Installation of thermal energy meters - Guidelines for the selection, installation and operation of thermal energy meters

The EN 1434 standards provides technical principles and practical advice in selecting, installing and commissioning of thermal energy meters. However, because a standard cannot cover all areas completely, this document assists users of thermal energy meters.

Installation von thermischen Energiemessgeräten - Richtlinien für Auswahl, Installation und Betrieb von thermischen Energiemessgeräten

Compteur d’énergie thermique installation - Lignes directrices pour la sélection, l’installation et le fonctionnement des compteurs d’énergie thermique

Vgradnja merilnikov toplote - Smernice za izbiro, vgradnjo in delovanje merilnikov toplote

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Published
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
27-Jan-2021
Completion Date
27-Jan-2021

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SLOVENSKI STANDARD
SIST-TP CEN/TR 13582:2021
01-april-2021
Nadomešča:
SIST CR 13582:2001

Vgradnja merilnikov toplote - Smernice za izbiro, vgradnjo in delovanje merilnikov

toplote

Installation of thermal energy meters - Guidelines for the selection, installation and

operation of thermal energy meters

Installation von thermischen Energiemessgeräten - Richtlinien für Auswahl, Installation

und Betrieb von thermischen Energiemessgeräten

Compteur d’énergie thermique installation - Lignes directrices pour la sélection,

l’installation et le fonctionnement des compteurs d’énergie thermique
Ta slovenski standard je istoveten z: CEN/TR 13582:2021
ICS:
17.200.10 Toplota. Kalorimetrija Heat. Calorimetry
SIST-TP CEN/TR 13582:2021 en

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

---------------------- Page: 1 ----------------------
SIST-TP CEN/TR 13582:2021
---------------------- Page: 2 ----------------------
SIST-TP CEN/TR 13582:2021
CEN/TR 13582
TECHNICAL REPORT
RAPPORT TECHNIQUE
January 2021
TECHNISCHER BERICHT
ICS 17.200.10
English Version
Installation of thermal energy meters - Guidelines for the
selection, installation and operation of thermal energy
meters

Compteur d'énergie thermique installation - Lignes Installation von thermischen Energiemessgeräten -

directrices pour la sélection, l'installation et le Richtlinien für Auswahl, Installation und Betrieb von

fonctionnement des compteurs d'énergie thermique thermischen Energiemessgeräten

This Technical Report was approved by CEN on 4 January 2021. It has been drawn up by the Technical Committee CEN/TC 176.

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, Turkey 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

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 13582:2021 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST-TP CEN/TR 13582:2021
CEN/TR 13582:2021 (E)
Contents Page

European foreword ...................................................................................................................................................... 4

Introduction .................................................................................................................................................................... 5

1 Scope .................................................................................................................................................................... 6

2 Normative references .................................................................................................................................... 6

3 Terms and definitions ................................................................................................................................... 6

4 Selecting a metering device for thermal energy .................................................................................. 7

4.1 General................................................................................................................................................................ 7

4.2 Metrological characteristics ....................................................................................................................... 8

4.3 Environmental classifications .................................................................................................................... 8

5 Dimensioning ................................................................................................................................................... 9

5.1 General................................................................................................................................................................ 9

5.2 Determining the thermal energy power ................................................................................................. 9

5.3 Thermal energy load ..................................................................................................................................... 9

5.4 Thermal energy power for water heating ............................................................................................ 10

5.5 Thermal energy power for ventilation and air conditioning systems ....................................... 11

5.6 Thermal energy power for cooling systems ........................................................................................ 11

5.7 Thermal energy power for engineering purposes ............................................................................ 11

6 Determining the flow rate ......................................................................................................................... 12

6.1 Principles of thermodynamics ................................................................................................................. 12

7 Selecting a flow sensor for a thermal energy meter ......................................................................... 13

8 Checking the flow sensor design after commissioning ................................................................... 14

8.1 General.............................................................................................................................................................. 14

8.2 Operating conditions ................................................................................................................................... 14

8.3 Flow sensors ................................................................................................................................................... 15

8.4 Temperature sensors .................................................................................................................................. 20

8.5 Calculators ....................................................................................................................................................... 23

9 Arranging of meters for thermal energy .............................................................................................. 24

9.1 General.............................................................................................................................................................. 24

9.2 Environment ................................................................................................................................................... 24

9.3 Flow sensors ................................................................................................................................................... 25

9.4 Temperature sensors .................................................................................................................................. 28

9.5 Calculators ....................................................................................................................................................... 32

10 Installing thermal energy meters ........................................................................................................... 33

10.1 General.............................................................................................................................................................. 33

10.2 Mechanics ........................................................................................................................................................ 33

10.3 Connecting to pipes ...................................................................................................................................... 33

10.4 Electrical connections ................................................................................................................................. 33

10.5 Commissioning .............................................................................................................................................. 34

11 Monitoring operation .................................................................................................................................. 34

11.1 General.............................................................................................................................................................. 34

11.2 Measuring cooling supply using water or anti-freeze mixtures as medium ........................... 34

11.3 Requirements for the system arrangement of cooling measurements ..................................... 39

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SIST-TP CEN/TR 13582:2021
CEN/TR 13582:2021 (E)

