EN 50440:2015/A2:2026

• Abstract:

  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 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 4. NOTE 2 This standard does not specify performance or safety requirements. For safety requirements see EN 60335-1:2020 in conjunction with EN 60335-2-21:2023

• Status: Published
• Publication Date: 08-Oct-2026
• ICS: 91.140.65 - Water heating equipment
• Technical Committee: CLC/TC 59X - Consumer information related to household electrical appliances
• Drafting Committee: CLC/TC 59X/WG 04 - Water heaters
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 09-Oct-2026
• Due Date: 28-Jan-2027
• Completion Date: 09-Oct-2026
• Ref Project: SIST EN 50440:2016/oprA2:2026 - Efficiency of domestic electrical storage water heaters and testing methods

• Amends: EN 50440:2015 - Efficiency of domestic electrical storage water heaters and testing methods
• Effective Date: 13-Aug-2024

EN 50440:2015/A2:2026 is a CLC amendment to EN 50440:2015 for domestic electric storage water heaters. It updates the methods used to measure performance, verify declared load profiles, and calculate efficiency and annual electricity consumption for household and similar sanitary hot water use. It is aimed at manufacturers, test laboratories, certification bodies, and buyers who need a common basis for comparing declared performance.

What does EN 50440:2015/A2:2026 specify?

EN 50440:2015/A2:2026 modifies the European Standard for measuring the performance of electric storage water heaters. The amendment is read together with EN 50440:2015 and focuses on how the water heater is tested, how the load profile is checked, and what data are reported.

It covers these parts of the document:

Part	What it covers
Clause 1	Scope
Clause 3	Terms and definitions
Clause 4	Symbols and units
Clause 7	General conditions for measurements
Clause 8	General test conditions
Clause 9	Test procedures
Clause 10	Data report
Annex A	Calculation of the specific energy efficiency and annual consumption of electric energy
Bibliography	Reference update

The scope still excludes storage water heaters that use electricity only as a secondary heating source, water heaters without a tank, and heaters outside the smallest or biggest load profile limits. The document also states that it does not set performance or safety requirements, and points safety readers to EN IEC 60335-1 with EN IEC 60335-2-21.

What are the key requirements of EN 50440:2015/A2:2026?

The amendment mainly tightens how declared performance is checked and how the test results are turned into reported values.

• Clause 7 updates measurement conditions and tolerances. It sets the test conditions for time, sanitary water temperature, pressure, ambient air temperature, and measurement uncertainty. In practice, this tells the lab how closely the test rig must control the water and air conditions so results can be compared across products.

• Clause 8 introduces a structured load-profile verification. The declared load profile is checked against the maximum load profile, or the next lower one, using the measured heat-up energy and the operating-point tables. In practice, the manufacturer must declare a profile the product can actually meet under the defined draw-off pattern.

• Clause 8 separates energized storage water heater and off-peak storage water heater checks. For energized storage water heater, the largest load profile is the one where all stated conditions are met. For off-peak storage water heater, the declared load profile is assumed to be M or higher and is verified with two energy-based conditions. This matters because the two product types are judged with different assumptions.

• Clause 8 and Table 6 define the operating points used for verification. The tables link reference energy, maximum draw-off, equivalent 40 °C water, and the temperature criterion after the largest one-hour-and-half sum of draw-offs. In practice, the test laboratory uses these values to decide which load profile is justified.

• Clause 9 adds the rated heat output. Rated heat output is defined from electrical energy efficiency and nominal power input, and the electricity consumption during the heat-up period is measured in STEP 2. This gives a consistent reported output value for comparison.

• Clause 9 adds a default sound power level for units without moving parts. A value of 15 dB is set for electric storage water heaters without moving parts such as a pump. This gives report users a default acoustic value where no moving parts are present.

• Clause 10 expands the data report. The report now includes rated heat output. In practice, this makes the declared technical data more complete for procurement and conformity documentation.

• Annex A updates the efficiency and annual-consumption calculation. The amendment adjusts the notation and the electricity conversion coefficient. This affects the final efficiency figures and annual energy calculations used in documentation.

What terms does EN 50440:2015/A2:2026 define?

• Rated heat output (P) - The heat output of the water heater under standard rating conditions, expressed in kW.
• Electricity consumption during the heat-up period (Qheat-up) - The electricity used during STEP 2 of the test, which is used as the energy basis for several calculations.
• Nominal power input (Pnom) - The power input assigned to the appliance by the manufacturer and used in the rated heat output formula.
• Rated capacity (C) - The manufacturer-assigned capacity of the water heater, used in load-profile verification.
• Declared load profile (LPdec) - The load profile claimed by the manufacturer and checked against the test results.
• Maximum load profile (LPmax) - The largest load profile the product can meet under the stated verification rules.
• Equivalent energy of the minimum quantity of water delivered at 40 °C (Qequiv40) - The energy equivalent used to check whether the heater can deliver the required usable hot water.

Who uses EN 50440:2015/A2:2026?

EN 50440:2015/A2:2026 is used by manufacturers of domestic electric storage water heaters, test laboratories, certification bodies, and technical teams that prepare product declarations. It is also useful for quality managers, specifiers, and buyers who need to compare reported efficiency, load profile, and annual consumption on a common test basis.

What changed in EN 50440:2015/A2:2026 from the previous edition?

This amendment updates EN 50440:2015 by revising the scope note for safety references, adding the term rated heat output, expanding symbols and units, tightening test conditions, and replacing the general test conditions section with load-profile verification rules. It also adds the rated heat output calculation, a default sound power level for units without moving parts, a new data-report item, revised Annex A calculations, and an updated bibliography reference to EN IEC 60335-2-21.

