 2.17] 

A-deviations in an EFTA-country are valid instead of the relevant provisions of the European Standard in that 

country until they have been removed. 

C.2 Deviations from Austria: 

C.2.1 General 

Subclause 4.4.2 

Figure 1: Boiler efficiency 

Subclause 4.4.7 

Table 6: Emission limits 

EN 303-5 disagrees with the Austrian law (agreement according to Art 15a B-VG relating the placement of 

small burners on the market and the testing of firing systems and combined heating and power stations, 

October 2009). Small burners may only be put into circulation if the requirements of the following agreement 

are fulfilled. 

Austria has stricter limits relating to boiler efficiency and emissions. For this reason, the following A-deviation 

is necessary: 

C.2.2 Boiler efficiency for nominal heat output and minimum heat output 

Table C.1 ― Boilers 

Boiler Minimum efficiency in percent 

Heating boilers for solid fuels 75 

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Table C.2 ― Central heatings used for solid fossil and standardized biogenous fuels 

according to the nominal heat output 

Boiler Minimum efficiency 

% 

a) manually loaded 

 up to 10 kW 79 

 > 10 to 200 kW (71,3 + 7,7 log Pn) 

 > 200 kW 89 

b) automatically loaded 

 up to 10 kW 80 

 > 10 to 200 kW (72,3 + 7,7 log Pn) 

 > 200 kW 90 

NOTE Pn is the nominal heat output (QN in this standard). 

C.2.3 Emission limits 

Sub-clause 5.8 

Observation of the emission limits for solid fuels at nominal load and at minimum partial load, as specified by 

the manufacturer, shall be verified. 

These limits shall be proved at minimum partial load as specified by the manufacturer, not to exceed 50 % of 

nominal heat output for manually loaded small burners and 30 % of nominal heat output for automatically 

loaded small burners. 

Exceptions: manually loaded small burners 

a) For manually loaded small burners with a nominal heat output below 8 kW, the limit shall be proved only 

at nominal load. 

b) If the verification cannot be proved at the lowest partial load as specified by the manufacturer, the 

installation of a buffer tank shall be declared on the type plate and in the technical documentation. 

Exceptions: automatically loaded small burners 

c) For automatically loaded central heatings with a nominal heat output below 10 kW combined with a buffer 

tank, the emission limits and the efficiencies shall be proved only at nominal load. This shall be declared 

by the manufacturer on the type plate and in the technical documents. 

d) For room heaters and central heatings for wood pellets with a nominal heat output below 8 kW, the 

minimum partial load shall be proved at a heat output of 2,5 kW. 

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Table C.3 ― Small burners used for solid fuels manually loaded 

Emission limits 

mg/MJ 

Wooden fuels Other standardised 

biogenous fuels 

Fossil fuels 

Parameter Room 

heaters 

Central 

heaters 

< 50 kW 

nominal 

heat output

> 50 kW 

nominal 

heat output

< 50 kW 

nominal 

heat output 

> 50 kW 

nominal 

heat output

CO 1100 500 1100 500 1100 500 

NOx 150 150/100a 300 300 100 100 

OGC 80/50a 50/30a 50 30 80 30 

Dust 60/35a 50/30a 60/35a 60/35a 50/35a 50/35a

a Values applying as from 1.1. 2015. 

Table C.4 ― Small burners used for solid fuels automatically loaded 

Parameter 

Emission limits 

mg/MJ 

Wood pellets 

Room heaters 

Wood pellets 

Central heaters 

Other wooden 

fuels 

Other 

standardised 

biogenous fuels 

CO 500a 250a 250a 500a

NOx 150/100b 150/100b 150 / 100b 300 

OGC 30 30/20b 30 30/20b

Dust 50/25b 40/20b 50 / 30b 60 / 35b

a The limit value can be exceeded by 50 % during partial load operation at 30 % of nominal output. 

b Values applying as from 1.1. 2015. 

For systems with a nominal heat output above 50 kW that are subject to trade law, the requirements of the 

regulation for firing systems shall be fulfilled. 

C.3 Deviations from CROATIA 

Clause 4.4.7 

Table 6: Emission limits 

The emission limits are regulated in Chapter VII., Article 107, 108, 109, and 111 of Croatian Regulation About 

Maximum Emission Values of Pollution Components from Stationary Sources, (GVE - NN 21/2007). 

