oSIST prEN 304:2023
(Main)Heating boilers - Test code for heating boilers for atomizing oil burners
Heating boilers - Test code for heating boilers for atomizing oil burners
This document applies to the determination of the performances of heating boilers and combi boilers fired by liquid fuels. The requirements for the heating performances are laid down in EN 303-1 and EN 303-2.
This test code includes the requirements and recommendations for carrying out and evaluating the procedure for testing boilers and also the details of the technical conditions under which the tests will be carried out.
The requirements and the performance of testing for the sanitary hot water production of combi boilers are laid down in EN 303-6.
Heizkessel - Prüfregeln für Heizkessel mit Ölzerstäubungsbrennern
Dieses Dokument wird zur Ermittlung der Leistung von mit flüssigen Brennstoffen befeuerten Heizkesseln und Kombi-Kesseln angewendet. Die Anforderungen an die Heizleistungen sind in EN 303-1 und EN 303-2 festgelegt.
Die Prüfregeln enthalten die Anforderungen und Empfehlungen für die Durchführung und Auswertung des Verfahrens zur Prüfung von Kesseln sowie Angaben über die technischen Bedingungen, unter denen die Prüfungen stattfinden.
Die Anforderungen und die Durchführung von Prüfungen für die sanitäre Warmwasserbereitung von Kombi-Kesseln sind in EN 303-6 festgelegt.
Chaudières de chauffage - Règles d'essai pour les chaudières avec brûleurs fioul à pulvérisation
Le présent document s'applique à la détermination des performances des chaudières de chauffage et des chaudières à deux services fonctionnant avec des combustibles liquides. Les exigences relatives aux performances de chauffage sont établies dans l’EN 303-1 et l’EN 303-2.
Ces règles incluent les exigences et les recommandations relatives à la réalisation et à l'évaluation de la procédure d'essai des chaudières ainsi qu'aux détails des conditions techniques dans lesquelles seront réalisés les essais.
Les exigences et la réalisation des essais relatifs à la production d'eau chaude sanitaire par des chaudières à deux services sont établies dans l'EN 303-6.
Kotli za ogrevanje - Preskušanje kotlov za ogrevanje z razprševalnimi oljnimi gorilniki
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN 304:2023
01-marec-2023
Kotli za ogrevanje - Preskušanje kotlov za ogrevanje z razprševalnimi oljnimi
gorilniki
Heating boilers - Test code for heating boilers for atomizing oil burners
Heizkessel - Prüfregeln für Heizkessel mit Ölzerstäubungsbrennern
Chaudières de chauffage - Règles d'essai pour les chaudières avec brûleurs fioul à
pulvérisation
Ta slovenski standard je istoveten z: prEN 304
ICS:
27.060.10 Gorilniki na tekoče in trdo Liquid and solid fuel burners
gorivo
91.140.10 Sistemi centralnega Central heating systems
ogrevanja
97.100.40 Grelniki na tekoče gorivo Liquid fuel heaters
oSIST prEN 304:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 304:2023
DRAFT
EUROPEAN STANDARD
prEN 304
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2023
ICS 91.140.10 Will supersede EN 304:2017
English Version
Heating boilers - Test code for heating boilers for
atomizing oil burners
Chaudières de chauffage - Règles d'essai pour les Heizkessel - Prüfregeln für Heizkessel mit
chaudières avec brûleurs fioul à pulvérisation Ölzerstäubungsbrennern
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 57.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 304:2023 E
worldwide for CEN national Members.
