IEC 60379:2023

IEC 60379 ®
Edition 4.0 2023-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Methods for measuring the performance of electric storage water heaters for
household purposes
Méthodes de mesure de l'aptitude à la fonction des chauffe-eau électriques à
accumulation à usages domestiques

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IEC 60379 ®
Edition 4.0 2023-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Methods for measuring the performance of electric storage water heaters for

household purposes
Méthodes de mesure de l'aptitude à la fonction des chauffe-eau électriques à

accumulation à usages domestiques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 91.140.65 ISBN 978-2-8322-6439-3

– 2 – IEC 60379:2023 © IEC 2023
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols and units . 9
5 Calculation of the electrical energy efficiency (η ) . 10
elecwh
6 Measured parameters . 10
7 General conditions for measurements . 10
8 Reference conditions . 12
9 Test procedures . 15
9.1 Standard test procedure. 15
9.1.1 General . 15
9.1.2 Installation . 15
9.1.3 Stabilisation . 15
9.1.4 Storage volume . 16
9.1.5 Filling and heat-up . 16
9.1.6 Stabilisation at zero-load and cyclic temperature variation (differential) . 17
9.1.7 Tapping . 17
9.1.8 Reporting of Q . 18
elec
9.1.9 Re-stabilisation at zero-load . 18
9.1.10 Mixed water quantity delivered at 40 °C . 18
9.2 Smart control test procedure . 20
9.2.1 Measurement procedure . 20
9.2.2 Installation . 20
9.2.3 Stabilisation . 20
9.2.4 Filling and heat-up . 20
9.2.5 Stabilisation before reference period . 21
9.2.6 Reference period . 21
9.2.7 Smart period . 22
9.2.8 Reporting of the smart control factor . 23
9.2.9 WHL control cycle . 23
9.3 Measurement of stored water temperatures . 23
9.4 Thermostat setting . 24
9.5 Standing loss per 24 h . 25
9.5.1 General . 25
9.5.2 Single-tank standing loss . 25
9.5.3 Multi-tank standing loss for directly measurable products . 25
9.5.4 Multi-tank standing loss for not directly measurable products . 27
9.6 Hot water output . 29
9.7 Maximum hot water output . 29
10 Data report . 30
Annex A (normative) Calculation of the specific energy efficiency and of the annual
consumption of electric energy . 32
A.1 Symbols and units . 32
A.2 Calculation of the specific energy efficiency . 32

A.3 Calculation of the annual consumption of electric energy . 33
A.4 Data report . 33
Annex B (normative) Test setup . 34

Figure 1 – Test procedure for "energized appliances" . 15
Figure 2 – Test procedure for "off-peak appliances" . 15
Figure 3 – Test procedure for "smart cycle" . 20
Figure 4 – Assembly scheme . 27
Figure 5 – Assembly scheme BENCH . 28
Figure B.1 – Schematic representation of storage water-heaters. 35
Figure B.2 – Position of the thermocouples for vertical and horizontal models . 36
Figure B.3 – Example of hydraulic connection (unvented products) . 37
Figure B.4 – Schemes for directly measurable multi-tank appliances . 38
Figure B.5 – Directly measurable multi tank . 39
Figure B.6 – Not directly measurable multi tank . 39

Table 1 – Electricity . 11
Table 2 – Test conditions, outputs, set values and tolerances. . 11
Table 3 – Load profile of the water heater (reference test tapping patterns) . 13
Table 4 – Tolerance of the rated storage volume . 16
Table 5 – Tapping profiles . 21
Table 6 – Rated capacity and flow rates . 29
Table 7 – Data report . 31
Table A.8 – k values . 33
Table A.9 – Complements to data report . 33
Table B.1 – Thickness of insulation according to size of pipe or connection . 40