Boilers operated with solid fuels shall be put into operation if they fulfil the following specifications of the 

Regulation: Emission limits for Croatia. 

Table C.5 — Maximum heat losses by combustion products 

Nominal heat output, kW Heat losses, % 

100 - 1000 17 

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69 

Table C.6 — Emission limits for solid fuelsa

Nominal heat output, kW CO mg/m3 

at 7% O2 for coal 

11 % O2 for wood and biomass

100 - 1000 1000 

a Emissions are referred to dry exit flue gas, 0 °C, 1013,3 mbar. 

Limits for flue gas darkness: No. 1 according to the Ringelmann scale. 

C.4 Deviations from DENMARK 

C.4.1 Sub-clause 4.4.2 Boiler Efficiency 

According to the Danish Construction Code BR08, Clause 8.5.1.4, Sub-clause 7, boilers for coal, coke, bio 

fuel or biomass shall have an efficiency equivalent to Class 3 in EN 303-5. 

η = 67 + 6 log QN 

For boilers above 300 kW, the requirement corresponding to 300 kW shall be used. 

C.4.2 Sub-clause 4.4.7 Emission Limits 

According to the Danish EPA Statutory Order no. 1432 of 11/12/2007, only Class 3 (or higher) is acceptable 

for Denmark. 

Table C.7 ― Emission limits for Denmark 

Stoking Fuel Nominal 

heat output 

Emission limitsa

CO OGC Dust 

mg/m3 at 10 % O2

kW 

class class class 

3 3 3 

manual biogenic ≤ 50 5 000 150 150 

> 50 to 150 2 500 100 150 

> 150 to 300 1 200 100 150 

fossil ≤ 50 5 000 150 125 

> 50 to 150 2 500 100 125 

> 150 to 300 1 200 100 125 

automatic biogenic ≤ 50 3 000 100 150 

> 50 to 150 2 500 80 150 

> 150 to 300 1 200 80 150 

fossil ≤ 50 3 000 100 125 

> 50 to 150 2 500 80 125 

> 150 to 300 1 200 80 125 

a

 Refering to dry exit flue gas, 0 °C, 1 013 mbar. 

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C.4.3 Sub-clause 5.1 Test Base 

According to the Danish EPA Statutory Order no. 1432 of 11/12/2007, the type test shall be carried out by a 

laboratory which is accredited under the European cooperation for Accreditation (EA). 

C.4.4 Clause 8 Technical documentation, supplied with boiler 

According to the Danish EPA Statutory Order no. 1432 of 11/12/2007, a test certificate shall accompany the 

boiler and a copy shall be signed by the local chimney sweeper. 

C.5 Deviations from Germany 

C.5.1 Clause 4.4.7 Emission limits 

Table 7 Emission limits 

The emission limits are regulated in Chapter 2, paragraphs 4, 5 and Annex 2 of the German Immission 

Control Ordinance "Erste Verordnung zur Durchführung des Bundes-Immissionsschutzgesetzes (Verordnung 

über kleine und mittlere Feuerungsanlagen - 1. BImSchV)". 

Boilers operated with solid fuels shall only be installed, possess the quality and be put into operation if they 

fulfil the following specifications of the 1. BImSchV: 

Table C.8 ― Emissions for boilers operated with solid fuels shall not exceed the following limits from 

the given dates on: 

 Fuel acc §3 

article 1 

Nominal 

output range 

kW

Dust 

g/m3

CO 

g/m3

Stage 1: appliances, 

which will be installed 

after the 22.03.2010 

Number 1 to 3a ≥ 4 ≤ 500 0,09 1,0 

> 500 0,09 0,5 

Number 4 to 5 ≥ 4 ≤ 500 0,10 1,0 

> 500 0,10 0,5 

Number 5a ≥ 4 ≤ 500 0,06 0,5 

> 500 0,06 0,5 

Number 6 to 7 ≥ 30 ≤ 100 0,10 0,8 

> 100 ≤ 500 0,10 0,5 

> 500 0,10 0,3 

Stage 2: appliances, 

which will be installed 

after the 31.12.2014 

Number 1 to 5a ≥ 4 0,02 0,4 

Number 6 to 7 ≥ 30 ≤ 500 0,02 0,4 

> 500 0,02 0,3 

Number 8 to 13 ≥ 4 < 100 0,02 0,4 

NOTE Differing from sentence 1 for firing systems (appliances) which will exclusively be fired 

by fuels according §3 article 1 Number 4 in the form of split logs, the limits according Stage 2 apply 

for firing systems (appliances) when they will be installed after the 31.12.2016. 

