SIST EN 13203-1:2025

SLOVENSKI STANDARD
01-september-2025
Nadomešča:
SIST EN 13203-1:2015
Plinske gospodinjske naprave za pripravo tople sanitarne vode - 1. del:
Ocenjevanje zmogljivosti priprave tople vode
Gas fired domestic appliances producing hot water - Part 1: Assessment of performance
of hot water deliveries
Gasbeheizte Geräte für die sanitäre Warmwasserbereitung für den Hausgebrauch - Teil
1: Bewertung der Leistung der Warmwasserbereitung
Appareils domestiques produisant de l'eau chaude sanitaire utilisant les combustibles
gazeux - Partie 1 : Évaluation de la performance en puisage d'eau chaude
Ta slovenski standard je istoveten z: EN 13203-1:2025
ICS:
91.140.65 Oprema za ogrevanje vode Water heating equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 13203-1
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2025
EUROPÄISCHE NORM
ICS 91.140.65 Supersedes EN 13203-1:2015
English Version
Gas fired domestic appliances producing hot water - Part
1: Assessment of performance of hot water deliveries
Appareils domestiques produisant de l'eau chaude Gasbeheizte Geräte für die sanitäre
sanitaire utilisant les combustibles gazeux - Partie 1 : Warmwasserbereitung für den Hausgebrauch - Teil 1:
Évaluation de la performance en puisage d'eau chaude Bewertung der Leistung der Warmwasserbereitung
This European Standard was approved by CEN on 4 May 2025.

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, Türkiye 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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 13203-1:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 General test conditions . 7
4.1 Reference conditions . 7
4.2 Measurement uncertainties . 7
4.3 Test conditions . 8
4.3.1 General . 8
4.3.2 Test room . 8
4.3.3 Water supply . 8
4.3.4 Steady-state . 8
4.3.5 Initial adjustment of the appliance . 8
4.3.6 Initial state conditions . 9
4.3.7 Electrical supply . 9
5 Characterization of the domestic hot water function of appliances . 9
5.1 General . 9
5.2 Characterization according to the domestic hot water flow rates . 9
5.2.1 Specific flow rate . 9
5.2.2 Tapping capability . 10
5.2.3 Classification according to the quantity of available domestic hot water . 11
5.3 Classification according to the quality of the domestic hot water produced . 12
5.3.1 Classification procedure . 12
5.3.2 Test for classification according to the performance in delivery of domestic hot
water production . 13
6 Information . 16
7 Calculation of V40 - Mixed water at 40 °C (V40) . 16
Annex A (informative)  Test conditions . 17
Annex B (informative)  Test rig and measurement devices . 30
B.1 General . 30
B.2 Pressure measurement . 31
B.3 Temperature measurement . 31
Annex ZA (informative) Relationship between this European Standard and the ecodesign
requirements of Commission Regulation (EU) n° 814/2013 [OJEU L239 of 6
September 2013] aimed to be covered . 34
Bibliography . 35

European foreword
This document (EN 13203-1:2025) has been prepared by Technical Committee CEN/TC 109 “Central
heating boilers using gaseous fuels”, the secretariat of which is held by NEN.
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 2025, and conflicting national standards shall
be withdrawn at the latest by December 2025.
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 13203-1:2015.
The changes in this revision were oriented to align, when relevant, the requirements and tests between
instantaneous appliance and appliances with a storage tank. The main changes are the following:
— editorial improvement (definitions, tapping capacity, …);
— alignment of some Figures with the revised text;
— reference conditions (4.1) aligned to EN 13203-2:2022;
— tests for classification of the appliance on domestic water production (5.3.2 - classification, 5.3.2.7 –
temperature fluctuation).
This document has been prepared under a standardization request addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
For the relationship with EU Legislation, see informative Annex ZA, which is an integral part of this
document.
NOTE Useful standards are EN 26, EN 15502-1, EN 15502-2-1 and EN 15502-2-2 (see the Bibliography).