12 Other liquids than water ............................................................................................................................ 42

12.1 Introduction ................................................................................................................................................... 42

12.2 Physical impact .............................................................................................................................................. 42

12.3 Flow measurement ...................................................................................................................................... 44

12.4 Temperature difference measurement ................................................................................................ 49

12.5 Calculator ........................................................................................................................................................ 49

Bibliography ................................................................................................................................................................. 50

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SIST-TP CEN/TR 13582:2021
CEN/TR 13582:2021 (E)
European foreword

This document (CEN/TR 13582:2021) has been prepared by Technical Committee CEN/TC 176 “Thermal

energy meters”, the secretariat of which is held by SIS.

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.

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SIST-TP CEN/TR 13582:2021
CEN/TR 13582:2021 (E)
Introduction

Metering devices for thermal energy (heat and cooling meters) are only working correctly and

consistently if the system design considers the minimum and maximum ratings for temperature,

temperature difference and flow rate according to the approved ranges. The metering device should be

selected for the approved legal range and the application area. The thermal energy meter should be

installed according to the valid requirements. During commissioning the thermal energy meter is checked

for both correct installation and full functionality and afterwards sealed against unauthorized opening.

According to the European harmonized standard EN 1434-6 a commissioning is obligatory to ensure that

the metering device accurately measures the planned or predicted consumption.

Installing the metering devices or their sub-assemblies incorrectly (e.g. an incorrect combination of

temperature sensors with non-approved pockets) does not guarantee the measuring accuracy. Hence,

the measurement deviations may exceed the permissible error limits. National calibration laws state that

the metering point operator should ensure that the metering device is set up, connected, handled and

maintained correctly to guarantee the measuring accuracy. Incorrect measurements result in bills that

cannot be used in business transactions.

The metering point operator is in district heating networks responsible for a proper installation and

commissioning of the metering devices. The metering point operator can also delegate this task to a

service company. The building owner or the building owner’s representative (e.g. a metering service

company) is in sub metering applications responsible for a proper installation and commissioning of the

metering devices.

The EN 1434 standards provide technical principles and practical advice in selecting, installing and

commissioning of thermal energy meters. However, because a standard cannot cover all areas

completely, this report shall assist users of thermal energy meters.
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SIST-TP CEN/TR 13582:2021
CEN/TR 13582:2021 (E)
1 Scope

The EN 1434 standards provide technical principles and practical advice in selecting, installing and

commissioning of thermal energy meters. However, because a standard cannot cover all areas

completely, this document assists users of thermal energy meters.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

EN 1434-1, Thermal energy meters - Part 1: General requirements
EN 1434-2, Thermal energy meters - Part 2: Constructional requirements
3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 1434-1 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
DH (network)
district heating system, DC: district cooling system
3.2
meter: thermal energy meter
heat meter or cooling meter
3.3
water
domestic water
3.4
hot water
domestic hot water
3.5
fluid additive
fluid used to supplement a shortage of the heat transfer medium due to leaks
3.6
fluid
heat transfer medium in a DH/DC system
3.7
MID
Measurement Instrument Directive 2014/32/EU
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SIST-TP CEN/TR 13582:2021
CEN/TR 13582:2021 (E)
4 Selecting a metering device for thermal energy
4.1 General

A thermal energy meter consists of the following three parts: a flow sensor, a temperature sensor pair

and a calculator (see Figure 1).

These sub-assemblies can be defined as complete instruments, combined instruments or hybrid

instruments (see EN 1434-1).

The calculator unit calculates the energy consumption using the signals from the temperature sensor pair

and the flow sensor.

The minimum temperature difference of the calculator shall not fall below the smallest permissible value

(according to MID the minimum temperature difference is 3 K).

The temperature sensors are usually platinum resistance thermometers of type Pt 100, Pt 500 or Pt 1000.

The sensor pair determines the temperature difference between the inlet (flow) and outlet (return) of

the thermal conveying medium.

The flow sensor is granted an error limit of 2 % to 5 %. Due to faulty design, incorrect installation or wear

the wider error limits of this part/sub-assembly of a meter is exceeded occasionally. This case can be

avoided by selecting the correct flow sensor. An overview of the different types of flow sensors is given

in 8.3.7.
Key
1 inlet
2 outlet
3 calculator
4 outlet temperature sensor
5 inlet temperature sensor
6 flow sensor
7 thermal load
Figure 1 — Thermal energy meter

When operating the heat exchanger circuit system, one may discover that the chosen thermal energy

meter design is not applicable due to the actual requirements.
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SIST-TP CEN/TR 13582:2021
CEN/TR 13582:2021 (E)

Flow sensors that are designed for higher flow rates may not have the required accuracy at low flow rates.

If the actual flow rate is below the minimum permissible flow rate, measurements may be skipped until

the measurement fails completely.