Which standards are used with EN 50440:2015/A2:2026?

• EN IEC 60335-1 - gives the general safety requirements for household and similar electrical appliances.
• EN IEC 60335-2-21 - gives the particular safety requirements for storage water heaters and is the companion safety standard named alongside EN IEC 60335-1.

What does the EN 50440:2015/A2:2026 document contain?

The document contains updated tables for measurement conditions, test tolerances, load-profile schedules, operating points, and data reporting. It also contains formulas for load-profile verification, rated heat output, and the calculation of specific energy efficiency and annual consumption. These methods are used in testing, conformity assessment, and product documentation so that the declared performance can be checked in a repeatable way.

SLOVENSKI STANDARD
01-april-2026
Učinkovitost gospodinjskih električnih akumulacijskih grelnikov vode in
preskusne metode
Efficiency of domestic electrical storage water heaters and testing methods
Effizienz von elektrischen Warmwasserspeichern für den Hausgebrauch und
Prüfverfahren
Efficacité des chauffe-eau électriques à accumulation et méthodes associées
Ta slovenski standard je istoveten z: EN 50440:2015/prA2:2026
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.

EUROPEAN STANDARD DRAFT
EN 50440:2015
NORME EUROPÉENNE
EUROPÄISCHE NORM
prA2
February 2026
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 und Prüfverfahren
This draft amendment prA2, if approved, will modify the European Standard EN 50440:2015; it is submitted to CENELEC members for
enquiry.
Deadline for CENELEC: 2026-05-01.

It has been drawn up by CLC/TC 59X.

If this draft becomes an amendment, CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which
stipulate the conditions for giving this amendment the status of a national standard without any alteration.

This draft amendment was established by CENELEC 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the 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 Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Project: 80529 Ref. No. EN 50440:2015/prA2:2026 E

EN 50440:2015/prA2:2026 (E)
Contents Page
European foreword . 3
1 Modification to Clause 1, Scope . 4
2 Modification to Clause 3, “Terms and definitions” . 4
3 Modification to Clause 4, “Symbols and Units” . 4
4 Modification to Clause 7, “General conditions for measurements” . 4
5 Modification to Clause 8, “Reference conditions” . 5
6 Modification to Clause 9, “Test procedures”.10
7 Modification to Clause 10, Data Report .11
8 Modification to Annex A, “Calculation of the specific energy efficiency and of the Annual
Consumption of electric energy” .11
9 Modification to the Bibliography .11
EN 50440:2015/prA2:2026 (E)
European foreword
This document (EN 50440:2015/prA2:2026) has been prepared by CLC/TC 59X “Performance of household
and similar electrical appliances”, the secretariat is held by DKE.
This document is currently submitted to the Enquiry.
The following dates are proposed:
• latest date by which the existence of this (doa) dav + 6 months
document has to be announced at national level
• latest date by which this document has to be (dop) dav + 12 months
implemented at national level by publication of
an identical national standard or by
endorsement
• latest date by which the national standards (dow) dav + 36 months
conflicting with this document have to be (to be confirmed or
withdrawn modified when voting)
This document is read in conjunction with EN 50440:2015.
EN 50440:2015/prA2:2026 (E)
1 Modification to Clause 1, Scope
Replace the second dash item in the NOTE 1 with the following:
“- storage water heaters that do not use a tank to store hot water;”
Replace NOTE 2 with the following:
NOTE 2 This standard does not specify performance or safety requirements. For safety requirements see
EN IEC 60335-1 in conjunction with EN IEC 60335-2-21.
2 Modification to Clause 3, “Terms and definitions”
NOTE OF THE SECRETARY: It is suggested to keep “energized” in definition 3.3 instead of the suggested
“energised” term as it would imply multiple modification in the standard impairing the readability of an
amendment. It would have been easier in a consolidation version or new edition).
Add the following term entry:
”3.10
rated heat output
P
rated
heat output of the water heater when providing water heating at standard rating conditions, expressed in kW”
3 Modification to Clause 4, “Symbols and Units”
Add the following lines in Table 1:
“
Table 1 — Symbols
Symbol Unit Description
Q kWh Electricity consumption during the heat-up period (step 2)
heat-up
P kW Rated power output in kW
rated
P kW Nominal power input assigned to the appliance by the manufacturer
nom
C l Rated capacity of Water Heater, assigned to the appliance by the manufacturer
rated
“
4 Modification to Clause 7, “General conditions for measurements”
Replace Table 3 with the following:
EN 50440:2015/prA2:2026 (E)
“
Table 3 — Test conditions and outputs. Set values and tolerances
Permissible Permissible
Uncertainty of
deviation deviations of
Measured quantity Unit Value measurement Notes
(average over test individual
(accuracy)
period) measured values
Time
Time s    ±0,1
Maximum interval between
samples (during the deliver s 3
of hot water)
Maximum interval between
samples (during the no- s 60
deliver of hot water)
Sanitary water
°C/
cold water temperature 10 ±1 ±1 ±0,5
K
0,3
cold water pressure MPa   ±5 %

°C/
a, b
hot water temperature pattern   ±0,5
K
l /
volume flowrate pattern   ±1 %
min
volume measurements l    ±0,5 %
±2 % ±2 %
c
thermal energy kWh pattern ±2 % (overall)
(or ± 10 Wh) (or ± 10 Wh)
Ambient air
°C/
Temperature 20 ±1  ±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 0,5 mm, 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 th
...