The fuels mentioned in column 2 are described in §3 of the 1.BImSchV: 

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a) In firing systems (appliances) according to §1, only the usage of the following fuels is allowed: 

1. anthracite, not tar bonded anthracite briquette, anthracite coke; 

2. lignite, lignite briquettes, lignite coke; 

3. peat, peat pellets; 

3a. barbeque charcoal, barbeque charcoal briquettes (according to DIN EN 1860, version September 

2005); 

4. natural finished lumpy wood (including adhered bark), in particular in the form of split logs and wood 

chips, as well as brush-wood and cones; 

5. natural finished non-lumpy wood, in particular in the form of saw dust, shavings and abrasive dust, as 

well as bark; 

5a. pellets from natural finished wood in form of wood briquettes according to DIN 51731 version October 

1996, or in form of wood pellets according to the requirements for the fuels under the DINplus certification 

program DIN 51731-HP 5 "wood pellets for the usage in small firing installations according to DIN 51731-

HP 5", version August 2007, as well as other wood pellets out of natural finished wood of the same 

quality; 

6. coated, varnished or laminated wood as well as the remains, as far as no wood preservative has been 

applied or is contained due of a treatment and the laminates do not contain halogens in organic bonding 

or heavy metals; 

7. plywood, chipboards, fibreboards or otherwise glued wood as well as the remains, as far as no wood 

preservative has been applied or is contained due to a treatment and the laminates do not contain 

halogens in organic bonding or heavy metals; 

8. straw and similar herbal substances, corn not used for foodstuffs such as grain and bevelled grain 

punches, total grain plants, grain strip waste, husk and corn stalk remains, as well as pellets out of the 

aforementioned fuels; 

9. heating oil, extra light (Heizöl EL) according to DIN 51603-1, version August 2008, as well methanol, 

ethanol, natural finished vegetable oil or rapeseed methyl ester; 

10. gases of the public gas supply, natural finished gas or petroleum gas with comparable contents of 

sulphur as well as liquefied gas of hydrogen; 

11. sewer gas with a volumetric content of sulphur compounds up to 1 per mill, stated as sulphur, or 

biogas out of agriculture use; 

12. coke oven gas, mine damp, steel gas, blast furnace gas, refinery gas and synthetic gas with a 

volumetric content of sulphur compounds up to 1 per mill stated as sulphur; or 

13. other renewables, as far as these fulfil the requirements of paragraph 5. 

b) The mass content of sulphur of the named fuels in paragraph 1 numbers 1 and 2 shall not exceed one 

percent of the raw substance. For anthracite briquettes or lignite briquettes this requirement is fulfilled if, by a 

special pre-treatment, an equal limitation of the emissions of sulphur dioxide in the combustion components is 

assured. 

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72 

C.5.2 Clause 5.9 

Determination of the emission values: Annex 2 of the 1. BImSchV is valid. 

C.6 Deviations from Switzerland 

Clause 4.4.7, Table 7

The emission limits are regulated in Annex 4 of the Swiss Ordinance on Air Pollution Control ([OAPC] SR 

814.318.142.1) of 1985-12-16 (as at 2010-07-15). 

Boilers operated with woody biomass shall only be put on the market if they fulfil the following specifications of 

the OAPC: 

 declarations of conformity (Figure 20 OAPC); 

 Figures 1, 212, 23 Annex 4 OAPC; 

 Figures 31, 32 Annex 5 OAPC. 

Emissions for boilers operated with coal or wood fuels shall not exceed the following limits: 

Table C.9 ― Emission limits (from Annex 4 Figure 212 OAPC) 

Type of installation According to 

the norm 

Particular requirements (emission limits)a

 for carbon 

monoxide (CO) and particulate matter (Dust) 

Boilers for log wood 

and boilers for coal, 

manual stoking 

EN 303-5 or 

EN 12809 

CO: 800 mg/m3

dust: 50 mg/m3

Boilers for chipped 

wood and boilers for 

coal, 

automatic stoking 

EN 303-5 or 

EN 12809 

CO: 400 mg/m3

dust: 60 mg/m3

Boilers for wood pellets, 

automatic stoking 

EN 303-5 or 

EN 12809 

CO: 300 mg/m3

dust: 40 mg/m3

a Referred to oxygen basis: 

– for boilers for natural state wood 13 % volume; 

– for boilers for coal 7 % volume.