– 4 – IEC 60379:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
METHODS FOR MEASURING THE PERFORMANCE
OF ELECTRIC STORAGE WATER HEATERS
FOR HOUSEHOLD PURPOSES
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 60379 has been prepared by subcommittee SC59C: Electrical heating appliances for
household and similar purposes, of IEC technical committee 59: Performance of household and
similar electrical appliances. It is an International Standard.
This fourth edition cancels and replaces the third edition published in 1987. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) sustainable development aspects of EU legislation are taken into account, including features
such as smart control, V modification and measuring procedures for multi-tank appliances.
The text of this International Standard is based on the following documents:
Draft Report on voting
59C/282/FDIS 59C/285/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC 60379:2023 © IEC 2023
METHODS FOR MEASURING THE PERFORMANCE
OF ELECTRIC STORAGE WATER HEATERS
FOR HOUSEHOLD PURPOSES
1 Scope
This document specifies methods for measuring the performance of electric storage water
heaters to produce domestic potable or non-potable hot water for household and similar use.
The object is to state and define the principal performance characteristics of electric storage
water heaters and to describe the test methods for measuring these characteristics.
NOTE 1 This document does not apply to:
• storage water heaters that use electricity as a secondary source of heating the water;
• storage water heaters that do not use a tank to store hot water;
• electric storage water heaters that do not meet the minimum (or maximum) output performance of the smallest
(or biggest) load profile, as defined in Table 3;
• water-heaters without thermal insulation.
NOTE 2 This document does not specify safety requirements. For safety requirements, see IEC 60335-1 in
conjunction with IEC 60335-2-21.
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
storage water heater
water heater that uses electric heating elements as the means of heating water for long-term
storage in a thermally insulated container and provided with a device to control the water
temperature
3.2
primary function
production of hot water for household and similar needs
3.3
energized storage water heater
storage water heater that is designed to supply hot water and be energized for 24 h per day

3.4
off-peak storage water heater
storage water heater that is designed to supply hot water and configured or installed, whilst
only being supplied with electrical energy at off-peak/low-tariff periods
Note 1 to entry: The off-peak storage water heater is required to fulfil the requirements of the tapping pattern
between 7:00 h and 22:00 h without external energy supply, e.g. to enable operation at off-peak/low-tariff periods
and/or to operate in conditions of insecurity of energy supply. A product qualifies as "off-peak" if it is only energized
for a maximum of 8 consecutive hours anywhere between 22:00 h and 7:00 h during the test with the 24h load profile.
3.5
load profile
output performance (in terms of flowrates, temperatures, tapping pattern, etc.) of a storage
water heater when fulfilling its primary function under specific ambient conditions (see Table 2
and Table 3), as declared by the manufacturer
3.6
energy efficiency
ratio between the delivered energy in the domestic potable or non-potable hot water for its load
profile and the consumed electrical energy
3.7
storage volume
rated quantity of water stored in the appliance
3.8
smart control
device that automatically adapts the water heating process to individual usage conditions with
the aim of reducing energy consumption
3.9
out-of-the-box mode
standard operating condition, setting or mode set by the manufacturer at factory level, to be
active immediately after the appliance's installation, suitable for normal use by the end-user
according to the water tapping pattern for which the product has been designed and placed on
the market
3.10
closed water heater
unvented storage water heater intended to operate at the pressure of the water system, the
flow of water being controlled by one or more valves in the outlet system
3.11
cistern-fed water heater
water heater supplied from a cistern in which the flow of water is controlled by one or more
valves in the outlet system, and which is provided with a vent open to the atmosphere and so
arranged that the expanded water can return to the feed cistern
3.12
open outlet water heater
water heater in which the flow of water is controlled by a valve in the inlet pipe and so arranged
that the expanded water can overflow through the outlet pipe
3.13
vented water heater
water heater open to the atmosphere, so that under no condition of use can the pressure at the
surface of the water be other than atmospheric