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website. 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, Türkiye and the United Kingdom.
1 Scope
This document is applicable to gas-fired appliances producing domestic hot water. It applies to both
instantaneous and storage appliances; water-heaters and combination boilers that have:
— heat input not exceeding 70 kW; and
— hot water storage capacity (if any) not exceeding 500 l.
A combination boiler can be fitted with a storage tank or not. The domestic hot water production can be
integrated or coupled. The product is considered as a single appliance.
This document specifies in qualitative and quantitative terms the performance in delivery of domestic
hot water for a selected variety of uses. It also gives a system for presenting the information to the user.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp/
3.1
control cycle
time cycle for keeping components and/or the hot storage water tank (if any) of the domestic hot water
circuit at predetermined temperature level, consists of an «ON» duration time during which the heating
of the domestic hot water (by gas energy and electric auxiliary energy) is operating, and an «OFF»
duration time during which no heating occurs
3.2
domestic water mean temperature (T )
m
average temperature of the water delivered during the time Δt
T ∫T ×dt
m
∆t
3.3
domestic water test temperature
temperature of the delivered water at which the tests are conducted
3.4
storage tank
reservoir for domestic hot water
=
3.5
kitchen specific flow rate (D )
c
domestic hot water flow rate corresponding to a mean temperature rise of 45 K that the appliance can
supply
Note 1 to entry: Dc is expressed in litre per minute (l/min).
3.6
minimum declared water flow rate (D )
m
lowest domestic hot water flow rate stated by the manufacturer maintaining a stable temperature
Note 1 to entry: D is expressed in litre per minute (l/min).
m
3.7
nominal domestic hot water heat input (Q )
nw
value of the heat input stated by the manufacturer for the production of domestic hot water
Note 1 to entry: Qnw is expressed in kilowatt (kW).
3.8
overall performance factor (F)
numerical value used to quantify the overall performance associated with domestic hot water use,
corresponding to the sum of the products of the particular performance factors multiplied by the
weighting coefficients
n
F af ×
∑
ii
i=1
3.9
particular performance factor (f )
i
numerical value which quantifies each of the performance criteria
Note 1 to entry: each performance criteria are listed in Table 1
3.10
specific flow rate (D)
domestic hot water flow rate declared by the manufacturer corresponding to a mean temperature rise of
30 K that the appliance can supply in two successive delivery periods
Note 1 to entry: D is expressed in litre per minute (l/min).
3.11
summer mode
conditions during which the appliance supplies energy only for the production of domestic hot water
3.12
tapping capability (R)
hot water delivery flow rate, as stated by the technical documentation, at which water can be drawn off
for a specified time or times with a predetermined temperature rise
Note 1 to entry: the specified times can be 5 min; 10 min; 20 min or continuous.
Note 2 to entry: R is expressed in litre per minute (l/min).
=
3.13
temperature fluctuation at a constant water flow rate (ΔT )
difference between the minimum and maximum water temperatures that can occur during delivery at a
constant water flow rate with a constant inlet temperature
Note 1 to entry: ΔT2 is expressed in Kelvin (K)
3.14
temperature fluctuation between successive deliveries (ΔT )
maximum domestic hot water temperature difference between successive deliveries
Note 1 to entry: ΔT is expressed in Kelvin (K)
3.15
temperature stabilization time following a variation of the water flow rate (t )
s
time taken to obtain a predetermined fluctuation, following a rapid variation of the water flow rate
Note 1 to entry: ts is expressed in second (s)
3.16
temperature variation according to water flow rate (ΔT )
variation of the mean hot water temperature consequent upon variations of the water flow rate
Note 1 to entry: ΔT1 is expressed in Kelvin (K)
3.17
waiting time (t )
m
time taken to reach, at appliance outlet, 90 % of the domestic hot water temperature rise of 45 K without
subsequently falling below 34 K
Note 1 to entry: t is expressed in second (s)
m
3.18
weighting coefficient (a )
i
numerical coefficient used to quantify the importance given to each particular performance factor in
connection with the use of domestic hot water
3.19
rapid response thermometer
measuring instrument with a response time such that 90 % of the final temperature rise, from 15 °C to
100 °C, is obtained within about 1 s, when the sensor is plunged into still water
3.20
electric auxiliary energy
electric energy consumed by the system components such as pump, fan, valves, heating elements and
control unit that enables the heat generator‘s designed operation
4 General test conditions
4.1 Reference conditions
Unless otherwise stated, the general test conditions are as follows:
— cold water temperature: 10 °C;
— range over the whole duration of the test: (8 °C to 12 °C);
— cold water pressure: 2 bar;
— ambient air temperature: 20 °C;
— range over the whole duration of the test: (18 °C to 22 °C);
— electrical supply voltage: (230 ± 2) V (single phase).
