prEN 12976-2

SLOVENSKI STANDARD
01-april-2012
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Thermal solar systems and components - Factory made systems - Part 2: Test methods
Thermische Solaranlagen und ihre Bauteile - Vorgefertigte Anlagen - Teil 2:
Prüfverfahren
Installations solaires thermiques et leurs composants - Installations préfabriquées en
usine - Partie 2: Méthodes d’essai
Ta slovenski standard je istoveten z: prEN 12976-2
ICS:
27.160 6RQþQDHQHUJLMD Solar energy engineering
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
DRAFT
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2012
ICS 27.160 Will supersede EN 12976-2:2006
English Version
Thermal solar systems and components - Factory made
systems - Part 2: Test methods
Installations solaires thermiques et leurs composants - Thermische Solaranlagen und ihre Bauteile - Vorgefertigte
Installations préfabriquées en usine - Partie 2: Méthodes Anlagen - Teil 2: Prüfverfahren
d'essai
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 312.

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

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other language
made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, 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 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 STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 12976-2:2012: E
worldwide for CEN national Members.

Contents Page
Foreword .4
Introduction .5
1 Scope .7
2 Normative references .7
3 Terms and definitions .7
4 Symbols and abbreviations .7
5 Testing .8
5.1 Freeze resistance .8
5.1.1 General .8
5.1.2 Systems using antifreeze fluid .8
5.1.3 Drain-back systems .8
5.1.4 Drain-down systems .9
5.1.5 Freeze protection and control functions combined .9
5.1.6 Other systems .9
5.2 Over temperature protection . 10
5.2.1 Purpose . 10
5.2.2 Apparatus . 10
5.2.3 Procedure . 10
5.2.4 Reporting requirements . 11
5.3 Pressure resistance . 11
5.3.1 Purpose . 11
5.3.2 Apparatus . 11
5.3.3 Safety precaution . 11
5.3.4 Procedure . 12
5.3.5 Reporting requirements . 12
5.4 Water contamination . 13
5.5 Lightning protection . 13
5.6 Safety equipment . 13
5.6.1 Safety valves . 13
5.6.2 Safety lines and expansion lines . 13
5.6.3 Blow-off lines . 13
5.7 Labelling . 13
5.8 Thermal performance characterisation . 14
5.8.1 Introduction . 14
5.8.2 Test procedure . 14
5.8.3 Prediction of yearly performance indicators . 15
5.9 Ability of solar-plus-supplementary systems to cover the load . 19
5.9.1 General . 19
5.9.2 Boundary conditions for auxiliary heating . 19
5.9.3 Boundary conditions for daily load . 20
5.9.4 Determination of the ability to cover the maximum daily load by means of testing the
system . 20
5.9.5 Determination of the ability to cover the maximum daily load by means of numerical
simulations . 21
5.10 Reverse flow protection . 21
5.11 Electrical safety. 21
Annex A (normative) Thermal performance presentation sheet . 22
Annex B (normative) Reference conditions for performance prediction . 24
B.1 General . 24
B.2 Pipe diameter and insulation thickness . 26
B.3 Calculation of cold water temperature at reference location. 27
Annex C (informative) Extreme climate test procedure for the assessment of the frost resistance
of solar DHW systems with outdoor storage tank or systems using heat transfer fluid with
the risk of freezing . 29
C.1 Indoor and outdoor test procedure for assessment of the frost resistance of solar DWH
systems with outdoor storage tank or system using heat transfer fluid with the risk of
freezing . 29
C.1.1 Objective and applicability . 29
C.1.2 Apparatus and mounting of the system . 29
C.1.3 Test procedure . 30
 Test conditions — . 31
C.1.4 Determination of the test conditions for freezing period . 31
C.1.5 Results . 31
C.2 Indoor test procedure for assessment of the reliability of solar DWH systems in respect
of overheating protection . 32
C.2.1 Objective and applicability . 32
C.2.2 Apparatus and mounting of the system . 32
C.2.3 Test procedure . 34
C.2.4 Test conditions . 35
C.2.5 Results . 36
Annex D (informative) Ageing test for thermostatic valves . 38
D.1 General . 38
D.2 Test arrangement . 38
D.3 Test Procedure . 39
D.4 Results . 39
Annex E (informative) Lightning protection test for solar heating systems . 40
E.1 Field of application . 40
E.2 Purpose . 40
E.3 Requirements . 40
E.4 Apparatus . 41
E.5 Test procedure . 41
E.5.1 Test conditions . 41
E.5.2 Solar heating system installation . 41
E.5.3 Separation distance S . 41
t
E.5.4 Size of the bonding cable or strip . 42
E.5.5 Bridging between tank and supports . 42
E.5.6 Bridging between collectors and supports . 42
E.5.7 Bridging between collectors and tank . 42
E.5.8 Connecting terminal with Lightning Protection System (LPS) . 42
E.5.9 Metal sheets covering parts of the solar heating system . 42
E.5.10 Heating effects due to lightning currents . 42
E.5.11 Mechanical durability due to lightning mechanical loads . 42
E.6 Report . 43
E.7 Conclusions . 43
Annex F (informative) Lightning Protection testing sheet . 44
Bibliography . 48