Fast changes in energy consumption that place high demands on the dynamics of the meter may cause

significant deviations in the measurement accuracy of the accumulated energy. Fast-response meters

provide measurement characteristics that reduce this deviation (see 8.5.4)

The effects of dirt deposits and flow disturbances over the entire service life of the flow sensors shall be

considered when selecting a meter.
4.2 Metrological characteristics

The accuracy classes and the maximum permissible relative errors of thermal energy meters are

described in EN 1434-1. Be aware that some national regulations do not allow the use of class 3 meters

at all and that other national regulations do not allow the use of class 3 meters for e.g. for q 6 m /h and

higher.
Class 2 accuracy is the most frequently used accuracy class for flow sensors.

Due to the very high requirements on both flow sensors and test equipment, the availability of class 1

flow sensors is very limited.
4.3 Environmental classifications

The environmental classes are described in EN 1434-1. Thermal energy meters have an environmental

classification A, B and C regarding Domestic/Industrial EMC requirements and Indoor/Outdoor ambient

conditions.
Table 1 — Relationship between EN 1434-1 and MID re. EMC levels
EN 1434-1 MID (2014/32/EU)
Domestic EMC level Class A and B E1
Industrial EMC level Class C E2

Meters with Class C (E2) marking can be used also in domestic installations, but meters with Class A and

B (E1) shall not be used in industrial installations (see Table 1).

Classes A and C are defined for indoor installations with +5 °C to 55 °C ambient temperature.

Class B is defined for outdoor installation. Since the availability of thermal energy meters for outdoor

installation is limited, special care shall be taken to select a suitable meter or to select a suitable protective

cabinet.

Most thermal energy meters are installed in locations without any vibration. For such installations,

meters with the mechanical class M1 are suitable. In case some vibrations may occur at the installation

site a meter with class M2 shall be selected. In case of more intense vibrations a meter with class M3 shall

be selected (see Table 4 for more details).
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SIST-TP CEN/TR 13582:2021
CEN/TR 13582:2021 (E)
5 Dimensioning
5.1 General

When selecting a thermal energy meter, it is important to determine the upper and lower flow limits for

the flow sensor as required by the operating conditions. Based on the range for nominal flow q and

minimum flow q one needs to select a suitable flow sensor from the various devices offered by different

manufacturers. This selection results in the nominal diameter of the measuring line where the flow

sensor shall be installed.

Simply selecting a flow sensor according to the nominal diameter of an existing pipe is not necessarily

correct. Otherwise the coverage of the lower flow range may be insufficient.

It is often good practice that flow sensor sizes of one nominal diameter smaller than the pipe are chosen

when the expected average flow rates are low.

The thermal energy output commissioned with the customer and the maximum inlet and outlet

temperature for the planned application build the base for calculating the thermal energy supply.

In transfer stations for district heating and cooling, the fluid flow rate shall be limited to the

commissioned value by using a flow rate limiter and/or a differential pressure controller. The controller

protects the consumer circuit and the flow sensor from overloading. Arrange the controller in series after

the flow sensor in the outlet to avoid additional disturbances in the flow profile before the flow sensor.

The expected yearly average flow rate, when known, should preferably be around 2/3 of the nominal

flow q of the flow sensor. As for each flow sensor size the nominal flow q corresponds with about 2 m/s

p p

average flow velocity. This is the basis for the relationship between DN and q , and it minimizes the risk

of cavitation as well as loss of accuracy due to wrong meter size.
5.2 Determining the thermal energy power

The metering point operator should perform calculations to determine the thermal energy power only as

a check. Contracted values shall be specified by the customer exclusively.
5.3 Thermal energy load
5.3.1 Standard thermal energy load in new builds

The standard heat load in new buildings and major redevelopments should be determined by a qualified

project engineer, e.g. according to EN 12831-1:2017, Clause 6.
5.3.2 Thermal energy load of buildings with no standard load calculation

If existing buildings are being connected to a thermal energy supply with no standard load calculation,

one could use an approximation or estimation method to determine the thermal energy load for

dimensioning the flow sensor.

If a building connected to a district heating or cooling supply already contains a central heating system,

an approximate thermal energy load can be calculated from an average of the last three years’ annual

consumption, an outside-temperature (see Figure 2) and the expected full usage hours.

Maximum values stored in the thermal energy meter can also be used to determine the output.

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SIST-TP CEN/TR 13582:2021
CEN/TR 13582:2021 (E)

Distribution of outdoor temperatures for five European locations, 1881–2000. An indoor temperature has

been added as example.
Key
X hours per year
Y temperature, °C
1 Palermo, Italy
2 Florence, Italy
3 Strasbourg, France
4 Helsinki, Finland
5 Kiruna, Sweden
6 effective indoor temperature 17 °C
Figure 2 — Outdoor temperature duration in Europe
5.4 Thermal energy power for water heating

The thermal energy power for water heating usually needs to be determined by a qualified project

engineer according to accepted engineering standards (e.g. EN 12831-1).

Using a priority control for the water heating and taking advantage of the building’s heat storage capacity

it may be possible to provide the required thermal energy output for short-term peaks of water heating

without having a significant drop in room temperature.