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oSIST prEN 304:2023
prEN 304:2023 (E)
Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 General conditions for testing . 6
5 Measurement accuracies and uncertainties . 6
6 Measurements for the heating mode . 7
6.1 General . 7
6.2 Determination of the nominal heat output . 7
6.3 Determination of the boiler efficiency at nominal heat output. 8
6.4 Performance of testing . 8
6.4.1 General test conditions . 8
6.4.2 Draught adjustment . 8
6.4.3 Establishment of steady-state conditions . 8
6.4.4 Test period . 8
6.5 Calculation . 8
6.5.1 General . 8
6.5.2 Nominal heat output . 9
6.5.3 Boiler heat input . 9
6.5.4 Boiler efficiency . 9
6.6 Determination of the waterside resistance . 9
6.7 Determination of the standby heat loss . 10
6.7.1 General . 10
6.7.2 Standby heat loss . 10
6.8 Efficiency at 30 % of the nominal heat output . 13
6.8.1 General . 13
6.8.2 Efficiency at 30 % - Method 1 (time dependent method) . 13
6.8.3 Efficiency at 30 % - Method 2 (load dependent method) . 13
6.9 Auxiliary electricity consumption . 15
6.10 Seasonal space heating efficiency . 15
6.11 Verification of nominal condensing output . 15
6.12 Formation of condensation . 15
6.13 Functional test for the temperature sensing control type TR and temperature
sensing control type STB on the boiler . 15
6.14 Surface temperature . 19
6.15 Floor temperatures . 19
6.16 Limiting temperature of the test panels . 19
6.17 Emission values of NO and CO . 20
x
6.17.1 General . 20
6.17.2 Units . 20
6.17.3 Assemblies of a boiler with various burners . 20
7 Measurement of the sanitary water production mode . 21
8 Test report and other documents . 21
2
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Annex A (normative) Calculations for the heating mode . 22
A.1 Volume measurement . 22
A.2 Calculation of combustion parameters . 22
A.3 Determination of air factor (𝜆𝜆) and excess air (e) . 26
A.4 Test rigs . 28
A.5 Calculation of the nominal heat output P . 29
N
A.6 Calculation of the heat input . 30
A.7 Calculation of efficiency . 30
A.8 Calculation of the heat losses q , q , q . 32
A U S
A.9 Standby heat loss (P ) . 35
Stby
A.10 Calculation of the seasonal space heating energy efficiency . 36
A.11 Fuel characteristics . 39
Annex B (informative) Applicable symbols and units . 41
Annex C (informative) Criteria for the adaptation of forced draught burners using liquid
fuels to heating boilers . 44
Annex D (informative) Information for setting up and evaluation of the test rig . 46
Annex E (informative) Determination of the heat losses of the test rig . 47
Annex F (informative) Alternative method for heat output as enthalpy difference. 48
F.1 General . 48
F2 Heat output calculation . 48
F.3 Water enthalpy (Hw) calculation . 49
F.4 Introduction. 49
F.5 Introduction. 50
Annex ZA (informative) Relationship between this European Standard and the ecodesign
requirements of Commission Regulation (EU) No [813/2013] aimed to be covered . 51
Annex ZB (informative) Relationship between this European Standard and the ecodesign
requirements of Commission Delegated Regulation (EU) No [811/2013] aimed to be
covered . 52
Bibliography . 53
3
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prEN 304:2023 (E)
European foreword
This document (prEN 304:2023) has been prepared by Technical Committee CEN/TC 57 “Central
heating boilers”, the secretariat of which is held by DIN.
This document will supersede EN 304:2017.
For relationship with EU Directive(s), see informative Annexes ZA and ZB, which are an integral part of
this document.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association, and supports essential requirements of EU
Directive(s) / Regulation(s).
For relationship with EU Directive(s) / Regulation(s), see informative Annexes ZA and ZB, which is an
integral part of this document.
The main technical changes compared to EN 303-2:2017 are the following:
a) new Annex F for calculation clarification was added;
b) new clause marking and instructions was added;
c) updated Normative References;
d) standby heat loss method 1 was deleted.
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1 Scope
This document applies to the determination of the performances of heating boilers and combi boilers
fired by liquid fuels. The requirements for the heating performances are laid down in EN 303-1 and
EN 303-2.
This test code includes the requirements and recommendations for carrying out and evaluating the
procedure for testing boilers and also the details of the technical conditions under which the tests will
be carried out.
The requirements and the performance of testing for the sanitary hot water production of combi boilers
are laid down in EN 303-6.
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 267:2020, Forced draught burners for liquid fuels
EN 303-1:2017, Heating boilers — Part 1: Heating boilers with forced draught burners — Terminology,
general requirements, testing and marking
EN 303-2:2017, Heating boilers — Part 2: Heating boilers with forced draught burners — Special
requirements for boilers with atomizing oil burners
1
EN 303-6, 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
EN 15456, Heating boilers — Electrical power consumption for heat generators — System boundaries —
Measurements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 303-1:2017 and
EN 303-2:2017 and the following apply.
3.1
minimum continuous heat output
P
minC
lowest heat output which is maintained automatically by the control device in continuous operation
which is specified for each type of fuel in accordance with the requirements of this document
1
As impacted by EN 303-6/prA1.
5
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4 General conditions for testing
The performance tests of the boiler should be carried out by a test laboratory complying with the
requirements of EN ISO/IEC 17025.
The test sample shall correspond to a boiler as placed on the market including all parts and accessories
necessary for the operation of the boiler. Boilers to be equipped with different burners shall be tested
with one specified forced draught burner.
The boiler and the burner shall be operated in accordance with the operation manual throughout all
tests.
When determining the thermal outputs P and 30 % P of a combi boiler, no sanitary hot water shall
N N
be drawn off during the test. The thermal outputs shall be determined from the heating circuit only.
Sanitary hot water tests for combination boiler shall be done according to EN 303-6.
