SIST EN 50440:2016

Efficiency of domestic electrical storage water heaters and testing methods

This European Standard specifies methods for measuring the performance of electric storage water
heaters for the production of sanitary 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 standard 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 storage 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 4.
NOTE 2 This standard does not specify performance or safety requirements. For safety requirements see EN 60335-1 in
conjunction with EN 60335-2-21.

Wirkungsgrad von elektrischen Warmwasserspeichern für den Hausgebrauch

Efficacité des chauffe-eau électriques à accumulation

La présente Norme européenne spécifie des méthodes de mesure de l’aptitude à la fonction des chauffe-eau électriques à accumulation pour la production d'eau chaude sanitaire à usage domestique et analogue.
Elle a pour objet de préciser et de définir les principales caractéristiques d’aptitude à la fonction des chauffe-eau électriques à accumulation et de décrire les méthodes d'essai pour la mesure de ces caractéristiques.
NOTE 1 La présente norme ne s'applique pas aux:
-   chauffe-eau à accumulation qui utilisent l'électricité en tant que source secondaire de chauffage de l'eau;
-   chauffe-eau à accumulation qui n'utilisent pas un réservoir de stockage d'eau chaude
-   chauffe-eau électriques à accumulation qui ne répondent pas au rendement minimal (ou maximal) du plus petit (ou plus grand) profil de charge, tel que défini dans le Tableau 4.
NOTE 2 La présente norme ne spécifie pas les exigences en matière d’aptitude à la fonction ou de sécurité. Pour les exigences de sécurité, voir l’EN 60335-1 conjointement avec l'EN 60335-2-21.

Učinkovitost gospodinjskih električnih akumulacijskih grelnikov vode in preskusne metode

Ta evropski standard določa metode za merjenje učinkovitosti električnih akumulacijskih grelnikov vode za pripravo tople vode za gospodinjstva in za podobno uporabo. Namen je navesti in opredeliti glavne značilnosti delovanja električnih akumulacijskih grelnikov vode ter opisati preskusne metode za merjenje teh značilnosti.
OPOMBA 1: Ta standard se ne uporablja za:
– akumulacijske grelnike vode, ki uporabljajo elektriko kot pomožni vir ogrevanja vode;
– akumulacijske grelnike vode, ki ne uporabljajo rezervoarjev za akumulacijo vroče vode;
– električne akumulacijske grelnike vode, ki ne izpolnjujejo minimalne (ali maksimalne) zmogljivosti izhoda najmanjšega (ali največjega) profila obremenitve, kot je opredeljen v preglednici 4.
OPOMBA 2: Ta standard ne določa zahteve glede učinkovitosti ali varnostnih zahtev. Za varnostne zahteve glejte EN 60335-1 v povezavi z EN 60335-2-21.

General Information

• Status: Published
• Public Enquiry End Date: 31-Aug-2014
• Publication Date: 13-Dec-2015
• ICS: 91.140.65 - Water heating equipment
• Technical Committee: FGA - Consumer information related to household electrical appliances
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 02-Dec-2015
• Due Date: 06-Feb-2016
• Completion Date: 14-Dec-2015
• Mandate: M/204 - Water heater and hot water storage appliances
• Ref Project: EN 50440:2015 - Efficiency of domestic electrical storage water heaters and testing methods

Relations

• Amended By: SIST EN 50440:2016/A1:2020 - Efficiency of domestic electrical storage water heaters and testing methods
• Effective Date: 01-Oct-2020

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 50440:2016
01-januar-2016
8þLQNRYLWRVWJRVSRGLQMVNLKHOHNWULþQLKDNXPXODFLMVNLKJUHOQLNRYYRGHLQ
SUHVNXVQHPHWRGH
Efficiency of domestic electrical storage water heaters and testing methods
Wirkungsgrad von elektrischen Warmwasserspeichern für den Hausgebrauch
Efficacité des chauffe-eau électriques à accumulation
Ta slovenski standard je istoveten z: EN 50440:2015
ICS:
91.140.65 Oprema za ogrevanje vode Water heating equipment
SIST EN 50440:2016 en,fr

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

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SIST EN 50440:2016
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SIST EN 50440:2016
EUROPEAN STANDARD EN 50440
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2015
ICS 91.140.65
English Version
Efficiency of domestic electrical storage water heaters and
testing methods