If a priority control is used the qualified project engineer can select the higher value of the required

thermal energy power between the thermal energy output for central heating or cooling and the thermal

energy power for water heating. The higher value is the deciding factor in the selection of the flow sensor.

Parallel operations shall be considered separately.

1) Source reference: Svend Frederiksen, Svend Werner. 2013. District Heating and Cooling. Studenterlitteratur

AB, Lund. Source reference: Figure 4.2 from “District Heating and Cooling” Svend Frederiksen, Svend Werner

ISBN 978-91-44-08530-2.
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SIST-TP CEN/TR 13582:2021
CEN/TR 13582:2021 (E)
See Figure 3 for outdoor temperature duration in Europe.
Key
X number of normal apartments
Y required power (kW)
Figure 3 — Outdoor temperature duration in Europe
5.5 Thermal energy power for ventilation and air conditioning systems

The thermal energy power required for ventilation and air conditioning systems should be calculated by

a qualified project engineer.

Depending on climatic requirements, the flow sensor may encounter flow rate peaks during the low load

season if there are ambient inlet temperatures in the district thermal energy network. These peaks shall

be investigated and considered for dimensioning the flow sensor.
5.6 Thermal energy power for cooling systems

In bifunctional systems the flow sensor shall be selected by the maximum flow required for either heat

or cooling. The power should be calculated by a qualified project engineer.
5.7 Thermal energy power for engineering purposes

When supplying heating or cooling for industrial and commercial engineering, it is recommended that

the requirements of the customer and the customer’s qualified project engineer regarding the flow sensor

design are checked. A modulating operating curve in the district thermal energy network can cause

increased flow rate values, especially when there are power peaks in the low load season. This shall be

considered when dimensioning the flow sensor.

2) Source reference: Svend Frederiksen, Svend Werner. 2013. District Heating and Cooling. Studenterlitteratur

AB, Lund. Source reference: Figure 4.2 from “District Heating and Cooling” Svend Frederiksen, Svend Werner

ISBN 978-91-44-08530-2
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SIST-TP CEN/TR 13582:2021
CEN/TR 13582:2021 (E)
6 Determining the flow rate
6.1 Principles of thermodynamics
6.1.1 General

The nominal heat or cooling load specifies the thermal energy power required at the measuring point in

the (projected) application.

The maximum thermal energy released or absorbed by a thermal conveying medium in a heating or

cooling circuit is calculated as follows:
Q= kV⋅⋅θθ− (1)
( )
where
is the thermal energy power, e.g. kW;
is the flow rate of the thermal conveying medium, in m /h;
k is the thermal coefficient, in kWh/m K;
θ is the design temperature in inlet, in °C;
θ is the design temperature in outlet, in °C.
Convert the formula to calculate the flow rate for the design case.
V= (2)
k⋅θθ−
( )
6.1.2 Total maximum power for heating or cooling

Add the outputs specified in Clause 5 to calculate the total thermal energy power.

QQ=
(3)
tot
i=1
where
 is the total thermal energy power, in kW;
tot
 is the standard thermal load, in kW;
 is the thermal power for hot water heating, in kW;
 
Q Q
NOTE If using priority control, use only the larger value, either or .
1 2

 is the thermal energy power for ventilation and air conditioning systems, in kW;

 is the thermal energy power for engineering purposes, in kW.
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SIST-TP CEN/TR 13582:2021
CEN/TR 13582:2021 (E)
For cooling systems, the thermal load has to be added the same way (identical).
6.1.3 Inlet and outlet temperature

The difference between inlet and outlet temperatures is the temperature difference.

 
∆=Θθ −θ K (4)
inlet outlet 

In general, the inlet temperature of the heating or cooling medium is regulated by the outside

temperature and the outlet temperature is based on the design and operating mode of the heating system.

6.1.4 Thermal coefficient

The thermal coefficient k shall be determined according to EN 1434-1. For example, with θ = 100 °C,

inlet

θ = 50 °C the approximate value of 1,15 [kWh/(m K)] can be expected for outlet meters and

outlet
1,12 [kWh/(m K)] for inlet meters.
7 Selecting a flow sensor for a thermal energy meter

Because the design case described above occurs only for a few days of the year, a flow sensor shall be

selected so that it ensures that the smallest possible deviation occurs over the whole range of the year.

The range of the most frequent flow values (main operation range) at the measuring point is the deciding

factor for selecting the flow sensor.

The operating range of the flow sensor shall be within the approved range which is spread between the

smallest flow q and the nominal flow q .
i p
A flow sensor shall be selected to fulfil all the following criteria:

— the nominal flow q of the flow sensor is as close as possible to the calculated flow rate;

— the minimum flow q of the flow sensor is smaller than/equal to the minimum flow of the thermal

energy circuit;

— the maximum flow q of the flow sensor is reserved for short term overload (1 hour per day; 200

hours per year) in the thermal energy circuit.

If the minimum flow rate of the thermal energy circuit is not covered by the minimum flow q of the flow

sensor, it shall be checked whether a smaller flow sensor will cover the design case better.

To achieve the minimum flow rate of the thermal energy circuit, a flow sensor with a higher dynamic

range, q /q , shall be selected.
p i
The nominal flow q shall not be exceeded when selecting the flow sensor.