The sulphur content of coal, coal briquettes and coke shall not exceed 3 %. 

Boilers operated with non-woody biomass shall comply with the following specifications of the OAPC: 

 Figures 741, 742, 743 Annex 2 OAPC; 

 Figures 81, 82 Annex 3 OAPC. 

According to Figure 743, Annex 2 OPAC, non-woody biomass, such as biogenic waste and products from 

agriculture, may only be burnt in boilers with a heat input of at least 70 kW. Such units need an approval and 

shall meet stronger emission limits according to Figure 742, Annex 2 OAPC. 

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C.7 Deviations from United Kingdom 

Clause 4.4.7 and Table 6 in revision of EN 303-5 

The Clean Air Act 1993 lays down legislative requirements regarding emissions from solid fuels and solid fuel 

fired appliances in Great Britain; similar legislation (the Clean Air Order 1981) covers Northern Ireland. The 

requirements of these instruments are more stringent than those in EN 303-5. The UK Government at this 

time does not envisage a change to its current legislation or to a lowering of its standards in this respect. The 

UK therefore requires an A-deviation for Clause 4.4.7 and Table 7 of this standard. 

The emission requirements stated in EN 303-5 conflict with UK law in that Section 1 (1) of the UK 1993 Clean 

Air Act states "Dark smoke shall not be emitted from a chimney of any building, and if, on any day, dark 

smoke is so emitted, the occupier of the building shall be guilty of an offence." In applying this general 

regulation to domestic dwellings, the Clean Air Act 1993 gives local authorities the power to designate Smoke 

Control Areas within which it is an offence to emit smoke. The 1993 Act in Section 20(4) (prohibition of smoke 

emissions in smoke control area) states "... it shall be a defence to prove that the alleged emission of smoke 

was not caused by the use of any fuel other than an authorised fuel." 

In assessing an Authorised Fuel, the Minister has stated that one of the conditions to be satisfied is that the 

fuel when tested in an Open fire in accordance with BS 3841 shall not emit more than 5 g/h of solid particle 

matter. Once authorised by The Secretary of State, the fuel may then be burned in any domestic heating 

appliance without further assessment of its use on a specified appliance. 

Additionally, Section 21 of the 1993 Act states "The Secretary of State may by order exempt any class of 

fireplace, upon such conditions as he may specify in the order, from the provisions of Section 20 (prohibition 

of smoke emissions in smoke control area), if he is satisfied that such fireplaces can be used for burning fuel 

other than authorised fuels without producing any smoke or a substantial quantity of smoke". 

In assessing a domestic fireplace (i.e. stove, room heater or boiler etc.) for exemption to allow use in smoke 

control areas, the tests and emission guidelines of BS PD 6434 (covering domestic appliances of up to 45 kW 

nominal output) are employed. The tests and guidelines cover the measurement and evaluation of the 

desirable limits of emissions of solid particles at high, intermediate and low output and under conditions of 

misuse to ensure compliance under all possible continuously operating conditions and outputs. 

When assessing commercial and industrial appliances (generally having nominal outputs greater than about 

250kW), the smoke requirements stated in Schedule 1 of The Clean Air Act (Emissions of Grit and Dust from 

Furnaces) Regulations 1971 is employed to show compliance with the 1993 Act. In addition, where 

commercial and industrial appliances are installed in smoke control areas, the principles of BS PD 6434 are 

applied with testing at rated, low output and, where appropriate, misuse testing. Emission criteria applied 

include extrapolation of BS PD 6434 limits, plume visibility and an emission concentration limit under a range 

of operating conditions for the fuels to be burnt in them. 

Section 4(2) of the 1993 Act also states "No furnace shall be installed in a building or in any fixed boiler or 

industrial plant unless the furnace is, so far as is practicable, capable of being operated continuously without 

emitting smoke when burning fuel of a type for which the furnace was designed. 

The limits applied in the UK are detailed in Table C.10 below. The BS PD 6434 emission limit requirements 

are expressed in g/h based on heat output in accordance with the following formula: [5 + ((heat output in 

kW)/3)] (see also Table C.10), and the smoke emission is measured using an electrostatic precipitator 

arrangement which is shown diagrammatically in Figures C.1 and C.2. Therefore the class limits given in 

Table 6 of this European Standard are not applicable to the UK Legislation. 