Efficacité des chauffe-eau électriques à accumulation et Effizienz von elektrischen Warmwasserspeichern für den

méthodes associées Hausgebrauch

This European Standard was approved by CENELEC on 2015-10-05. CENELEC 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 CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the

same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

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

Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN 50440:2015 E
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SIST EN 50440:2016
EN 50440:2015 (E)
Content

European foreword ................................................................................................................................. 3

1 Scope ................................................................................................................................................. 4

2 Normative references ....................................................................................................................... 4

3 Terms and definitions ...................................................................................................................... 4

4 Symbols and Units ........................................................................................................................... 5

5 Calculation of the electrical energy efficiency (h ) ................................................................ 6

elecwh

6 Measured parameters ...................................................................................................................... 6

7 General conditions for measurements .......................................................................................... 6

8 Reference conditions ....................................................................................................................... 7

9 Test procedures ............................................................................................................................... 9

10 Data Report ....................................................................................................................................18

Annex A (normative) Calculation of the specific energy efficiency and of the Annual

Consumption of electric energy .........................................................................................................19

Annex ZZA (informative) ........................................................................................................................21

Annex ZZB (informative) ........................................................................................................................22

Bibliography ..........................................................................................................................................23

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SIST EN 50440:2016
EN 50440:2015 (E)
European foreword

This document (EN 50440:2015) has been prepared by CLC/TC 59X "Performance of household and

similar electrical appliances".
The following dates are fixed:
• latest date by which this document has
(dop) 2016-10-05
to be implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national
(dow) 2018-10-05
standards conflicting with this
document have to be withdrawn

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

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

patent rights.

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

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

For the relationship with EU Directives see informative Annexes ZZA and ZZB, which are integral

parts of this document.
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SIST EN 50440:2016
EN 50440:2015 (E)
1 Scope

This European Standard specifies methods for measuring the performance of electric storage water

heaters for the production of sanitary 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 standard 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 storage 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 4.

NOTE 2 This standard does not specify performance or safety requirements. For safety requirements see EN 60335-1 in

conjunction with EN 60335-2-21.
2 Normative references
Not applicable.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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
to heat water for the 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 energised for 24 h per day

3.4
off-peak storage water heater

storage water heater that is designed to supply hot water 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 7:00h

and 22:00h 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 22:00h and 7:00h during the test with the 24h tapping pattern.
3.5
load profile

means the output performance (in terms of flow-rates, temperatures, tapping pattern, etc.) of a storage

water heater when fulfilling its primary function under specific ambient conditions (see Tables 3 and 4),

as declared by the manufacturer
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SIST EN 50440:2016
EN 50440:2015 (E)
3.6
energy efficiency

means the ratio between the delivered energy in the sanitary hot water for its load profile and the

consumed electrical energy
3.7
storage volume
rated quantity of water stored in the appliance
Note 1 to entry: This is declared in litres.
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 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

4 Symbols and Units
Table 1 – Symbols
Unit Description
Symbol
[%] Energy efficiency of a storage water heater.
elecwh

Q [kWh] Reference energy for the 24 h tapping pattern for the load profile of the water

ref
heater.
Q [kWh] Electricity consumption with the relevant 24 h tapping pattern.
elec
[°C]
θ´ mean water temperature for the determination of θ , measured at the outlet
p p

f [l/min] Minimum flow rate which hot water is contributing to the reference energy as

specified in Table 4.

T [°C] The water temperature at which hot water starts contributing to the reference

energy as specified in table 4

T [°C] Minimum water temperature to be achieved during water draw off as specified

in Table 4
Q [kWh] Measured electricity consumption over 24 h test (step 4).
testelec
Q Useful energy content of the hot water of n drawn-offs
[kWh]
H2O
full−drawing
Sum of quantity of hot water totally delivered during the tapping period.
[litres]
water
[litres] Measured volume delivered at the mean water temperature.
40_exp
[litres] Mixed water quantity delivered at 40 C.
C [litres] Actual capacity of Water Heater
act
m [kg] Actual weight of water contained inside the tank of the Water Heater
act
smart Presence or not of smart control (value shall be 0 or 1).
SCF Efficiency gain by smart control function.
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SIST EN 50440:2016
EN 50440:2015 (E)
5 Calculation of the electrical energy efficiency (h )
elecwh