Selecting a flow sensor may be easier if technical measures are taken to reduce the fluctuation range of

the flow.

When selecting a flow sensor statutory regulations and standards, such as EN 1434, the operating

conditions, the manufacturer’s installation instructions and nationally applicable requirements shall all

be considered.

The nominal pressure level (PN/PS) of the flow sensor shall correspond to the pressure class at the

measuring point. In praxis the average pressure should be well below PN.

The permissible temperature range of the flow sensor shall comply with the temperature range of the

thermal conveying medium as well as the ambient temperature at the measuring point. Because of

temperature stress, the flow sensor should generally be installed in the outlet. This is the cooler pipe for

flow sensors in heat meters and this is the warmer pipe for cooling meters.
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SIST-TP
...

SLOVENSKI STANDARD
kSIST-TP FprCEN/TR 13582:2020
01-november-2020

Vgradnja merilnikov toplote - Smernice za izbiro, vgradnjo in delovanje merilnikov

toplote

Installation of thermal energy meters - Guidelines for the selection, installation and

operation of thermal energy meters

Installation von thermischen Energiemessgeräten - Richtlinien für Auswahl, Installation

und Betrieb von thermischen Energiemessgeräten

Compteur d’énergie thermique installation - Lignes directrices pour la sélection,

l’installation et le fonctionnement des compteurs d’énergie thermique
Ta slovenski standard je istoveten z: FprCEN/TR 13582
ICS:
17.200.10 Toplota. Kalorimetrija Heat. Calorimetry
kSIST-TP FprCEN/TR 13582:2020 en

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

---------------------- Page: 1 ----------------------
kSIST-TP FprCEN/TR 13582:2020
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kSIST-TP FprCEN/TR 13582:2020
FINAL DRAFT
TECHNICAL REPORT
FprCEN/TR 13582
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
September 2020
ICS 17.200.10
English Version
Installation of thermal energy meters - Guidelines for the
selection, installation and operation of thermal energy
meters

Compteur d'énergie thermique installation - Lignes Installation von thermischen Energiemessgeräten -

directrices pour la sélection, l'installation et le Richtlinien für Auswahl, Installation und Betrieb von

fonctionnement des compteurs d'énergie thermique thermischen Energiemessgeräten

This draft Technical Report is submitted to CEN members for Vote. It has been drawn up by the Technical Committee CEN/TC

176.

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, Turkey and

United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are

aware and to provide supporting documentation.

Warning : This document is not a Technical Report. It is distributed for review and comments. It is subject to change without

notice and shall not be referred to as a Technical Report.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TR 13582:2020 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
kSIST-TP FprCEN/TR 13582:2020
FprCEN/TR 13582:2020 (E)
Contents Page

European foreword ...................................................................................................................................................... 4

Introduction .................................................................................................................................................................... 5

1 Scope .................................................................................................................................................................... 6

2 Normative references .................................................................................................................................... 6

3 Terms and definitions ................................................................................................................................... 6

4 Selecting a metering device for thermal energy .................................................................................. 7

4.1 General................................................................................................................................................................ 7

4.2 Metrological characteristics ....................................................................................................................... 8

4.3 Environmental classifications .................................................................................................................... 8

5 Dimensioning ................................................................................................................................................... 9

5.1 General................................................................................................................................................................ 9

5.2 Determining the thermal energy power ................................................................................................. 9

5.3 Thermal energy load ..................................................................................................................................... 9

5.4 Thermal energy power for water heating ............................................................................................ 10

5.5 Thermal energy power for ventilation and air conditioning systems ....................................... 11

5.6 Thermal energy power for cooling systems ........................................................................................ 11

5.7 Thermal energy power for engineering purposes ............................................................................ 11

6 Determining the flow rate ......................................................................................................................... 12

6.1 Principles of thermodynamics ................................................................................................................. 12

7 Selecting a flow sensor for a thermal energy meter ......................................................................... 13

8 Checking the flow sensor design after commissioning ................................................................... 14

8.1 General.............................................................................................................................................................. 14

8.2 Operating conditions ................................................................................................................................... 14

8.3 Flow sensors ................................................................................................................................................... 14

8.4 Temperature sensors .................................................................................................................................. 20

8.5 Calculators ....................................................................................................................................................... 23

9 Arranging of meters for thermal energy .............................................................................................. 24

9.1 General.............................................................................................................................................................. 24

9.2 Environment ................................................................................................................................................... 24

9.3 Flow sensors ................................................................................................................................................... 26

9.4 Temperature sensors .................................................................................................................................. 28

9.5 Calculators ....................................................................................................................................................... 32

10 Installing thermal energy meters ........................................................................................................... 33

10.1 General.............................................................................................................................................................. 33

10.2 Mechanics ........................................................................................................................................................ 33

10.3 Connecting to pipes ...................................................................................................................................... 33

10.4 Electrical connections ................................................................................................................................. 33

10.5 Commissioning .............................................................................................................................................. 34

11 Monitoring operation .................................................................................................................................. 34

