Heating boilers - Part 6: Heating boilers with forced draught burners - Specific requirements for the domestic hot water operation and energy performance of water heaters and combination boilers with atomizing oil burners of nominal heat input not exceeding 70 kW

This document is composed of two parts.
The first part supplements EN 303-1, EN 303-2, EN 303-4 and EN 304, hereafter called boiler standards. It specifies the supplementary requirements and tests for the construction, safety, rational use of energy, fitness for purpose, classification and marking related to the domestic hot water operation of oil-fired water heaters and combination boilers.
The domestic hot water is produced on either the instantaneous or storage principle. The domestic hot water production is integrated or coupled, the whole being marketed as a single unit.
The second part covers the energy performance of domestic hot water production of the appliances covered by the first part.
This second part sets out a method for assessing the energy performance of the appliances. It defines a number of daily tapping cycles for each domestic hot water use such as kitchen, shower, bath and a combination of these, together with corresponding test procedures, enabling the energy performances of combination boilers and water heaters to be compared and matched to the needs of the user.
The heat output of the appliances covered by this standard does not exceed 400 kW.
In the case of combination boilers, with or without storage tank, domestic hot water production is integrated or coupled, the whole being marketed as a single unit.
This standard only covers type testing.

Heizkessel - Teil 6: Heizkessel mit Gebläsebrennern - Spezielle Anforderungen an die trinkwasserseitige Funktion und energetische Bewertung von Wassererwärmern und von Kombi-Kesseln mit Ölzerstäubungsbrennern mit einer Nennwärmeleistung kleiner als oder gleich 70 kW

Dieses Dokument besteht aus zwei Teilen.
Der erste Teil vervollständigt die EN 303 1, EN 303 2, EN 303 4 und EN 304, nachfolgend Kesselnormen genannt. Er legt die zusätzlichen Anforderungen und Prüfungen für die Bauweise, die Sicherheit, die rationelle Energienutzung, die Gebrauchsgüte sowie die Einteilung und die Kennzeichnung bei der Betriebsart „Trinkwassererwärmung“ von ölbefeuerten Warmwasserbereitern und Kombi Kesseln fest.
Die Wassererwärmung erfolgt nach dem Durchlauf  oder dem Speicherprinzip und ist integriert oder angebaut. Die Funktionen „Heizwassererwärmung“ und „Trinkwassererwärmung“ werden als Einheit vertrieben.
Der zweite Teil behandelt die Gesamtenergieeffizienz der Funktionen „Heizwassererwärmung“ und „Trinkwarmwassererwärmung“ der im ersten Teil behandelten Geräte.
Dieser zweite Teil legt ein Verfahren zur Bewertung der Gesamtenergieeffizienz der Geräte dar. Er definiert eine Anzahl an täglichen Zapfzyklen für jede Verwendungsart der Trinkwassererwärmung, wie beispiels¬weise Küche, Dusche, Bad, und eine Kombination dieser, zusammen mit den zugehörigen Prüfverfahren, wodurch die Gesamtenergieeffizienz der Kombi Kessel und Warmwasserbereiter verglichen und auf die Bedürfnisse des Anwenders abgestimmt werden kann.
Die Wärmeleistung der von dieser Norm behandelten Geräte darf 400 kW nicht überschreiten.
Im Falle von Kombi Kesseln mit oder ohne Speicher werden die Funktionen „Heizwassererwärmung“ und „Trinkwassererwärmung“ als Einheit vertrieben.
Die vorliegende Norm umfasst nur die Typprüfung.

Chaudières de chauffage - Partie 6 : Chaudières avec brûleurs à air soufflé - Exigences spécifiques à la fonction eau chaude sanitaire et à la performance énergétique des préparateurs d'eau chaude et des chaudières à deux services avec brûleurs fioul à pulvérisation dont le débit calorifique nominal est inférieur ou égal à 70 kW