Foreword
This document (prEN 12976-2:2012) has been prepared by Technical Committee CEN/TC 312 “Thermal solar
systems and components”, the secretariat of which is held by ELOT.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 12976-2:2006.
Introduction
Drinking water quality
In respect of potential adverse effects on the quality of water intended for human consumption, caused by the
product covered by this standard:
a) This standard provides no information as to whether the product may be used without restriction in any of
the Member States of the EU or EFTA;
b) It should be noted that, while awaiting the adoption of verifiable European criteria, existing national
regulations concerning the use and/or the characteristics of this product remain in force.
Factory Made and Custom Built solar heating systems
The standards prEN 12976-1, prEN 12976-2, CEN/TS 12977-1, CEN/TS 12977-2, EN 12977-3, CEN/TS 12977-4
and CEN/TS 12977-5 distinguish two categories of solar heating systems: Factory Made solar heating systems
and Custom Built solar heating systems. The classification of a system as Factory Made or Custom Built is a
choice of the final supplier, in accordance with the following definitions:
Factory Made solar heating systems are batch products with one trade name, sold as complete and ready
to install kits, with fixed configurations. Systems of this category are considered as a single product and
assessed as a whole.
If a Factory Made Solar Heating System is modified by changing its configuration or by changing one or more
of its components, the modified system is considered as a new system for which a new test report is
necessary. Requirements and test methods for Factory Made solar heating systems are given in
prEN 12976-1 and prEN 12976-2.
Custom Built solar heating systems are either uniquely built, or assembled by choosing from an assortment
of components. Systems of this category are regarded as a set of components. The components are
separately tested and test results are integrated to an assessment of the whole system. Requirements for
Custom Built solar heating systems are given in CEN/TS 12977-1; test methods are specified in
CEN/TS 12977-2 and EN 12977-3.
Custom Built solar heating systems are subdivided into two categories:
 Large Custom Built systems are uniquely designed for a specific situation. In general HVAC engineers,
manufacturers or other experts design them.
 Small Custom Built systems offered by a company are described in a so-called assortment file, in
which all components and possible system configurations, marketed by the company, are specified. Each
possible combination of a system configuration with components from the assortment is considered as
one Custom Built system.
Table 1 shows the division for different system types:
Table 1 — Division for factory made and custom built solar heating systems
Factory Made Solar Heating Systems Custom Built Solar Heating Systems
(prEN 12976-1 & prEN 12976-2) (CEN/TS 12977-1, CEN/TS 12977-2 & EN 12977-3)
Integral collector-storage systems for domestic hot
Forced-circulation systems for hot water preparation
water preparation
and/or space heating, assembled using components
and configurations described in a documentation file
Thermosiphon systems for domestic hot water
(mostly small systems)
preparation
Uniquely designed and assembled systems for hot
Forced-circulation systems as batch product with
water preparation and/or space heating (mostly large
fixed configuration for domestic hot water preparation
systems)
NOTE 1 Forced circulation systems can be classified either as Factory Made or as Custom Built, depending on the
market approach chosen by the final supplier.
NOTE 2 Both Factory Made and Custom Built systems are performance tested under the same set of reference
conditions as specified in Annex B of the present standard and CEN/TS 12977-2:2010, Annex A. In practice, the instal-
lation conditions may differ from these reference conditions.
NOTE 3 A Factory Made system for domestic hot water preparation may have an option for space heating, however
this option should not be used or considered during testing as a Factory Made system.
1 Scope
This European Standard specifies test methods for validating the requirements for Factory Made Thermal
Solar Heating Systems as specified in prEN 12976-1. The standard also includes two test methods for thermal
performance characterization by means of whole system testing.
2 Normative references
The following referenced documents are indispensable for the application of this European Standard. For