4.2 Measurement uncertainties
Except where otherwise stated in the clauses describing the tests, the uncertainties of measurements
carried out shall not be greater than the maximum uncertainties indicated below.
The standard deviations take account the various sources of uncertainty: contribution from the
instrument, repeatability, calibration, ambient conditions, etc.
— water flow rate: ± 1 %;
— gas rate: ± 1 %;
— time: ± 0,2 s;
— temperatures:
— ambient: ± 1 K;
— water: ± 0,5 K;
— gas: ± 0,5 K;
— mass: ± 0, 5 %;
— gas pressure: ± 1 %;
— gas calorific value: ± 1 %;
— gas density: ± 0,5 %;
— electrical energy: ± 2 %.
The stated measurement uncertainties relate to individual measurements. For measurements that
combine a number of individual measurements, smaller uncertainties on the individual measurements
may be necessary to ensure a total uncertainty within ± 2 % under the steady-state conditions.
These uncertainties correspond to two standard deviations (2σ).
4.3 Test conditions
4.3.1 General
Except where otherwise stated, the appliance shall be tested under the following conditions.
Some examples of measurement profiles as a purely informative indication are given in Annex A
(informative).
Information on test rig and measurement devices are given in Annex B (informative).
4.3.2 Test room
The appliance shall be installed in a well-ventilated, draught-free room (air speed less than 0,5 m/s).
The appliance shall be protected from direct solar radiation and radiation from heat generators.
4.3.3 Water supply
For the tests:
— domestic water pressure is the static inlet pressure under dynamic conditions measured as close as
possible to the appliance;
— inlet and outlet temperatures of the domestic water shall be measured in the centre of the flow and
as close as possible to the appliance.
The inlet temperatures shall be measured immediately upstream of the water inlet connection. Except
where otherwise stated, the outlet temperatures shall be measured immediately downstream of the
outlet connection or, in the case of an appliance with spout delivery, by means of an immersed
temperature measuring device, e.g. a u-tube fitted at the outlet of a tube of the same length as the
minimum length of the spout normally supplied by the manufacturer.
The hot water temperature shall be measured with a rapid response thermometer (see 3.19).
4.3.4 Steady-state
Steady-state operating conditions shall be regarded as established when the appliance operates for
sufficient time to reach thermal stabilization. The steady-state is reached when the water temperature at
the outlet does not vary by more than ± 0,5 K.
NOTE This condition can be reached with a gas which is different from the specified test gas, provided that
appliance is supplied with the specified test gas at least 5 min before the requirements are verified.
4.3.5 Initial adjustment of the appliance
The appliance shall be installed in accordance with the manufacturer's instructions.
The heat input shall be adjusted to within ± 2 % of the nominal domestic hot water heat input.
The delivered water temperature at the appliance outlet is specified as follows (see Figures A.1 and A.2):
a) appliances with an adjustable temperature: the tests shall be carried out at a temperature not greater
than 65 °C, with a minimum temperature increase equal to or greater than 45 K above water inlet
temperature.
b) appliances with a fixed temperature: the tests shall be carried out at the temperature specified by
the manufacturer, with a minimum temperature increase equal to or greater than 45 K.