Le présent document se compose de deux parties.
La première partie complète les normes EN 303 1, EN 303 2, EN 303 4 et EN 304, ci-après désignées normes chaudières. Elle définit les exigences et les essais complémentaires pour la construction, la sécurité, l'utilisation rationnelle de l'énergie, l'aptitude à la fonction, ainsi que la classification et le marquage concernant la fonction eau chaude sanitaire des chauffe-eau et des chaudières à deux services fonctionnant au fioul.
L'eau chaude sanitaire est produite selon la conception instantanée ou à accumulation. La production d'eau chaude sanitaire est intégrée ou accolée, l'ensemble étant commercialisé comme une seule unité.
La deuxième partie concerne les performances énergétiques de la production d'eau chaude sanitaire des appareils couverts par la première partie.
Elle établit également une méthode d'évaluation des performances énergétiques des appareils. Elle définit un nombre de cycles quotidiens de puisage pour chaque utilisation d'eau chaude sanitaire (par exemple, cuisine, douche et/ou bain), ainsi que les procédures d'essai correspondantes, afin de faciliter la comparaison des performances énergétiques des chaudières à deux services et des chauffe-eau, et d'adapter ces performances aux besoins de l'utilisateur.
La puissance utile des appareils couverts par la présente norme n'excède pas 400 kW.
Dans le cas des chaudières à deux services, avec ou sans ballon, la production d'eau chaude sanitaire est intégrée ou accolée, l'ensemble étant commercialisé comme une seule unité.
La présente norme couvre uniquement les essais de type.

Kotli za gretje - 6. del: Kotli z ventilatorskimi gorilniki - Posebne zahteve za delovanje in energijske lastnosti grelnikov sanitarne vode in kombiniranih kotlov z razprševalnimi oljnimi gorilniki z nazivno močjo do vključno 70 kW

Ta evropski standard je sestavljen iz dveh delov.
Prvi del dopolnjuje standarde EN 303 1, EN 303 2, EN 303 4 in EN 304, ki so v nadaljevanju imenovani standardi za kotle. Določa dopolnilne zahteve in preskuse za konstrukcijo, varnost, racionalno uporabo energije, primernost za namen, klasifikacijo ter označevanje v zvezi z delovanjem oljnih grelnikov sanitarne vode in kombiniranih kotlov.
Topla sanitarna voda se proizvaja po načelu pretočnosti ali po načelu shranjevanja. Proizvodnja tople sanitarne vode je integrirana ali združena, pri čemer se celota trži kot ena enota.
Drugi del zajema energijske lastnosti proizvodnje tople sanitarne vode z napravami, ki so zajete v prvem delu.
Ta drugi del določa metodo za ocenjevanje energetskih lastnosti naprav. Določa število dnevnih ciklov izpuščanja za vsako uporabo tople sanitarne vode, npr. za kuhinjo, prho, kad in njihove kombinacije, skupaj z ustreznimi preskusnimi postopki, da se omogoči primerjava energijskih lastnosti različnih kombiniranih kotlov in grelnikov vode ter njihova uskladitev s potrebami uporabnika.
Toplotna moč naprav, ki so zajete v tem standardu, ne presega 400 kW.
Pri kombiniranih kotlih, z rezervoarjem ali brez, je priprava tople sanitarne vode integrirana ali združena, pri čemer se celota trži kot ena enota.
Ta standard zajema le tipsko preskušanje.

General Information

Status
Published
Publication Date
06-Aug-2019
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
07-Aug-2019
Completion Date
07-Aug-2019

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SLOVENSKI STANDARD
SIST EN 303-6:2019
01-oktober-2019
Nadomešča:
SIST EN 303-6:2001
Kotli za gretje - 6. del: Kotli z ventilatorskimi gorilniki - Posebne zahteve za

delovanje in energijske lastnosti grelnikov sanitarne vode in kombiniranih kotlov z

razprševalnimi oljnimi gorilniki z nazivno močjo do vključno 70 kW
Heating boilers - Part 6: Heating boilers with forced draught burners - Specific

requirements for the domestic hot water operation and energy performance of water

heaters and combination boilers with atomizing oil burners of nominal heat input not

exceeding 70 kW

Heizkessel - Teil 6: Heizkessel mit Gebläsebrennern - Spezielle Anforderungen an die

trinkwasserseitige Funktion und energetische Bewertung von Wassererwärmern und von

Kombi-Kesseln mit Ölzerstäubungsbrennern mit einer Nennwärmeleistung kleiner als
oder gleich 70 kW

Chaudières de chauffage - Partie 6 : Chaudières avec brûleurs à air soufflé - Exigences

spécifiques à la fonction eau chaude sanitaire et à la performance énergétique des

préparateurs d'eau chaude et des chaudières à deux services avec brûleurs fioul à

pulvérisation dont le débit calorifique nominal est inférieur ou égal à 70 kW
Ta slovenski standard je istoveten z: EN 303-6:2019
ICS:
27.060.30 Grelniki vode in prenosniki Boilers and heat exchangers
toplote
91.140.65 Oprema za ogrevanje vode Water heating equipment
SIST EN 303-6:2019 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 303-6:2019
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SIST EN 303-6:2019
EN 303-6
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2019
EUROPÄISCHE NORM
ICS 91.140.10; 91.140.65 Supersedes EN 303-6:2000
English Version
Heating boilers - Part 6: Heating boilers with forced
draught burners - Specific requirements for the domestic
hot water operation and energy performance of water
heaters and combination boilers with atomizing oil
burners of nominal heat input not exceeding 70 kW