5 Measurement accuracies and uncertainties
The accuracy of the measurement devices for the following parameters shall not exceed:
a) atmospheric pressure 50 Pa;
b) waterside pressure loss 2 % of measured value;
c) water flow rate 1 % of measured value;
d) air volume flow rate 2 % of measured value;
e) time
1) up to 1 h: 0,2 s;
2) beyond 1 h: 0,1 % of measured value;
f) auxiliary electrical energy 2 % of measured value;
g) temperatures:
1) ambient 2 K;
2) water 1 K;
3) combustion products 2 K;
4) surface 2 K;
h) CO, CO , O , NO , C H :
2 2 x x y
1) CO -content: 0,1 % volume from full scale;
2
2) O -content: 0,1 % volume from full scale;
2
3
3) CO-content: 5 ml/m ;
3
4) NO -content: 5 ml/m ;
x
6
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3
5) C H -content: 5 ml/m ;
x y
i) Mass 0,05 % of the full scale;
j) Pressure flue gas:
1) ≤ 60 Pa: 1Pa;
2) > 60 Pa: 2 % of the measured value.
The full range of the measuring apparatus shall be chosen in such a way that it is suitable for maximum
anticipated value. The measurement accuracies indicated above concern individual measurements.
For measurements requiring a combination of individual measurements, the lower accuracies
associated with individual measurements may be necessary to attain the total required uncertainty. The
test rig shall be set up in such a way that the efficiency can be determined within an uncertainty of 2 %
points.
6 Measurements for the heating mode
6.1 General
The amount of useful heat output transmitted to the heat carrier (water) is measured. It can be
determined in the boiler circuit or by means of a secondary heat exchanger.
The useful heat output transmitted to the water is determined either by measuring:
a) the mass flow of cold water entering the boiler circuit and the rise of temperature between the
outlet water temperature and the inlet water temperature; or
b) the mass flow of the water circulating in the boiler circuit and its temperature rise; or
c) the mass flow and the temperature rise over a secondary heat exchanger corrected by the heat loss
of this secondary heat exchanger. The heat produced by the boiler is transferred to the cooling
water by means of a secondary heat exchanger. The heat received by the latter is calculated from
the mass flow and the temperature rise of the cooling water. The heat losses from the well-
insulated connections between the boiler and the secondary heat exchanger and those of the
secondary heat exchanger itself, are determined either by preliminary tests or by calculation. The
heat output of the boiler is the sum of the two amounts of heat.
6.2 Determination of the nominal heat output
The tests for the determination of the nominal heat output shall be carried out at a firing rate such that
the output is at least 100 %, but does not exceed 105 % of the nominal value, and the requirements
concerning the nominal heat output shall be met.
If the heat output exceeds 105 %, a second test shall be carried out at a firing rate between 95 % and
100 % of the nominal heat output of the boiler.
The actual value for the nominal heat output shall be determined by linear interpolation between the
two test results.
The nominal heat output shall be determined at a water rate that is adjusted to obtain a return water
temperature of (60 ± 1) °C and a temperature difference between the flow and return water
temperature of (20 ± 2) °C.
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NOTE The conditions for determination of the rated heat output in former versions of EN 304 have been a
mean flow temperature of between 80 °C and 90 °C, and the mean temperature difference between flow and
return has been between 10 K and 25 K. However, this is not in line with the Regulation EU 813/2013.
6.3 Determination of the boiler efficiency at nominal heat output
The boiler efficiency at nominal heat output is measured as the determination of the nominal heat
output (see 6.2).
The efficiency shall be determined on the basis of the net calorific value NCV.
The direct method according to 6.5.4.1 shall be applied. The indirect method allows an additional check
of test accuracy of the test rig to be made by means of an energy balance.
6.4 Performance of testing
6.4.1 General test conditions
The boiler is installed in accordance with the technical instructions in a well-ventilated, draught free
room (air speed less than 0,5 m/s), which has an ambient temperature of (20 ± 5) K. The boiler is
protected from direct solar radiation.
The settings of the burner shall not be manually changed after adjustment. No change shall be made to
the water flow or any other test parameter during one test period.
The temperature, pressure and composition of the products of combustion shall be measured
continuously and shall be recorded with a sampling rate below 10 s.
The flow temperature t and the return temperature t shall not differ by more than ±0,5 K over the
F R
test period at the beginning and the end of the test period.
6.4.2 Draught adjustment
6.4.2.1 Boilers operating under negative pressure
For boilers operating under negative pressure the draught at the boiler outlet shall be adjusted so that
there is a negative pressure in the combustion chamber. The draught shall be measured.
6.4.2.2 Boilers operating under positive pressure
In positive pressure boilers the pressure shall be set at the boiler outlet close to 0 Pa. The pressure
difference between combustion chamber and boiler outlet shall be measured.
6.4.3 Establishment of steady-state conditions
The boiler shall be operated for at least 1 h before the start of the performance and efficiency test at the
output intended for the test without any further interference.