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Table C.10 ― Summary of UK Clean Air Act 1993 emission controls for solid fuel appliances 

Location and appliance type Limit Reference 

In Smoke Control Area 

Domestic, < 45 kW output (5+ ((Output in kW)/3)) (in g/h) 5 tests at rated output, low 

output and, if appropriate, 

intermediate output. Also 

misuse tests. PD 6434 

Non-domestic (5+ ((Output in kW)/3)) (in g/h) BS PD 6434 (extrapolated) 

 Ringelmann Shade 1 BS 2742 

 150 mg/m3 for a dry gas at 0oC, 

101,3 kPa at stack O2 

Criterion developed based on 

custom and practise 

Outside Smoke Control Area 

Non-domestic As specified in Schedules 1 and 

2 of Regulations for solid fuel 

and oil-fired furnaces. Applies to 

furnaces larger than about 240 

kW (schedule 1) and 360 kW 

(schedule 2) 

Grit and Dust Regulations 1971. 

Tests at normal loading or 

maximum regular loading. 

 Ringelmann Shade 2 Clean Air Act 1993 (except as 

modified by the Dark Smoke 

(Permitted Periods) regulations 

1958, the Dark Smoke 

(Permitted Periods) (Vessels) 

regulations 1958 and the Clean 

Air (Emission of Dark Smoke) 

(Exemption) Regulations 1969. 

Clause 4.4.7 and Table 6 of EN 303-5 does not require testing or lay down particulate/smoke measurements 

with maximum limits for an appliance at low and intermediate output or under misuse conditions and therefore 

compliance with UK legislation in respect of all possible continuously operating conditions and outputs cannot 

be guaranteed for either domestic or commercial/industrial boilers. 

The inclusion of appliances up to 500 kW output will bring some EN 303-5 appliances under other UK 

legislation. Appliances >400 kW rated thermal input which the manufacturer claims, in addition to the fuels 

covered by the scope of EN 303-5, can also burn for example other solid fuels such as biomass waste from 

furniture, timber processing or joinery activities1) are regulated in the UK. The emission limits are specified in 

the Secretary of State’s Process Guidance Note PG1/12. The emission limits are summarised in Table C.11 

below. 

For these facilities, compliance with emission limits is demonstrated by continuous and/or annual compliance 

emission monitoring. The specified test procedure for particulate is ISO 9096. 

 

1) Process Guidance Note PG1/12 (12) : Secretary of State's Guidance for Combustion of Waste Wood February 2012, 

UK. Published by Defra and the Devolved Administrations and available here (accessed 20 March 2012): 

http://www.defra.gov.uk/environment/quality/pollution/ppc/localauth/pubs/guidance/notes/pgnotes/documents/pg1-12.pdf . 

Note that these are installations burning wastes which are exempt from the provisions of the EC Directive 2000/76/EC on 

incineration of waste. 

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Table C.11 ― Process Guidance Note 1/12 (12) – Statutory Guidance for Combustion of Waste Wood 

Substance Limit Comment 

Total Particulate Matter 60 mg/m3 

(new plant) 

66 mg/m3

 at 10 % O2. Continuous 

monitoring and annual compliance test 

Organic compounds 50 mg/m3 55 mg/m3 at 10 % O2. Annual compliance 

test 

Carbon monoxide 250 mg/m3 

(new plant, <1MW) 

275 mg/m3

 at 10 % O2. Continuous 

monitoring and annual compliance test 

Oxides of nitrogen 400 mg/m3 

(new plant) 

440 mg/m3

 at 10 % O2. On commissioning 

Smoke Ringelmann shade 1 

Odour No offensive odour 

beyond the site 

boundary 

Oxygen Not applicable Continuous monitoring 

NOTE All limits are at 0 oC, 101,3 kPa and 11 % O2 unless indicated otherwise. 

Clause 4.4.7 of EN 303-5 does not require continuous monitoring or lay down frequency of particulate 

measurements or specify the test method (ISO 9096) and therefore compliance with UK legislation cannot be 

guaranteed for those boilers which fall within the scope of PG1/12. 