Chaudières de chauffage - Partie 6 : Chaudières avec Heizkessel - Teil 6: Heizkessel mit Gebläsebrennern -

brûleurs à air soufflé - Exigences spécifiques à la Spezielle Anforderungen an die trinkwasserseitige

fonction eau chaude sanitaire et à la performance Funktion und energetische Bewertung von

énergétique des préparateurs d'eau chaude et des Wassererwärmern und von Kombi-Kesseln mit

chaudières à deux services avec brûleurs fioul à Ölzerstäubungsbrennern mit einer

pulvérisation dont le débit calorifique nominal est Nennwärmeleistung kleiner als oder gleich 70 kW

inférieur ou égal à 70 kW
This European Standard was approved by CEN on 10 June 2019.

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, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 303-6:2019 E

worldwide for CEN national Members.
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SIST EN 303-6:2019
EN 303-6:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 4

1 Scope .................................................................................................................................................................... 5

2 Normative references .................................................................................................................................... 5

3 Terms and definitions ................................................................................................................................... 6

4 Constructional requirements ..................................................................................................................... 8

4.1 General ................................................................................................................................................................ 8

4.2 Materials and method of construction of components of the domestic water circuit ........... 8

4.3 Domestic water connections ....................................................................................................................... 9

4.4 Soundness of the domestic water circuit ................................................................................................ 9

4.5 Adjusting, control and safety devices for the domestic hot water circuit .................................. 9

5 Operational requirements ........................................................................................................................... 9

5.1 General ................................................................................................................................................................ 9

5.2 Safety of the domestic hot water circuit ................................................................................................. 9

5.3 Rational use of energy ................................................................................................................................ 10

5.4 Fitness of purpose ........................................................................................................................................ 10

6 Test methods ................................................................................................................................................. 11

6.1 General ............................................................................................................................................................. 11

6.2 Safety of the domestic hot water circuit .............................................................................................. 11

6.3 Rational use of energy ................................................................................................................................ 13

6.4 Fitness for purpose ...................................................................................................................................... 15

7 Energy efficiency for hot water production ........................................................................................ 18

7.1 Reference conditions .................................................................................................................................. 18

7.2 Measurement uncertainties ..................................................................................................................... 19

7.3 Test conditions .............................................................................................................................................. 19

8 Determination of the energy consumption of the appliance ........................................................ 20

8.1 General ............................................................................................................................................................. 20

8.2 Tapping cycles ............................................................................................................................................... 20

8.3 Measurement of the energy recovered by the useful water ......................................................... 29

8.4 Calculation of heating oil energy ............................................................................................................ 30

8.5 Calculation of daily electrical energy .................................................................................................... 31

8.6 Measurement of heating oil and electrical energy consumptions in standby mode ........... 32

8.7 Measurement of daily auxiliary energy consumption in off mode............................................. 33

9 Determination of the wasted water ....................................................................................................... 33

10 Eco design related products data ........................................................................................................... 34

10.1 Water heating energy efficiency ............................................................................................................. 34

10.2 Annual fuel consumption (AFC) .............................................................................................................. 35

10.3 Annual electricity consumption (AEC) ................................................................................................. 35

11 Marking and instructions .......................................................................................................................... 36

11.1 Marking of the boiler and/or the tank ................................................................................................. 36

11.2 Instructions .................................................................................................................................................... 36

Annex A (informative) Test conditions ............................................................................................................. 38

Annex B (informative) Test rig and measurement devices ....................................................................... 41

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EN 303-6:2019 (E)

Annex ZA (informative) Relationship between this European Standard and the eco-design

requirements of Commission Regulation (EC) No 814/2013 aimed to be covered.............. 45

Annex ZB (informative) Relationship between this European Standard and the eco-design

requirements of Commission Regulation (EC)No 812/2013 aimed to be covered .............. 46

Annex ZC (informative) Relationship between this European Standard and the eco-design

requirements of Commission Regulation (EC) No 813/2013 aimed to be covered.............. 47

Annex ZD (informative) Relationship between this European Standard and the eco-design

requirements of Commission Regulation (EC) No 811/2013 aimed to be covered.............. 48

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SIST EN 303-6:2019
EN 303-6:2019 (E)
European foreword

This document (EN 303-6:2019) has been prepared by Technical Committee CEN/TC 57 “Central

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 February 2020, and conflicting national standards

shall be withdrawn at the latest by February 2020.