The electrical energy efficiency (h ) of a storage water heater is the ratio between the delivered

elecwh

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 as Formula 1:

ref
h =
(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 heater,

ref
in kWh;

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;
NOTE SCF=0 in case no smart control is detected during testing (9.2).
6 Measured parameters

The parameters below shall be established following the measurement methods described in following

Clauses 7 and 9:
a) electricity consumption [kWh/d];
b) electrical energy efficiency [%];
c) storage volume [litre].
7 General conditions for measurements
Measurements shall be carried out with a supply of:
Table 2 – Electricity
Permissible
Uncertainty of
deviation
Measured quantity Unit Value measurement Notes
(average over
(accuracy)
test period)
Electricity
Power W ± 2 %
energy kWh ± 2 %
voltage, test-period > 48 h V 230/ 400 ± 4 % ± 0,5 %
voltage, test-period < 48 h V 230/ 400 ± 2 % ± 0,5 %
electric current A ± 0,5 %
frequency Hz 50 ± 1 %
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SIST EN 50440:2016
EN 50440:2015 (E)

Table 3 gives additional test conditions and tolerances for test outputs (i.e. thermal energy).

Table 3 – Test conditions and outputs. Set values and tolerances
Permissible
Permissible
deviations Uncertainty
deviation
of of
Measured quantity Unit Value (average Notes
individual measurement
over test
measured (accuracy)
period)
values
Time
Time s ± 0,1 s
Maximum interval between samples
s 3
(during the deliver of hot water)
Maximum interval between samples
s 60
(during the no-deliver of hot water)
Sanitary water
cold water temperature °C/ K 10 °C +/- 1 K +/- 1 K +/- 0,5 K*
cold water pressure MPa 0,3 MPa ± 5 %
a, b
hot water temperature °C/ K pattern +/- 0,5 K*
volume flowrate l / min pattern ± 1 %
volume measurements l ± 0,5 %
± 2 % ± 2 % ± 2 % c
thermal energy kWh pattern
(overall) (or ±10Wh) (or ±10Wh)
Ambient air
Temperature °C/ K 20 °C ± 1 K ± 1 K

a To be measured by "rapid response thermometer", meaning an instrument that registers within 1 s. at least 90% of the final

temperature rise from 15 to 100 °C when the sensor is plunged in still water.

b Thermocouple with a maximum diameter of 0,5mm, centred in stream, directly at outlet

c Apart from the maximum deviation a correction factor Qref/QH2O is applied, whereby Qref is taken from Table 4 and QH2O

is the energy content of the useful water actually delivered during the test. "Useful water" is water with a temperature higher

than a threshold value Tm for tappings in a profile specified in Table 4.

*Together with the publication task it should be mentioned towards the Commission that this tolerance is hard or

really not to be reached in practice.

All other installation requirements are made according to the manufacturer’s instructions.

8 Reference conditions

Table 4 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;
f) T [°C] minimum (peak) temperature to be achieved during tapping;

g) Q [kWh/d] daily (24 h) useful energy content of all water draw-offs, effectively the sum of all

ref
Q .
tap
For all tests a cold water temperature of (10 ± 2) ºC shall be used.

As much as possible, the test method uses a ‘black-box’ approach, i.e. largely technology

independent. This means amongst others that the laboratory uses the original appliance thermostat, in

the position specified by manufacturer, and at the factory settings.
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SIST EN 50440:2016
EN 50440:2015 (E)
Table 4 –Load profile of water heater (reference test tapping patterns)
XXS XS S M L XL XXL 3XL 4XL

Qtap f Tm Tp Qtap f Tm Tp Qtap f Tm Tp Qtap f Tm Tp Qtap f Tm Tp Qtap f Tm Tp Qtap f Tm Tp Qtap f Tm Tp Qtap f Tm Tp

l/mi l/mi
h h

h kWh ºC ºC kWh l/min ºC ºC kWh l/min ºC ºC kWh l/min ºC ºC kWh l/min ºC ºC kWh l/min ºC ºC kWh l/min ºC ºC kWh l/min ºC ºC kWh ºC ºC

n 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
1,820 1,820
07.15 07.15 6 40 07.15 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

0,105 0,105 0,105 0,105 0,105 0,105
09.30 2 25 3 25 09.30 3 25 3 25 3 25 09.30 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