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Key 

1 collecting electrodes 

2 skirt 

3 insulators 

4 upper end frame 

5 lower end frame 

6 inner mounting bracket 

7 outer mounting bracket 

8 suspension hook 

9 tension spring 

10 charged electrodes 

11 main frame made from aluminium alloy hexagonal tubes welded at the ends to the dished and pieces 

12 elevation 

NOTE Tubes are omitted from positions marked x in section A-A. 

Figure C.1 ― General arrangement of electrostatic precipitator 

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Dimensions in millimetres 

Key 

1 pressure measuring point 

2 to fan and outside air 

3 drought control damper 

4 hood 

5 electrostatic precipitator 

6 locating ring 

7 base plate for safety cage 

8 chimney 

Figure C.2 ― Electrostatic precipitator positioned for smoke collection 

C.8 Deviations for Italy 

Sub-clause 4.4.6 

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Table 6 Emission limits 

EN 303-5 differs from the Italian law: Decreto legislativo n. 152 del 3 aprile 2006 "Norme in materia 

ambientale" (G.U. Serie generale n. 88 – 14/4/2006) (Legislative Decree n. 152 -3 April 2006 - “Regulation on 

environmental matter” - G.U. General n. 88 – 14/4/2006). 

Therefore the following A-Deviation shall be taken into account. 

Italian DLgs 152/2006, Annex IX, Part 3, Section 2 states as following: 

Excerpt 

Biomass heating plants shall respect the following emission limits, with regard to 1 hour running period under 

most required conditions: 

Table C.12 

Plant nominal thermal output (MW) >0,035 ÷ <0,15 > 0,15 ÷ <1 

Total Particulate Matter 200 mg/Nm3 100 mg/Nm3

Total Organic Carbon (COT) 

Carbon Monoxide (CO) 

- 

350 mg/Nm3

Nitrogen Dioxide (expressed as NO2) 500 mg/Nm3

Sulphur Dioxide (expressed as SO2) 200 mg/Nm3

NOTE Emissions refer to an 11% O2 concentration. 

Concerning biomass for energy purposes, the decree allows only the use of (excerpt): 

a) Vegetable material from forestry activity, forest maintenance and pruning (mainly compiles to class 

1.1 in EN 14961-1:2010); 

b) Vegetable material produced by exclusively mechanical processes on: untreated wood made by bark, 

sawdust, chips, ....(omission) not contaminated by pollutants (mainly compiles to class 1.2.1 in 

EN 14961-1:2010. 

Moreover, Italian DLgs 152/2006, Annex IX, Part 3, Section 1 states the following limits: 

Table C.13 — Italian emission limits for heating plants fuelled with non-biomass solid fuels 

 6% O2

Nominal thermal output (MW) > 0,35 

Total Particulate Matter 50 mg/Nm3

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Annex ZA 

(informative)

Relationship between this European Standard and the Essential 

Requirements of EU Directive 2006/42/EC Machinery Directive 

This European Standard has been prepared under a mandate to CEN by the European Commission and the 

European Free Trade Association to provide a means of conforming to Essential Requirements of the New 

Approach Directive 2006/42/EC Machinery Directive. 

Once this standard is cited in the Official Journal of the European Union under that Directive and has been 

implemented as a national standard in at least one Member given State, compliance with the clauses referred 

to in this standard confers, within the limits of the scope of this standard, a presumption of conformity with the 

corresponding Essential Requirements of that Directive and associated EFTA regulations. 

WARNING — Other requirements and other EU Directives may be applicable to the product(s) falling 

within the scope of this standard. 

Table ZA.1 ― Correspondence between this European Standard and Directive 2006/42/EC 

Clause Hazards Hazardous situations 

or hazards events 

References 

GENERAL PRINCIPLES 

1 risk assessment 4.3; 5.16; Annex B 

2 conditions foreseen • normal operating conditions 

• foreseeable abnormal situations 

4 

1 ESSENTIAL HEALTH 

AND SAFETY 

REQUIREMENTS 

 4.2.4; 4.3; 5.12; 5.13; 

5.14; 5.15; 5.16 

1.1.2 Principles of safety 

integration 

 4.2.3; 4.3; 5.13; 5.14; 