The steady-state condition is reached once the water temperatures t and t do not differ by more
F R
than ± 0,5 K.
6.4.4 Test period
The test period shall be at least 60 min.
6.5 Calculation
6.5.1 General
The calculations shall be based on the mean values of the individual readings of all recorded parameters
during the test period of 2 consecutive 30 min test sequences which meet the requirements of 6.4.4.
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6.5.2 Nominal heat output
The necessary formulae relevant to the individual test methods are given in A.5.
6.5.3 Boiler heat input
For these calculations, formulae in A.6 are to be used.
6.5.4 Boiler efficiency
6.5.4.1 Direct method
In the direct method the boiler efficiency shall be determined by:
P
(1)
η ×100
K
Q
B
P and Q as described in Annex A.
B
NOTE P equals either P or 30 % P
N N.
6.5.4.2 Indirect method
The indirect method is used for checking purposes only. The indirect boiler efficiency is given by:
(2)
η =1− q−−qq
k A US
where
q is the loss assensible heat of the products of combustion (values relative to the heat input);
A
q is the loss as incomplete combustion (values relative to the heat input);
U
q is the loss as radiation, convection and conduction (values relative to the heat input).
S
These heat losses are calculated in A.8.
6.6 Determination of the waterside resistance
The hydraulic resistance of a boiler (measured in mbar) shall be determined for the water rate
corresponding to operation of the boiler at the nominal heat input with a water flow temperature of
80 °C and a temperature difference between the flow and the return water of 20 K.
Other conditions are accepted if documented.
The test is carried out with the water at ambient temperature.
The test rig is specified in Figure 1. Before or after the test, the two test pipes are connected directly to
each other in order to determine their own resistance for the specified flow rate.
9
=
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Key
1 vent
2 differential manometer
3 flexible tubes
4 boiler
5 test pipe
a section at “X” rotated through 90°
6 flexible pipe
7 orifice ⌀ 3 mm smoothed internally
Figure 1 — Determination of the hydraulic resistance
6.7 Determination of the standby heat loss
6.7.1 General
No useful heat shall be extracted for heating or sanitary hot water production.
6.7.2 Standby heat loss
The test installation is described in Figures 3, 4 and 5.
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The circuits joining the different parts of the installation shall be insulated and as short as possible. The
inherent losses of the test installation and the thermal contribution of the pump for the different flow
rates shall be determined at the beginning to be able to take account of them (see Annex B).
The boiler is fitted with the largest diameter test flue stated by the manufacturer in the technical
instructions and equipped with a burner but is not in operation. Normally the test is carried out with a
burner without air dampers. If a burner with air dampers is used this shall be stated in the test report.
NOTE The ideal distance is 1 m.
The average boiler water temperature is brought to a mean temperature of (30 ± 5) K above ambient
temperature. The pump (11, Figure 2) and the boiler pump, if any, are stopped, the exchanger circuit
(12, Figure 2) is shut off.
With the water circulating continuously by means of the pump (5, Figure 2) of the test rig, the thermal
contribution of the electric boiler is adjusted so as to obtain, in the steady-state condition, a difference
of (30 ± 5) K between the mean water temperature and the ambient temperature.
Throughout the test the variation in room temperature shall not exceed 2 °C/h.
The following parameters shall be recorded:
— P in kW, the electrical power consumed by the auxiliary electric boiler, corrected for the losses of
m
the test rig and the thermal contribution of the pump (5, Figure 2);
— T in °C, the mean water temperature equal to the mean of the temperature indicated by the two
probes (2, Figure 2) at the return and the flow of the boiler during the test;
— T in °C, the mean ambient temperature during the test.
A
The standby heat loss, expressed for a mean water temperature of 30 K above an ambient temperature
of 20 °C are given in kW, by:
1,25
30
PP= (6)
stby m
−TT
A
Determination of the heat losses from the test rig and the heat contributions of the circulating pump of
the test rig are given in Annex E.
The standby losses of combi boilers with storage tank measured in method 2 of this document are
determined as described in EN 15502-1:2012+A1:2015, 9.4.2.
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Key
1 boiler with the burner
2 temperature probes
3 low inertia thermocouple
4 recorder
5 pump with a rate such that the temperature difference between the two probes is between 2 °C and 4 °C at
the maximum test temperature
6 auxiliary electric boiler
7 device for measuring the electric power
8 voltage regulator
9 1/4 turn valves
10 electrical supply
11 additional pump (if necessary)
12 heat exchanger
Figure 2 — Test installation to determine the heat emissions of the boiler when the burner is off
and the thermal capacity of the boiler
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6.8 Efficiency at 30 % of the nominal heat output
6.8.1 General
To determine the efficiency at a load corresponding to 30 % of the nominal heat output, or the
arithmetic mean of the maximum and minimum heat output for range-rated boilers, one of the
following methods shall be
...
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