– 8 – IEC 60379:2023 © IEC 2023
3.14
cistern-type water heater
cistern-fed water heater which has a feed cistern as an integral part of the appliance
3.15
multi-tank water heater
water heater with two or more hydraulic connected containers, designed to have the possibility
to work independently in terms of working temperature and/or pressure condition
Note 1 to entry: A multi-tank product has to be defined as directly measurable if it is possible to measure the
temperature (immersed or welded sensors) of all the dome tanks without compromising the product's performances,
otherwise the product has to be classified as not directly measurable. Based on that definition for the dome tanks'
temperature measurement, the multi-tank products are defined as:
• directly measurable, or
• not directly measurable.
3.16
rated capacity
assigned water capacity of the water heater, and marked on it, by the manufacturer
3.17
standing loss per 24 h
energy-consumption of a filled water-heater, after steady-state conditions have been reached,
when connected to the electrical supply, during any 24 h duration when no water is withdrawn
3.18
rated voltage
voltage (for three phase-supply, the voltage between phases) assigned to the appliance by the
manufacturer
3.19
V
40Ref
mixed water quantity delivered at 40 °C with 65 °C storage temperature and 15 °C cold water
inlet temperature
3.20
V
40max
mixed water quantity delivered at 40 °C with maximum storage temperature setting and 15 °C
cold water inlet temperature with heating elements powered on
Note 1 to entry: Maximum rated power of the appliance.
3.21
V
mixed water quantity delivered at 40 °C with out-of-the-box mode temperature setting and 10 °C
cold water inlet temperature
3.22
smart control factor
SCF
factor describing the water heating energy efficiency gain due to smart control
Note 1 to entry: The value is between SCF = 0 and SCF = 1.
3.23
energy-related product
ErP
product that uses energy, or that does not use energy, but has an impact on energy consumption

3.24
conversion coefficient
CC
factor to indicate how much primary energy is used to generate a unit of electricity
3.25
declared load profile
load profile declared by the manufacturer for the appliance
4 Symbols and units
Symbol Unit Description
η Electric energy efficiency of a storage water heater.
[%]
elecwh
Q Reference energy for the 24 h tapping pattern for the load profile of the water
ref
[kWh]
heater.
Q Electricity consumption with the relevant 24 h tapping pattern.
[kWh]
elec
Ambient temperature during the tests
θ
[°C]
amb
θ´ Mean water temperature for the determination of θ , measured at the outlet
[°C]
p p
Mean water temperature without withdraw from the tank
θ
[°C]
M
f Minimum flow rate at which hot water is contributing to the reference energy as
[l/min]
specified in Table 3.
T Water temperature at which hot water starts contributing to the reference energy as
m
[°C]
specified in Table 3
T Minimum water temperature to be achieved during water draw off as specified in
p
[°C]
Table 3
T
Set-point temperature
[°C]
set
t Reheating time for a water temperature rise of 50 K

R,50
Q Measured electricity consumption over 24 h test (step 4 of Figure 1 and Figure 2).
[kWh]
testelec
Q Useful energy content of the hot water of n draw-offs
[kWh]
H2O
Sum of quantity of hot water totally delivered during the tapping period.
full-drawing
[l]
V
water
V Measured volume delivered at the mean water temperature.
[l]
40_exp
V Mixed water quantity delivered at 40 °C.
[l]
V mixed water quantity delivered at 40 °C with 65 °C storage temperature and 15°C
40Ref
[l]
cold water inlet temperature
V Mixed water quantity delivered at 40 °C with maximum temperature setting and
40max
[l]
heating elements powered on
C Rated capacity of water heater (given by manufacturer)
[l]
R
C Actual capacity of water heater
[l]
act
m Actual weight of water contained inside the tank of the Water Heater
[kg]
act
m Number of tanks (containers) of the appliance
θ Mean water temperature calculated as average of the j-tank for the first thermostat
A1tanks
[°C]
cut-out
θ Mean water temperature calculated as average of j-tank for the last (n) thermostat
Antanks
[°C]
cut-out
θ Mean water temperature without withdraw of the j-tank
[°C]
Mj
θ Mean water temperature without withdraw of all the tanks
[°C]
M_mt
θ Measured water temperature after a thermostat cut-out for the j-tank
[°C]
Aij
– 10 – IEC 60379:2023 © IEC 2023
Symbol Unit Description
θ Mean water temperature after a thermostat cut-out for the j-tank
[°C]
Aj
θ Measured water temperature after a thermostat cut-in for the j-tank
[°C]
Eij
θ Mean water temperature after a thermostat cut-in for the j-tank
[°C]
Ej
Measured temperature in the upper section of the tank
θ
[°C]
up
smart Presence or not of smart control (value shall be 0 or 1).
SCF Efficiency gain by smart control function.