11.1 General.............................................................................................................................................................. 34

11.2 Measuring cooling supply using water or anti-freeze mixtures as medium ........................... 34

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kSIST-TP FprCEN/TR 13582:2020
FprCEN/TR 13582:2020 (E)

11.3 Requirements for the system arrangement of cooling measurements .................................... 39

12 Other liquids than water ............................................................................................................................ 41

12.1 Introduction ................................................................................................................................................... 41

12.2 Physical impact .............................................................................................................................................. 42

12.3 Flow measurement ...................................................................................................................................... 44

12.4 Temperature difference measurement ................................................................................................ 49

12.5 Calculator ........................................................................................................................................................ 49

Bibliography ................................................................................................................................................................. 50

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European foreword

This document (FprCEN/TR 13582:2020) has been prepared by Technical Committee CEN/TC 176

“Thermal energy meters”, the secretariat of which is held by SIS.
This document is currently submitted to the Vote on TR.
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Introduction

Metering devices for thermal energy (heat and cooling meters) are only working correctly and

consistently if the system design considers the minimum and maximum ratings for temperature,

temperature difference and flow rate according to the approved ranges. The metering device should be

selected for the approved legal range and the application area. The thermal energy meter should be

installed according to the valid requirements. During commissioning the thermal energy meter is checked

for both correct installation and full functionality and afterwards sealed against unauthorized opening.

According to the European harmonized standard EN 1434-6 a commissioning is obligatory to ensure that

the metering device accurately measures the planned or predicted consumption.

Installing the metering devices or their sub-assemblies incorrectly (e.g. an incorrect combination of

temperature sensors with non-approved pockets) does not guarantee the measuring accuracy. Hence,

the measurement deviations may exceed the permissible error limits. National calibration laws state that

the metering point operator should ensure that the metering device is set up, connected, handled and

maintained correctly to guarantee the measuring accuracy. Incorrect measurements result in bills that

cannot be used in business transactions.

The metering point operator is in district heating networks responsible for a proper installation and

commissioning of the metering devices. The metering point operator can also delegate this task to a

service company. The building owner or the building owner’s representative (e.g. a metering service

company) is in sub metering applications responsible for a proper installation and commissioning of the

metering devices.

The EN 1434 standards provide technical principles and practical advice in selecting, installing and

commissioning of thermal energy meters. However, because a standard cannot cover all areas

completely, this report shall assist users of thermal energy meters.
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1 Scope

The EN 1434 standards provide technical principles and practical advice in selecting, installing and

commissioning of thermal energy meters. However, because a standard cannot cover all areas

completely, this document assists users of thermal energy meters.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

prEN 1434-1:2020, Thermal energy meters - Part 1: General requirements
EN 1434-2, Thermal energy meters - Part 2: Constructional requirements
3 Terms and definitions

For the purposes of this document, the terms and definitions given in prEN 1434-1 and the following

apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
DH (network)
district heating system, DC: district cooling system
3.2
meter: thermal energy meter
heat meter or cooling meter
3.3
water
domestic water
3.4
hot water
domestic hot water
3.5
fluid additive
fluid used to supplement a shortage of the heat transfer medium due to leaks
3.6
fluid
heat transfer medium in a DH/DC system
3.7
MID
Measurement Instrument Directive 2014/32/EU
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4 Selecting a metering device for thermal energy
4.1 General

A thermal energy meter consists of the following three parts: a flow sensor, a temperature sensor pair

and a calculator (see Figure 1).

These sub-assemblies can be defined as complete instruments, combined instruments or hybrid

instruments (see prEN 1434-1).

The calculator unit calculates the energy consumption using the signals from the temperature sensor pair

and the flow sensor.

The minimum temperature difference of the calculator shall not fall below the smallest permissible value

(according to MID the minimum temperature difference is 3 K).

The temperature sensors are usually platinum resistance thermometers of type Pt 100, Pt 500 or Pt 1000.

The sensor pair determines the temperature difference between the inlet (flow) and outlet (return) of

the thermal conveying medium.

The flow sensor is granted an error limit of 2 % to 5 %. Due to faulty design, incorrect installation or wear

the wider error limits of this part/sub-assembly of a meter is exceeded occasionally. This case can be

avoided by selecting the correct flow sensor. An overview of the different types of flow sensors is given

in 8.3.7.
Key
1 inlet
2 outlet
3 calculator
4 flow sensor
5 inlet temperature sensor
6 outlet temperature sensor
7 thermal load
Figure 1 — Thermal energy meter

When operating the heat exchanger circuit system, one may discover that the chosen thermal energy

meter design is not applicable due to the actual requirements.
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Flow sensors that are designed for higher flow rates may not have the required accuracy at low flow rates.

If the actual flow rate is below the minimum permissible flow rate, measurements may be skipped until

the measurement fails completely.