The same conditions of initial adjustment stated in the appliance documentation shall be used for all the
tests.
These conditions shall be included in the test report.
4.3.6 Initial state conditions
All the tests of this standard shall be conducted as follows (see Figures A.3 and A.4):
— when there is no control cycle to consider: with exception of test of 5.3.2.7, at least 1h after the
previous delivery;
— when there is a control cycle to consider: after a time corresponding to 20 % (but not exceeding 1h)
of the “OFF” time of the burner or circulators if any. The time (t ) is taken from the time the burner
a
or circulators if any turns off in the control cycle.
The same initial state conditions shall be used for all the tests. These conditions shall be included in the
test report.
For appliances with a central heating function, tests shall be conducted in summer mode.
4.3.7 Electrical supply
The appliance shall be supplied with the nominal voltage or a voltage included within the range of
nominal voltages stated in the installation instructions.
5 Characterization of the domestic hot water function of appliances
5.1 General
The domestic hot water function shall be characterized in two different ways:
— firstly, according to the domestic hot water specific flow rates, the tapping capability and the
corresponding uses (see 5.2);
— secondly, according to the quality of the domestic hot water produced (see 5.3); obtaining a number
of stars corresponding to a determined level of performance.
5.2 Characterization according to the domestic hot water flow rates
5.2.1 Specific flow rate
5.2.1.1 Test requirement
The measured value of the specific flow rate shall be not lower than 95 % of that stated by the appliance
documentation.
5.2.1.2 Test
The appliance shall be adjusted to deliver hot water at the flow rate stipulated by the installation
instructions for this test.
The pressure loss across the appliance shall not exceed 2 bar.
During the measurement of the specific flow rate, the minimum temperature increase shall be equal to or
greater than 30 K.
Before the test, the appliance shall be adjusted in accordance with 4.3.5. A first delivery shall be carried
out over a period of 10 min, followed by 20 min with no delivery and then by a second delivery over a
period of 10 min (see Figures A.5 and A.6).
Measurements of temperature and flow rate shall be made and recorded, at intervals not exceeding 2 s.
A plot of temperature against time is made to obtain the mean water temperature rise during each
delivery.
For each delivery the following shall be calculated by the formula:
m
i ∆T
(10)
D × (1)
i
10 30
where
D is the calculated flow rate for each delivery; D and D are determined respectively during
i 1 2
the first and second deliveries, in litre per minute (l/min);
m is the quantity of water collected during the first or second delivery with a minimum
i(10)
temperature rise of 30 K, in litre (l);
ΔT is the mean temperature rise of the collected water, in Kelvins (K) during the first and
second deliveries.
If the difference between D and D does not exceed numerically 10 % of their average value then
1 2
D + D
D = (2)
where D is the determined specific flow rate.
If the difference between D and D exceeds numerically 10 % of their average value, then D is the lower
1 2
value.
The kitchen specific flow rate (D ) shall be calculated by the formula:
c
DD × (3)
C
NOTE When the water temperature is adjustable, additional measurement of the specific flow rate with a
delivery temperature can be specified by the appliance documentation.
5.2.2 Tapping capability
5.2.2.1 Test requirement
The appliance shall be capable of delivering water at the flow rate stated in the appliance documentation
with a temperature rise of 30 K, for the standard time of 10 min and continuously.
NOTE For appliances without storage tank, if the value stated by the technical instructions for the continuous
flow rate is the same stipulated for specific flow rate, the data of the specific flow rate test could be used (see 5.2.1.2).
The tapping capability corresponding to these time periods shall be available to the consumer.
5.2.2.2 Test
The appliance shall be adjusted to deliver water at the flow rate and temperature to be stated by the
appliance documentation for this test.
The pressure loss across the appliance shall not exceed 2 bar.
Before starting the t
...