5 Calculation of the electrical energy efficiency (η )
elecwh
The electrical energy efficiency (η ) of a storage water heater is the ratio between the
elecwh
delivered energy in the hot water for the tapping pattern of its load profile and the consumed
energy. The consumed energy is the result of the test of the water heater with adjustments for:
• smart control that can reduce the energy consumption
The electrical energy efficiency of a storage water heater shall be calculated with Formula (1):
Q
ref
η =
(1)
elecwh
Q 1−⋅SCF smart
( )
elec
where:
Q is the delivered energy for the 24 h tapping pattern for the load profile of the water
ref
heater, in kWh;
Q is the consumption of electric energy with the relevant 24 h tapping pattern, in kWh;
elec
smart indicates the presence of smart control and is yes = 1, no = 0;
SCF factor for efficiency gain by smart control function.
NOTE SCF=0 in case no smart control is detected during testing (see 9.2).
6 Measured parameters
The parameters below shall be established following the measurement methods described in
Clause 7 and Clause 9:
1) Q electricity consumption [kWh/d]
elec
2) Ƞ electrical energy efficiency [%]
elecwh
3) C storage volume [l]
act
7 General conditions for measurements
Measurements shall be carried out with an electrical supply satisfying the characteristics
outlined in Table 1.
Table 1 – Electricity
Measured quantity Unit Value Permissible Uncertainty of Notes
deviation measurement
(average over (accuracy)
test period)
Electricity
Power W  ±2 %
energy kWh  ±2 %
voltage V Rated value ±2 % ±0,5 %
electric current A  ±0,5 %
frequency Hz Rated value ±1 %

Table 2 gives additional test conditions and tolerances for test outputs (i.e. thermal energy).
Table 2 – Test conditions, outputs, set values and tolerances.
Permissible
Permissible
deviations of Uncertainty of
deviation
Measured quantity Unit Value individual measurement Notes
(average over
measured (accuracy)
test period)
values
Time
Time s  ±0,1 s
Maximum interval s 3
between samples
(during the delivery of
hot water)
Maximum interval s 60
between samples
(during the non-deliver
of hot water)
Domestic potable or
non-potable water
Cold water °C/ K 10 °C ±1 K ±1 K ±0,5 K
temperature for 9.1.5
to 9.2
Cold water °C/ K 15 °C ±1 K ±1 K ±0,5 K
temperature for 9.3 to
9.7
Cold-water pressure MPa 0,3 MPa  ± 5 %
a, b
Hot-water temperature °C/ K pattern  ±0,5 K

Volume flowrate l / min pattern  ≥ 5 l/min: ±1%
< 5l/min:
±0,05 l/min
Volume measurements l  ± 0,5 %
c
Thermal energy kWh pattern ≥ 0,5 kWh: ≥ 0,5 kWh: ±2 % ≥ 0,5 kWh: ±2 %

±2 %
< 0,5 kWh: < 0,5 kWh:10 Wh
< 0,5 kWh: 10 Wh
10 Wh
– 12 – IEC 60379:2023 © IEC 2023
Permissible
Permissible
deviations of Uncertainty of
deviation
Measured quantity Unit Value individual measurement Notes
(average over
measured (accuracy)
test period)
values
Ambient air
Temperature °C/K 20 °C ±1 K ±1 K
d
Humidity % < 85
a
To be measured with a "rapid response thermometer", meaning an instrument that registers within 1 s at least
90 % of the final temperature rise from 15 °C to 100 °C when the sensor is plunged in still water.
b
Thermocouple with a maximum diameter of 0,5 mm, centred in stream, directly at outlet.
c
Apart from the maximum deviation, a correction factor Q /Q is applied, whereby Q is taken from Table 3
ref H2O ref
and Q is the energy content of the useful water actually delivered during the test. "Useful water" is water
H2O
with a temperature higher than a threshold value T for tappings in a profile specified in Table 3.
m
d
The values for temperature and relative humidity are only valid at steady-state conditions and not at the moment
when hot water is withdrawn from the water heater.