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

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN 303-6:2000.
EN 303-6 is revised to update it for:

— EN 13203-1 for the specific flow rate where a new method replaced the method used in EN 625

which was deleted (replaced partially by EN 15502-1 and EN 13203-1);

— ERP requirements for water heating appliances based on the work done by CEN/TC 109 WG4 in the

revision of EN 13203-2.

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

— EN 303-5, Heating boilers — Part 5: Special heating boilers for solid fuels, hand and automatically

stoked, nominal heat output of up to 300 kW — Terminology, requirements, testing and marking

— EN 304, Heating boilers — Test code for heating boilers for atomizing oil burners

Annexes A and B of this European Standard are informative.

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 Annexes ZA, ZB, ZC and ZD, which are an integral

part of this document.

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, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
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SIST EN 303-6:2019
EN 303-6:2019 (E)
1 Scope
This document is composed of two parts.

The first part supplements EN 303-1, EN 303-2, EN 303-4 and EN 304, hereafter called boiler standards.

It specifies the supplementary requirements and tests for the construction, safety, rational use of

energy, fitness for purpose, classification and marking related to the domestic hot water operation of

oil-fired water heaters and combination boilers.

The domestic hot water is produced on either the instantaneous or storage principle. The domestic hot

water production is integrated or coupled, the whole being marketed as a single unit.

The second part covers the energy performance of domestic hot water production of the appliances

covered by the first part.

This second part sets out a method for assessing the energy performance of the appliances. It defines a

number of daily tapping cycles for each domestic hot water use such as kitchen, shower, bath and a

combination of these, together with corresponding test procedures, enabling the energy performances

of combination boilers and water heaters to be compared and matched to the needs of the user.

The heat output of the appliances covered by this standard does not exceed 400 kW.

In the case of combination boilers, with or without storage tank, domestic hot water production is

integrated or coupled, the whole being marketed as a single unit.
This standard only covers type testing.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

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

EN 303-1:2017, Heating boilers — Part 1: Heating boilers with forced draught burners — Terminology,

general requirements, testing and marking

EN 303-2, Heating boiler —- Part 2: Heating boilers with forced draught burners — Special requirements

for boilers with atomizing oil burners

EN 304, Heating boilers — Test code for heating boilers for atomizing oil burners

EN 1057, Copper and copper alloys — Seamless, round copper tubes for water and gas in sanitary and

heating applications

EN 13203-2, Gas-fired domestic appliances producing hot water — Part 2: Assessment of energy

consumption

ISO 7-1, Pipe threads where pressure-tight joints are made on the threads — Part 1: Dimensions,

tolerances and designation

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

tolerances and designation
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EN 303-6:2019 (E)
3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 13203-2 and the following

apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
combination boiler

boiler designed both for central heating and for the production of domestic hot water

Note 1 to entry: Depending on its type of domestic hot water production, the combination boiler is classed as

follows, in accordance with the manufacturer’s declaration.
3.1.1
instantaneous type

combination boiler which can continuously supply the specific domestic hot water rate “D” stated by the

manufacturer
3.1.2
storage type

combination boiler which can intermittently supply the specific domestic hot water rate “D” stated by

the manufacturer
3.2
“summer” operating mode
operating mode in which the boiler only provides heating of the domestic water
3.3
specific rate

domestic hot water rate declared by the manufacturer, corresponding to a mean temperature rise of

30 K, that the boiler can supply in two successive delivery periods (in l/min)
3.4
nominal domestic hot water heat input

value of the heat input in the domestic hot water mode indicated by the manufacturer (in kW)

3.5
maximum water service pressure
PMS

maximum pressure permitted in the domestic water circuit, as declared by the manufacturer (in bar)

3.6
tank
reservoir of domestic water
3.7
thermal store

heat reservoir sited mainly in heating water, as opposed to the domestic hot water storage in the tank

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SIST EN 303-6:2019
EN 303-6:2019 (E)
3.8
pressure relief valve
valve that opens automatically at a given pressure to discharge hot water
3.9
thermostatic control of the domestic hot water operation

means of control in which the fuel rate is subordinated to a thermostatic device controlling the

domestic hot water temperature, the set point of the device may be adjustable
3.10
temperature holding thermostat

device which maintains the water in the tank or the thermal store at a given temperature