5.15; 5.16 

1.1.3 Materials and products 4.1; 4.2.2; 4.2.3; 5.5.2 

1.1.5 Design of machinery to 

facilitate its handling 

 4.2.3 

1.1.6 Ergonomics not relevant 

1.2 CONTROL SYSTEMS 4.3.8; 5.13 

1.2.1 Safety and reliability of 

control systems 

 4.3.8; 4.3.9; 5.13; 5.14 

1.2.2 Control devices 4.3.8; 4.3.9; 5.13; 5.14 

1.2.3 Starting 5.7.4 

1.2.4 Stopping not relevant 

1.2.4.1 Normal stop not relevant 

1.2.4.2 Operational stop not relevant 

1.2.4.3 Emergency stop not relevant 

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Table ZA.1 (continued)

Clause Hazards Hazardous situations 

or hazards events 

References 

1.2.4.4 Assembly of machinery 8.2 

1.2.6 Failure of the power 

supply 

 4.3; 5.14; 5.16 

1.3 Protection against 

mechanical hazards 

 4; 5 

1.3.4 surfaces, edges or 

angles 

Burning, cuts; injuries 4.2 

1.3.5 combined machinery Wrong connection not relevant 

1.3.6 variations in operating 

conditions 

Overheating, fire, high pressure 4; 5 

1.3.7 moving parts Bruise, detach e.g. fingers 4; 5 

1.4 REQUIRED 

CHARACTERISTICS 

OF GUARDS AND 

PROTECTIVE DEVICES 

 4 

1.5.1 Electrical supply The safety objectives set out in 

EN 60335-2-102 shall apply 

4.3.9.2 

1.5.3 Energy supply other than 

electricity 

 4.3 

1.5.4 Errors of fitting Bruise, detach e.g. fingers, 4; 5 

1.5.5 Extreme temperatures Surface temperature, temperature of 

control and safety devices 

4.3, 5.2, 5.12; 5.7.2 

1.5.6 Fire 4; 5 

1.5.7 Explosion 4.3 

1.5.8 Noise 4.1; 8.2 

1.5.10 Radiation not relevant 

1.5.11 External radiation not relevant 

1.5.16 Lighting not relevant 

1.6 MAINTENANCE 4.2; 8.3 

1.6.1 Machinery maintenance 4.2; 8.3 

1.6.2 Access to operating 

positions and servicing 

points 

 4.2; 5.16 

1.6.3 Isolation of energy 

sources 

 not relevant 

1.6.5 Cleaning of internal parts 8.3 

1.7 Information 7 

1.7.1 Information and warnings 

on the machinery 

 7 

1.7.2 Warning of residual risks not relevant 

1.7.3 Marking of machinery 7 

1.7.4 Instructions 8 

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81 

Bibliography 

[1] EN 12619, Stationary source emissions — Determination of the mass concentration of total gaseous 

organic carbon at low concentrations in flue gases — Continuous flame ionisation detector method

[2] EN 13526, Stationary source emissions — Determination of the mass concentration of total gaseous 

organic carbon in flue gases from solvent using processes — Continuous flame ionisation detector 

method

[3] EN 14789, Stationary source emissions — Determination of volume concentration of oxygen (O2) — 

Reference method — Paramagnetism

[4] EN 14792, Stationary source emissions — Determination of mass concentration of nitrogen oxides 

(NOx) — Reference method: Chemiluminescence

[5] EN 15036-1, Heating boilers ― Test regulations for airborne noise emissions from heat generators ―

Part 1: Airborne noise emissions from heat generators

[6] EN 15058, Stationary source emissions — Determination of the mass concentration of carbon 

monoxide (CO) — Reference method: Non-dispersive infrared spectrometry

[7] EN 22553, Welded, brazed and soldered joints — Symbolic representation on drawings (ISO 2553)

[8] EN 60730-2-9, Automatic electrical controls for household and similar use ― Part 2-9: Particular 

requirements for temperature sensing controls (IEC 60730-2-9)

[9] EN ISO 13919-1, Welding — Electrons and laser beam welded joints — Guidance on quality levels for 

imperfections ― Part 1: Steel (ISO 13919-1)

[10] EN ISO 13919-2, Welding ― Electron and laser beam welded joints ― Guidance on quality levels for 

imperfections — Part 2: Aluminium and its weldable alloys (ISO 13919-2)

[11] EN ISO 15609-4, Specification and qualification of welding procedures for metallic materials — 

Welding procedure specification — Part 4: Laser beam welding (ISO 15609-4)

[12] EN ISO 15614-11, Specification and qualification of welding procedures for metallic materials — 

Welding procedure test — Part 11: Electron and laser beam welding (ISO 15614-11)

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