All other installation requirements are carried out in accordance with the manufacturer's
instructions. All pipe connections of the test setup shall be thermally insulated, in accordance
with the values given in Table B.1.
8 Reference conditions
Table 3 specifies the tapping patterns for the chosen load profile. Parameters in the table are:
a) load profile [XXS-4XL, in header row of table];
b) h: hour [hh:mm] starting at 0:00 h;
c) Q [kWh]: useful energy content of water withdrawal to be achieved in the draw-off;
tap
d) f [l/min]: minimum flow rate to be reached during tapping;
e) T [°C]: temperature from which counting of useful energy content starts;
m
f) T [°C]: minimum (peak) temperature to be achieved during tapping;
p
g) Q [kWh/d]: daily (24 h) useful energy content of all water draw-offs, effectively the sum of
ref
all Q .
tap
As much as possible, the test method uses a 'black-box' approach, i.e. largely technology-
independent. This means, among other things, that the laboratory uses the original appliance
thermostat, in the out-of-the-box mode.

Table 3 – Load profile of the water heater (reference test tapping patterns)
XXS XS S  M L XL  XXL 3XL 4XL
Q T T Q T T Q T T Q T T Q T T Q T T Q T T Q T T Q T T
tap f m p tap f m p tap f m p tap f m p tap f m p tap f m p tap f m p tap f m p tap f m p
l/mi
h kWh l/min ºC ºC kWh l/min ºC ºC kWh l/min ºC ºC h kWh l/min ºC ºC kWh l/min ºC ºC kWh l/min ºC ºC h kWh l/min ºC ºC kWh l/min ºC ºC kWh ºC ºC
n
07.00 0, 105 2 25   0,105 3 25  07.00 0,105 3 25 0,105 3 25 0,105 3 25  07.00 0,105 3 25 11,2 48 40  22,4 96 40
07.05        07.05 1,400 6 40 1,400 6 40    07.05
07.15        07.15     1,820 6 40  07.15 1,820 6 40
07.26       07.26     0,105 3 25  07.26 0,105 3 25
07.30 0, 105 2 25 0,525 3 35 - 0,105 3 25  07.30 0,105 3 25 0,105 3 25    07.30
07.45       07.45   0,105 3 25 4,420 10 10 40 07.45 6,240 16 10 40
08.01        08.01 0,105 3 25   0,105 3 25  08.01 0,105 3 25 5,04 24 25  10,08 48 25
08.05       08.05   3,605 10 10 40   08.05
08.15       08.15 0,105 3 25   0,105 3 25  08.15 0,105 3 25
08.25       08.25   0,105 3 25    08.25
08.30 0, 105 2 25   0,105 3 25  08.30 0,105 3 25 0,105 3 25 0,105 3 25  08.30 0,105 3 25
08.45       08.45 0,105 3 25 0,105 3 25 0,105 3 25  08.45 0,105 3 25
09.00       09.00 0,105 3 25 0,105 3 25 0,105 3 25  09.00 0,105 3 25 1,68 24 25  3,36 48 25
09.30 0, 105 2 25   0,105 3 25  09.30 0,105 3 25 0,105 3 25 0,105 3 25  09.30 0,105 3 25
10.00       10.00     0,105 3 25  10.00 0,105 3 25
10.30       10.30 0,105 3 10 40 0,105 3 10 40 0,105 3 10 40 10.30 0,105 3 10 40 0,84 24 10 40 1,68 48 10 40
11.00       11.00     0,105 3 25  11.00 0,105 3 25
11.30 0, 105 2 25   0,105 3 25  11.30 0,105 3 25 0,105 3 25 0,105 3 25  11.30 0,105 3 25
11.45 0, 105 2 25   0,105 3 25  11.45 0,105 3 25 0,105 3 25 0,105 3 25  11.45 0,105 3 25 1,68 24 25  3,36 48 25
12.00 0, 105 2 25      12.00       12.00
12.30 0, 105 2 25      12.30       12.30
12.45 0,105 2 25 0,525 3 35 - 0,315 4 10 55 12.45 0,315 4 10 55 0,315 4 10 55 0,735 4 10 55 12.45 0,735 4 10 55 2,52 32 10 55 5,04 64 10 55
14.30       14.30 0,105 3 25 0,105 3 25 0,105 3 25  14.30 0,105 3 25
15.00       15.00     0,105 3 25  15.00 0,105 3 25
15.30        15.30 0,105 3 25 0,105 3 25 0,105 3 25  15.30 0,105 3 25 2,52 24 25  5,04 48 25
16.00       16.00     0,105 3 25  16.00 0,105 3 25
16.30        16.30 0,105 3 25 0,105 3 25 0,105 3 25  16.30 0,105 3 25
17.00       17.00     0,105 3 25  17.00 0,105 3 25