0,105
12.00 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

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
4,420 6,240
20.46 20.46 10 10 40 20.46 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
0,525 1,400 0,105 4,420 6,240 12,04 24,08
21.30 5 45 21.30 6 40 3 25 10 10 40 21.30 16 10 40 48 40 96 40
21.35 0,105 2 25 21.35 21.35
21.45 0, 105 2 25 21.45 21.45
2,100 2,100 2,100 5,845 11,655 19,070 24,530 46,760 93,520
Qref Qref Qref
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SIST EN 50440:2016
EN 50440:2015 (E)
9 Test procedures
9.1 Standard Test Procedure
9.1.1 Introduction

The following subclauses describe the test procedure to establish the electricity consumption Q

elec
during a 24 h test.
9.1.2 Installation
Install product in test environment according to 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 could be placed under the test object at a distance of 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 700 mm to the sides.

Products designated to be built-in shall be mounted according to 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.
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SIST EN 50440:2016
EN 50440:2015 (E)
Position of the thermocouples for
Vertical and Horizontal models ( ).
Thermocouple or
5 cm
probe position for
reference thermostat
h/2
Circular
Position of thermocouple
welding
or reference probe for
reference thermostat
b) For horizontal water heater
For the horizontal devices, the reference temperature is probed on
the higher generator of the tank, at 5 cm of the circular welding on
the cylindrical part and opposed to the heater.
a) For vertical water heater
Figure 1 – Position of the thermocouples for Vertical and Horizontal models
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SIST EN 50440:2016
EN 50440:2015 (E)
Key
1 thermocouple outlet temperature
2 thermocouple cold water temperature
3 measurement flow rate
4 valve bypass
5 safety valve
6 valve tapping
Figure 2 – example of hydraulic connection (unvented products)

Distance between the cold water inlet of the water heater and the position of the thermocouple

measuring cold water shall be lower or equal to 100 mm.
9.1.3 Stabilisation

Keep product at ambient conditions (test room) until all parts of the product have reached ambient

conditions ± 5 K (at least for 24 h).
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SIST EN 50440:2016
EN 50440:2015 (E)
Figure 3 – Test procedure Figure 4 – Test procedure
for “ENERGIZED APPLIANCES” for “OFF-PEAK APPLIANCES”
9.1.4 Storage volume

STEP 0 of Figures 3 and 4: the volume of the tank in a storage electric water heater is measured as

follows.

The empty water heater is to be weighted; the weight of taps on inlet and/or outlet pipes shall be

considered.

Then the storage water heater is filled with cold water 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 weighted.

The difference of the two weights (m ) is to be converted into the volume in litres.

act
act
C = (2)
act
0.9997

This volume is to be reported in litres to the nearest one-tenth litres. The measured value (actual

value) shall not be more than 2 % lower than the rated value.
9.1.5 Filling and heat-up

STEP 1 of Figures 3 and 4: products with storage-facilities shall be filled with cold water (10 ± 2) °C.

Filling stops at the applicable cold water pressure (see Table 4).

STEP 2 of Figures 3 and 4: the product is energized to reach “out-of-the-box” factory settings, e.g. for

storage temperature. The product’s own means of control (thermostat) shall be used. The next stage

starts at thermostat cut out.
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SIST EN 50440:2016
EN 50440:2015 (E)
9.1.6 Stabilisation at zero-load

STEP 3 of Figures 3 and 4: 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.
9.1.7 Tapping

STEP 4 of Figures 3 and 4: for the selected Load Profile, draw-offs are made in accordance with the

specifications of the appropriate 24 h tapping pattern in Table 4. Tapping pattern starts directly after

thermostat cut out from stabilisation part with the first tapping at 7:00h time-value as implied in

Table 4. The tapping period ends 24 h later. The required useful energy content of the hot water is the

total Q [in kWh] in Table 4.
ref

During the tapping stage technical parameters (power, temperature, etc.) are established in

accordance with specifications in Table 4. During draw-offs the recommended maximum sample rate

is 3 s (see Table 3). Recorded values shall be part of the technical test report.

Electricity consumption over the 24 h test Q [kWh electricity] will be measured over 24 h (i.e. t -

testelec 5
t ).