Fast changes in energy consumption that place high demands on the dynamics of the meter may cause

significant deviations in the measurement accuracy of the accumulated energy. Fast-response meters

provide measurement characteristics that reduce this deviation (see 8.5.4)

The effects of dirt deposits and flow disturbances over the entire service life of the flow sensors shall be

considered when selecting a meter.
4.2 Metrological characteristics

The accuracy classes and the maximum permissible relative errors of thermal energy meters are

described in prEN 1434-1. Be aware that some national regulations do not allow the use of class 3 meters

at all and that other national regulations do not allow the use of class 3 meters for e.g. for q 6 m /h and

higher.
Class 2 accuracy is the most frequently used accuracy class for flow sensors.

Due to the very high requirements on both flow sensors and test equipment, the availability of class 1

flow sensors is very limited.
4.3 Environmental classifications

The environmental classes are described in prEN 1434-1. Thermal energy meters have an environmental

classification A, B and C regarding Domestic/Industrial EMC requirements and Indoor/Outdoor ambient

conditions.
Table 1 — Relationship between prEN 1434-1 and MID re. EMC levels
prEN 1434-1 MID (2014/32/EU)
Domestic EMC level Class A and B E1
Industrial EMC level Class C E2

Meters with Class C (E2) marking can be used also in domestic installations, but meters with Class A and

B (E1) shall not be used in industrial installations (see Table 1).

Classes A and C are defined for indoor installations with +5 °C to 55 °C ambient temperature.

Class B is defined for outdoor installation. Since the availability of thermal energy meters for outdoor

installation is limited, special care shall be taken to select a suitable meter or to select a suitable protective

cabinet.

Most thermal energy meters are installed in locations without any vibration. For such installations,

meters with the mechanical class M1 are suitable. In case some vibrations may occur at the installation

site a meter with class M2 shall be selected. In case of more intense vibrations a meter with class M3 shall

be selected (see Table 6 for more details).
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5 Dimensioning
5.1 General

When selecting a thermal energy meter, it is important to determine the upper and lower flow limits for

the flow sensor as required by the operating conditions. Based on the range for nominal flow q and

minimum flow q one needs to select a suitable flow sensor from the various devices offered by different

manufacturers. This selection results in the nominal diameter of the measuring line where the flow

sensor shall be installed.

Simply selecting a flow sensor according to the nominal diameter of an existing pipe is not necessarily

correct. Otherwise the coverage of the lower flow range may be insufficient.

It is often good practice that flow sensor sizes of one nominal diameter smaller than the pipe are chosen

when the expected average flow rates are low.

The thermal energy output commissioned with the customer and the maximum inlet and outlet

temperature for the planned application build the base for calculating the thermal energy supply.

In transfer stations for district heating and cooling, the fluid flow rate shall be limited to the

commissioned value by using a flow rate limiter and/or a differential pressure controller. The controller

protects the consumer circuit and the flow sensor from overloading. Arrange the controller in series after

the flow sensor in the outlet to avoid additional disturbances in the flow profile before the flow sensor.

The expected yearly average flow rate, when known, should preferably be around 2/3 of the nominal

flow q of the flow sensor. As for each flow sensor size the nominal flow q corresponds with about 2 m/s

p p

average flow velocity. This is the basis for the relationship between DN and q , and it minimizes the risk

of cavitation as well as loss of accuracy due to wrong meter size.
5.2 Determining the thermal energy power

The metering point operator should perform calculations to determine the thermal energy power only as

a check. Contracted values shall be specified by the customer exclusively.
5.3 Thermal energy load
5.3.1 Standard thermal energy load in new builds

The standard heat load in new buildings and major redevelopments should be determined by a qualified

project engineer, e.g. according to EN 12831-1:2017, Clause 6.
5.3.2 Thermal energy load of buildings with no standard load calculation

If existing buildings are being connected to a thermal energy supply with no standard load calculation,

one could use an approximation or estimation method to determine the thermal energy load for

dimensioning the flow sensor.

If a building connected to a district heating or cooling supply already contains a central heating system,

an approximate thermal energy load can be calculated from an average of the last three years’ annual

consumption, an outside-temperature (see Figure 2) and the expected full usage hours.

Maximum values stored in the thermal energy meter can also be used to determine the output.

Distribution of outdoor temperatures for five European locations, 1881–2000. An indoor temperature has

been added as example
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Key
X hours per year
Y temperature, °C
1 Palermo, Italy
2 Florence, Italy
3 Strasbourg, France
4 Helsinki, Finland
5 Kiruna, Sweden
6 effective indoor temperature 17 °C
1)
Figure 2 — Outdoor temperature duration in Europe
5.4 Thermal energy power for water heating

The thermal energy power for water heating usually needs to be determined by a qualified project

engineer according to accepted engineering standards (e.g. EN 12831).

Using a priority control for the water heating and taking advantage of the building’s heat storage capacity

it may be possible to provide the required thermal energy output for short-term peaks of water heating

without having a significant drop in room temperature.

If a priority control is used the qualified project engineer can select the higher value of the required

thermal energy power between the thermal energy output for central heating or cooling and the thermal

energy power for water heating. The higher value is the deciding factor in the selection of the flow sensor.

Parallel operations shall be considered separately.