– 14 – IEC 60379:2023 © IEC 2023

XXS XS S  M L XL  XXL 3XL 4XL
Q T T Q T T Q T T Q T T Q T T Q T T Q T T Q T T Q T T
tap f m p tap f m p tap f m p tap f m p tap f m p tap f m p tap f m p tap f m p tap f m p
l/mi
h kWh l/min ºC ºC kWh l/min ºC ºC kWh l/min ºC ºC h kWh l/min ºC ºC kWh l/min ºC ºC kWh l/min ºC ºC h kWh l/min ºC ºC kWh l/min ºC ºC kWh ºC ºC
n
18.00 0, 105 2 25   0,105 3 25  18.00 0,105 3 25 0,105 3 25 0,105 3 25  18.00 0,105 3 25
18.15 0, 105 2 25   0,105 3 40  18.15 0,105 3 40 0,105 3 40 0,105 3 40  18.15 0,105 3 40
18.30 0, 105 2 25      18.30 0,105 3 40 0,105 3 40 0,105 3 40  18.30 0,105 3 40 3,36 24 25  6,72 48 25
19.00 0, 105 2 25      19.00 0,105 3 25 0,105 3 25 0,105 3 25  19.00 0,105 3 25
19.30 0, 105 2 25      19.30       19.30
20.00 0, 105 2 25      20.00       20.00
20.30   1,050 3 35 - 0,420 4 10 55 20.30 0,735 4 10 55 0,735 4 10 55 0,735 4 10 55 20.30 0,735 4 10 55 5,88 32 10 55 11,76 64 10 55
20.45 0, 105 2 25      20.45       20.45
20.46       20.46     4,420 10 10 40 20.46 6,240 16 10 40
21.00 0, 105 2 25      21.00   3,605 10 10 40   21.00
21.15 0, 105 2 25      21.15 0,105 3 25   0,105 3 25  21.15 0,105 3 25
21.30     0,525 5 45  21.30 1,400 6 40 0,105 3 25 4,420 10 10 40 21.30 6,240 16 10 40 12,04 48 40  24,08 96 40
21.35 0,105 2 25      21.35       21.35
21.45 0, 105 2 25      21.45       21.45
Qref 2,100  2,100  2,100   Qref 5,845  11,655  19,070  Qref 24,530  46,760  93,520

9 Test procedures
9.1 Standard test procedure
9.1.1 General
Subclauses 9.1.2 to 9.1.10 describe the test procedure to establish the electricity consumption
Q during a 24 h test. The different types of water heaters are described in Annex B
elec
(Figure B.1).
9.1.2 Installation
Install the product in the test environment in accordance with the manufacturer's instructions.
Designated floor-standing appliances are to be placed on a floor with low thermal leakage (e.g.
20 mm-thick medium density fibreboard can be placed under the test object 100 mm above the
floor of the test room).
Wall-mounted products shall be mounted on a panel at least 150 mm from any structural wall
with a free space of at least 250 mm above and below the product and at least 600 mm to the
sides. Products designated to be built-in shall be mounted in accordance with the
manufacturer's instructions.
Products with declared load profiles 3XL and/or 4XL may be tested on-site, provided test
conditions are equivalent, possibly with correction factors, to the ones referenced here.
9.1.3 Stabilisation
Keep product at ambient conditions (test room) until all parts of the product have reached
ambient conditions ± 5K (at least for 24h).