3.11
low inertia thermometer

measuring instrument with a response time such that 90 % of the final temperature rise, in the range

15 °C to 100 °C, is obtained within 5 s when the sensor is plunged into still water

3.12
nominal domestic hot water input

value of the heat input for the production of domestic hot water stated in the instructions (in kW)

3.13
summer mode

conditions during which the appliance supplies energy only for the production of domestic hot water (is

also domestic hot water mode)
3.14
winter mode

conditions during which the combination boiler supplies energy for the production of domestic hot

water and space heating (the appliance produces domestic hot water and central heating hot water

simultaneously with a priority for domestic hot water production)

Note 1 to entry: A water heater operates always in summer mode, while a combination boiler operates in

summer and winter modes.
3.15
domestic water test temperature
temperature of the delivered water at which the tests are conducted
3.16
control cycle

time cycle for keeping components and/or the storage tank (if any) of the domestic hot water circuit at

predetermined temperature level

Note 1 to entry: It consists of an "ON" duration time during which the heating of the domestic hot water (by

liquid fuel and/or auxiliary energy) and an "OFF" duration time.
3.17
useful water

quantity of water delivered at the tap for which the temperature rise above the inlet water temperature

is in accordance with the requirement fixed for each individual delivery of the tapping cycles

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SIST EN 303-6:2019
EN 303-6:2019 (E)
3.18
wasted water

quantity of water delivered at the tap for which the temperature rise above the inlet water temperature

is not in accordance with the requirement fixed for each individual delivery of the tapping cycles

3.19
standby mode

operating state in which the appliance can provide domestic hot water at any time

Note 1 to entry: In the case of an appliance with a control cycle for keeping components and/or the storage tank

(if any) of the domestic hot water circuit at predetermined temperature level no tapping is made.

3.20
off mode

state of an appliance, selected by the user, in which domestic hot water cannot be provided

3.21
useful water flow rate

flow rate of water delivered at the tap for which the temperature rise above the inlet water temperature

is in accordance with the requirement fixed for each individual delivery of the tapping cycles

3.22
useful water temperature
water temperature, expressed in degrees Celsius, delivered at the tap
Note 1 to entry: Tap at the exit of the appliance.
3.23
appliance flow rate
flow rate delivered by the appliance before the mixing device, if applicable
3.24
appliance water temperature

water temperature, expressed in degrees Celsius, delivered by the appliance before the mixing device

4 Constructional requirements
4.1 General

It is checked that the assembly meets the constructional requirements by visual examination of the

boiler or the water heater and possibly the tank, and also by inspection of the technical file.

4.2 Materials and method of construction of components of the domestic water circuit

Materials shall be appropriate for their use, under intended application and at the maximum water

pressure stated by the manufacturer.

The requirements relating to thermal insulation and its use specified in the standards about boilers only

apply to parts of the domestic water circuit likely to come into contact with flames or sited close to the

combustion products outlet.

The materials of the parts containing domestic water shall not affect the quality of the domestic water

in respect of either health or taste.

The whole of the domestic hot water circuit shall be made up of corrosion resistant materials or shall be

protected against corrosion.
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EN 303-6:2019 (E)
4.3 Domestic water connections
Threaded connections shall comply with ISO 228-1 or ISO 7-1.

If copper tubes are used for the connection, the end of the tube shall comply with EN 1057.

In accordance with the manufacturer’s instructions, the domestic water circuit shall be able to be

drained, without the discharge of water compromising electrical safety.
4.4 Soundness of the domestic water circuit

The domestic hot water circuit and the heating circuit shall be separate. If an actuator or a control has a

sliding shaft or a link with the diaphragm separating the heating water circuit and the domestic water

circuit there shall be an air vent between these circuits. The area of this aperture shall be at least

19 mm and it shall be possible to introduce a 3,5 mm pin gauge into it.
4.5 Adjusting, control and safety devices for the domestic hot water circuit

The domestic hot water circuit shall be fitted with control and safety devices necessary to comply with

the requirements “Temperature sensing control type TR and temperature sensing control type STB” of

EN 303-1:2017, 4.1.2.6.

The tank shall be fitted with a device for controlling the water temperature. This device shall allow a

temperature to be attained which is sufficient to prevent the build-up of bacteria (see 5.2.3.3).