Useful energy content of the hot water drawn-off Q [kWh] is determined as described below:

H2O

• follows from average in-/outlet temperature difference during the useful tapping period in [K],

the tapped useful water volume in litre. and the specific heat of water c
(1,163 x 10 kWh/(litre x K)):
Q [i]=∆T[i]×V[i]×c (3)
H2O w
where:
Q [i] is the "Energy content" of one draw-off in [kWh];
H2O
ΔT[i]
is the average in-/outlet temperature difference during the
useful tapping period in [K];
V[i]
is the tapped useful water volume [litres];
c (1,163x10 kWh/(litre x K)) is the specific heat of water.
For all the n draw-offs of one tapping profile the energy content is the sum:
Q = Q [i] for i=1to n (4)
H2O ∑ H2O

This formula can have many formats, e.g. more dynamic formats using flowrate and instantaneous

temperature differences, but it comes down to the same result.

Products to be classified as “Off-peak” appliances shall be energized for a maximum period of 8

consecutive hours (t -t ) during 22:00h and 7:00h of the 24 h tapping pattern as specified in Table 4.

5 4
full−drawing

In addition V [litres] will be recorded; it is the sum of quantity of hot water totally delivered

water
during the tapping period.
9.1.8 Reporting of Q
elec

Q shall be corrected for any energy surplus or deficit outside the strict 24 h tapping period, i.e. a

testelec

possible energy difference before and after the tapping cycle is taken into account. Furthermore, any

surplus or deficit in the delivered useful energy content of the hot water is taken into account in the

following equations for Q .
elec
---------------------- Page: 15 ----------------------
SIST EN 50440:2016
EN 50440:2015 (E)
  1,163×C ×(T(t )−T(t ))
 
ref
act 3 3 5 5
Q = × Q + [kWh] (5)
elec  testelec 
 
Q 1000
 
 H2O

where T and T are water temperatures measured at the dome of water heater, respectively at t and

3 5 3
t .
9.1.9 Re-stabilisation at zero-load

STEP 5 of Figures 3 and 4: keep product at nominal operating conditions without draw-offs during at

least 12 h. For products with storage-facilities subject to a control cycle this stage ends at the first

thermostat cut-out after 12 h.
9.1.10 Mixed water quantity delivered at 40 °C

STEP 6 of Figures 3 and 4: quantity of water at 40 °C, which has the same heat content (enthalpy) as

the hot water which is delivered above 40 °C at the output of the water heater.

Immediately following measurement according to “Re-stabilization at zero-load” (STEP 5), the water

heater is switched off after the last cut-out of the thermostat.

Then a quantity of water equal to the rated capacity is withdrawn through the outlet at a constant rate

of flow by supplying cold water; the flow of water from open outlet water-heaters is controlled by the

inlet valve. The flow in any other type of water-heaters is kept constant by means of a valve fitted in

the outlet or the inlet.

The rate of flow is adjusted to the maximum value showed on “Water heater load profile” chosen to

perform the appliance during the tapping cycle.

T [°C] is the water temperature, without withdrawal of water, measured with a thermocouple placed

set

inside the upper section of the tank. For metal tanks the thermocouple may be placed on the outer

surface of the tank as well. This value is the water temperature measured after the last cut-out of the

thermostat during the “Re-stabilization at zero-load” step.
θ [°C] is the average temperature of inlet cold water during the test.

θ' [°C] is the average temperature of outlet water and its normalized value is named θ [°C]; it is to be

p p
calculated in according to the following formula:
 
 
θ' −θ
 
p c
 
θ [°C]=(T −10)× +10
(6)
set  
T −θ 
 set c

NOTE Temperature readings are preferable taken continuously. Alternatively, they may be taken at equal intervals evenly

spread over the discharge, for example every 5 litres (maximum). If there is a sharp drop in temperature, additional readings

may be necessary in order to correctly calculate the average value θ’ .

Outlet water temperature shall always be ≥ 40 °C which is to be taken into account for the calculation

of θ .

The volume V [litres] which corresponds to the quantity of water delivered at least 40 °C is to be

40_exp
considered.

Quantity of hot water V [litres] delivered with a temperature of at least 40 °C will be calculated by the

following equation:
(θ −10)
V [litres]=V ⋅ (7)
40 40exp
---------------------- Page: 16 ----------------------
SIST EN 50440:2016
EN 50440:2015 (E)
9.2 Smart Control Test procedure
9.2.1 Measurement procedure

The Smart Control test procedure is based on two periods of test; they are named “reference period”

and “smart period”. During the first period, “reference period”, the smart control does not influence the

heating procedure and the appliance us
...