Figure 1 – Test procedure Figure 2 – Test procedure
for "energized appliances" for "off-peak appliances"

– 16 – IEC 60379:2023 © IEC 2023
9.1.4 Storage volume
Step 0 of Figure 1 and Figure 2: the volume of the tank in a storage electric water heater is
measured as follows.
The empty water heater is to be weighed; the weight of the taps on inlet and/or outlet pipes
and/or tubes shall not change when measuring the filled and empty tank.
Then the storage water heater is filled with cold water at a temperature of 13 °C ± 5 °C in
accordance with the manufacturer's instruction at cold water pressure. The water supply is then
cut off.
The filled water heater is to be weighed.
NOTE Water in the feed cistern of a cistern-fed water heater is excluded from the quantity withdrawn.
The difference of the two weights (m ) is to be converted into the volume in litres.
act
m
act
C =
(2)
act
0,9997
This volume is to be reported in litres to the nearest one-tenth of a litre. The measured value
(actual value) shall be within the tolerance of the rated value stated in Table 4.
Table 4 – Tolerance of the rated storage volume
Storage volume [l] Tolerance
V ≤ 30 −5 % to +10 %
V >30l −5 % to +5 %
9.1.5 Filling and heat-up
Step 1 of Figure 1 and Figure 2: products with storage facilities shall be filled with cold water
(10 ± 2) °C. Filling stops at the applicable cold water pressure (see Table 2).
Step 2 of Figure 1 and Figure 2: the product is energized to reach out-of-the-box mode, e.g. for
storage temperature. The product's own means of control (thermostat) shall be used. The next
stage starts at thermostat cut-out.
is calculated from the following formula
The time required for heating up the water by 50 K, t
R,50
and expressed in hours and minutes:
tt= ×
(3)
R, 50 R
θθ−
RC
Where:
t is the heating time during the first heating up of the water heater during step 2;
R
θ is the measured reference temperature at thermostat cut-out;
R
θ is the measured cold-water temperature at the beginning of step 2.
C
9.1.6 Stabilisation at zero-load and cyclic temperature variation (differential)
Step 3 of Figure 1 and Figure 2: keep the product at normal operating conditions as specified
by the manufacturer without draw-offs during at least 12 h. This stage ends – and next stage
starts – at the first thermostat cut-out after 12 h.
The mean water temperature after a thermostat cut-out θ is the average value of n
A
temperatures θ recorded after each cut-out of the thermostat and is given by:
Ai
n
θ
∑
Ai
(4)
i=1
θ =
A
n
The mean water temperature after a thermostat cut-in θ is the average value of n temperatures
E
θ recorded after each cut-in of the thermostat and is given by:
Ei
n
θ
∑ Ei
(5)
i=1
θ =
E
n
The cyclic temperature variation of the thermostat ∆θ is expressed by the formula:
∆θ = θ – θ
(6)
A E
9.1.7 Tapping
Step 4 of Figure 1 and Figure 2: for the selected load profile, draw-offs are made in accordance
with the specifications of the appropriate 24 h tapping pattern in Table 3. Tapping pattern starts
directly after thermostat cut-out from stabilisation part with the first tapping at 7:00 h time-value
as implied in Table 3. The tapping period ends 24 h later. The required useful energy content
of the hot water is the total Q [in kWh] in Table 3.
ref
During the tapping stage, technical parameters (power, temperature, etc.) are established in
accordance with specifications in Table 3. During draw-offs, the recommended maximum
sample rate is 3 s (see Table 2). Recorded values shall be part of the technical test report.
Electricity consumption over the 24 h test Q [kWh electricity] sha
...