When local installations require a temperature relief valve operating at 100 °C, any device controlling

the temperature of the domestic hot water shall act before this valve.
5 Operational requirements
5.1 General

If the nominal heat input in domestic hot water mode exceeds the nominal heat input in the central

heating mode, the combination boiler shall be tested according to the EN 303-2 at the nominal heat

input in the domestic hot water mode.

A combination boiler certified with an atomizing oil burner will also meet the requirements of this

standard if the same boiler is fixed with a forced draught burner for gaseous fuels.

5.2 Safety of the domestic hot water circuit
5.2.1 Instantaneous and storage types
5.2.1.1 Soundness of parts containing domestic water

Under the test conditions of 6.2.1.1, the parts containing domestic water shall withstand the test

pressure without permanent distortion or soundness defects, with respect to the outside or the heating

circuit.
5.2.1.2 Overheating of the domestic hot water by the heating circuit

Under the test conditions of 6.2.1.2, the domestic hot water temperature shall not exceed 95 °C.

5.2.1.3 Failure of the domestic hot water temperature control device

Under the test conditions of 6.2.1.3, in the domestic water mode and in the event of failure of the normal

control the requirements for safety limiter (see EN 303-1:2017, 4.1.2.6) concerning the limit thermostat

or the safety temperature limiter shall be met.
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EN 303-6:2019 (E)
5.2.2 Instantaneous type
5.2.2.1 Maximum domestic hot water temperature

Under the test conditions of 6.2.2.1, the domestic hot water temperature shall not exceed 95 °C.

5.2.2.2 Overheating of the domestic hot water

Under the test conditions of 6.2.2.2, the domestic hot water temperature shall not exceed 95 °C.

5.2.3 Storage type
5.2.3.1 Maximum temperature of the domestic hot water

Under the test conditions of 6.2.3.1, the domestic hot water temperature shall not exceed 95 °C.

5.2.3.2 Overheating of the domestic hot water

Under the test conditions of 6.2.3.2 for boilers in which part of the tank is in contact with products of

combustion, the domestic hot water temperature shall not exceed 95 °C.
5.2.3.3 Temperature of the domestic hot water

Under the test conditions of 6.2.3.3, it shall be possible to adjust to or obtain a domestic hot water

temperature of at least 60 °C in the tank.
5.3 Rational use of energy
The considered useful efficiency is that measured in the central heating mode.
5.4 Fitness of purpose
5.4.1 Instantaneous and storage types — Specific water rate

Under the test conditions of 6.4.1, the measured value of the specific rate shall not be more than 5 %

below the value D stated by the manufacturer on the data plate.
5.4.2 Instantaneous type
5.4.2.1 Nominal domestic hot water heat input

Under the test conditions of 6.4.3.1, the nominal domestic hot water heat input shall be obtained or may

be adjusted to within ±5 %.
5.4.2.2 Water pressure to obtain the nominal heat input

Under the test conditions of 6.4.3.2, the heat input obtained shall be at least 95 % of the heat input

obtained in 6.4.3.1.
5.4.2.3 Obtaining the domestic hot water temperature

Under the conditions of 6.4.3.3, it shall be possible to achieve or adjust to a water rate that corresponds

to a temperature of between 50 °C and 80 °C for boilers with a thermostatic control or a temperature

rise at the boiler outlet of between 45 K and 65 K for boilers with proportioning control.

5.4.2.4 Heating-up time of the domestic hot water

Under the test conditions of 6.4.3.4, the heating-up time shall not exceed 2 min.

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SIST EN 303-6:2019
EN 303-6:2019 (E)
6 Test methods
6.1 General
6.1.1 Test conditions

Unless otherwise specified, the general test conditions of the standards about boilers are supplemented

as stated below:
— cold water: (10 ± 2) °C;
— hot water: 50 °C or as near as possible;

— central heating water (if necessary): see standards about boilers (flow 80 °C − return 60 °C).

For the tests:

— the domestic water pressure is the difference between the static inlet and outlet pressures of the

boiler measured as close as possible to the boiler;

— the inlet and outlet temperatures of the domestic water are measured in the centre of the flow and

as close as possible to the boiler.
In certain tests, a low inertia thermometer is used.
6.1.2 Adjustment of the domestic water pressure

The domestic water pressure shall be adjusted to the required value within a tolerance of ±4 %.

6.1.3 Operation of the boiler

Except where otherwise specified, the tests are carried out with the boiler operating in the domestic

water mode and the “summer” operating mode.
6.2 Safety of the domestic hot water circuit
6.2.1 Instantaneous and storage types
6.2.1.1 Soundness of the parts containing domestic water
The domestic water circuit is subjected to a pres
...

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