1) Source reference: Svend Frederiksen, Svend Werner. 2013. District Heating and Cooling. Studenterlitteratur

AB, Lund. Source reference: Figure 4.2 from “District Heating and Cooling” Svend Frederiksen, Svend Werner

ISBN 978-91-44-08530-2
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Key
X number of normal apartments
Y required power (kW)
Figure 3 — Outdoor temperature duration in Europe
5.5 Thermal energy power for ventilation and air conditioning systems

The thermal energy power required for ventilation and air conditioning systems should be calculated by

a qualified project engineer.

Depending on climatic requirements, the flow sensor may encounter flow rate peaks during the low load

season if there are ambient inlet temperatures in the district thermal energy network. These peaks shall

be investigated and considered for dimensioning the flow sensor.
5.6 Thermal energy power for cooling systems

In bifunctional systems the flow sensor shall be selected by the maximum flow required for either heat

or cooling. The power should be calculated by a qualified project engineer.
5.7 Thermal energy power for engineering purposes

When supplying heating or cooling for industrial and commercial engineering, it is recommended that

the requirements of the customer and the customer’s qualified project engineer regarding the flow sensor

design are checked. A modulating operating curve in the district thermal energy network can cause

increased flow rate values, especially when there are power peaks in the low load season. This shall be

considered when dimensioning the flow sensor.

2) Source reference: Svend Frederiksen, Svend Werner. 2013. District Heating and Cooling. Studenterlitteratur

AB, Lund. Source reference: Figure 4.2 from “District Heating and Cooling” Svend Frederiksen, Svend Werner

ISBN 978-91-44-08530-2
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6 Determining the flow rate
6.1 Principles of thermodynamics
6.1.1 General

The nominal heat or cooling load specifies the thermal energy power required at the measuring point in

the (projected) application.

The maximum thermal energy released or absorbed by a thermal conveying medium in a heating or

cooling circuit is calculated as follows:
Q= kV⋅⋅θθ− (1)
( )
where
is the thermal energy power, e.g. kW;
is the flow rate of the thermal conveying medium, in m /h;
k is the thermal coefficient, in kWh/m K;
θ is the design temperature in inlet, in °C;
θ is the design temperature in outlet, in °C.
Convert the formula to calculate the flow rate for the design case.
V= (2)
k⋅θθ−
( )
6.1.2 Total maximum power for heating or cooling

Add the outputs specified in Clause 5 to calculate the total thermal energy power.

QQ= (3)
tot
i=1
where
 is the total thermal energy power, in kW;
tot
is the standard thermal load, in kW;
is the thermal power for hot water heating, in kW;
 

NOTE If using priority control, use only the larger value, either Q or Q .

1 2
is the thermal energy power for ventilation and air conditioning systems, in kW;
is the thermal energy power for engineering purposes, in kW.
For cooling systems, the thermal load has to be added the same way (identical).
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6.1.3 Inlet and outlet temperature

The difference between inlet and outlet temperatures is the temperature difference.

∆=Θθ −θ K (4)
inlet outlet
 

In general, the inlet temperature of the heating or cooling medium is regulated by the outside

temperature and the outlet temperature is based on the design and operating mode of the heating system.

6.1.4 Thermal coefficient

The thermal coefficient k shall be determined according to prEN 1434-1:2020. For example, with

θ = 100 °C, θ = 50 °C the approximate value of 1,15 [kWh/(m K)] can be expected for outlet meters

inlet outlet
and 1,12 [kWh/(m K)] for inlet meters.
7 Selecting a flow sensor for a thermal energy meter

Because the design case described above occurs only for a few days of the year, a flow sensor shall be

selected so that it ensures that the smallest possible deviation occurs over the whole range of the year.

The range of the most frequent flow values (main operation range) at the measuring point is the deciding

factor for selecting the flow sensor.

The operating range of the flow sensor shall be within the approved range which is spread between the

smallest flow q and the nominal flow q .
i p
A flow sensor shall be selected to fulfil all the following criteria:

— the nominal flow q of the flow sensor is as close as possible to the calculated flow rate;

— the minimum flow q of the flow sensor is smaller than/equal to the minimum flow of the thermal

energy circuit;

— the maximum flow q of the flow sensor is reserved for short term overload (1 hour per day; 200

hours per year) in the thermal energy circuit.

If the minimum flow rate of the thermal energy circuit is not covered by the minimum flow q of the flow

sensor, it shall be checked whether a smaller flow sensor will cover the design case better.

To achieve the minimum flow rate of the thermal energy circuit, a flow sensor with a higher dynamic

range, q /q , shall be selected.
p i
The nominal flow q shall not be exceeded when selecting the flow sensor.

Selecting a flow sensor may be easier if technical measures are taken to reduce the fluctuation range of

the flow.

When selecting a flow sensor statutory regulations and standards, such as EN 1434, the operating

conditions, the manufacturer’s installation instructions and nationally applicable requirements shall all

be considered.

The nominal pressure level (PN/PS) of the flow sensor shall correspond to the pressure class at the

measuring point. In praxis the average pressure should be well below PN.

The permissible temperature range of the flow sensor shall comply with the temperature range of the

thermal conveying medium as well as the ambient temperature at the measuring poin

...

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