dated references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 12975-2:2006, Thermal solar systems and components — Solar collectors — Part 2: Test methods
prEN 12976-1:2012, Thermal solar systems and components — Factory made systems — Part 1: General
requirements
CEN/TS 12977-2:2010, Thermal solar systems and components — Custom built systems — Part 2: Test methods
EN 60335-1, Household and similar electrical appliances — Safety — Part 1: General requirements
(IEC 60335-1)
EN 60335-2-21, Household and similar electrical appliances — Safety — Part 2-21: Particular requirements
for storage water heaters (IEC 60335-2-21)
EN ISO 9488:1999, Solar energy — Vocabulary (ISO 9488:1999)
ISO 9459-1:1993, Solar heating — Domestic water heating systems — Part 1: Performance rating procedure
using indoor test methods
ISO 9459-2:1995, Solar heating — Domestic water heating systems — Part 2: Outdoor test methods for
system performance characterization and yearly performance prediction of solar-only systems
ISO 9459-5:2007, Solar heating — Domestic water heating systems — Part 5: System performance
characterization by means of whole-system tests and computer simulation
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN ISO 9488:1999 and
prEN 12976-1:2012 apply.
4 Symbols and abbreviations
Q net auxiliary energy demand of a solar heating system delivered by the auxiliary heater to the
aux, net
store or directly to the distribution system (see 5.8.3.2)
Q heat demand
d
Q energy delivered at the outlet of the solar heating system
L
Q parasitic energy (electricity) for the collector loop pump(s) and control unit
par
H hemispherical solar irradiation in the collector plane
c
Q store heat loss
l
Q heat diverted from the store as active overheating protection, if any
ohp
Q heat delivered by the collector loop to the store
sol
5 Testing
5.1 Freeze resistance
5.1.1 General
The following checks are given to ensure that the protective antifreezing provisions are operating properly.
There are many possible forms of protective provisions, and the testing authority shall first identify which
method has been employed.
The provision shall then be checked in accordance with the appropriate section of the following list (see 5.1.2
to 5.1.6) in accordance with the manufacturer’s recommendations.
5.1.2 Systems using antifreeze fluid
The system components which are exposed to low ambient temperature are filled with an antifreeze fluid,
usually a glycol/water mixture, having a low enough freezing point.
For these systems, no freezing test is performed. However, if no sufficient data is available on the freezing
point of the antifreeze fluid, the freezing point shall be measured and checked against the minimum system
temperature as given by the manufacturer.
NOTE In general, the minimum allowed temperature of the system is equal to the freezing point of the antifreeze fluid.
If the concentration of some antifreeze fluids - like glycol’s - exceeds a certain limit, they can freeze without damaging the
system. In this case the minimum allowed temperature can be lower than the freezing point of the antifreeze fluid.
Check the freezing point by measuring the glycol concentration (e.g. using a portable refractometer) before
and after the over temperature protection test (5.2). The freezing point shall not differ more than 2 K.from the
value recommended by the manufacturer in agreement with the local climate (minimum expected air
temperature, radiative cooling of the collectors).
The composition of the fluid shall be checked to see whether it is in accordance with the manufacturer’s
specifications.
5.1.3 Drain-back systems
The fluid in the system components, which are exposed to low ambient temperature, is drained into a storage
vessel for subsequent reuse when freezing danger occurs.
The collector loop piping should be in accordance with the manufacturer’s recommendations in the installer
manual and if there is no instruction, according to reference conditions given in Annex B.
Filling may be observed from the pressure gauge or from water level indicator. Switch the pump on, and
observe the pressure gauge or water level indicator. If the system does not include a pressure gauge or level
indicator, other means for checking filling provided by the manufacturer shall be used in accordance with the
instruction manual.
Drain-back may be observed from the decreasing reading of the pressure gauge or water level indicator.
Switch the pump OFF, and observe the pressure gauge or water level indicator. If the system does not include
a pressure gauge or level indicator, other means for checking drain-back provided by the manufacturer shall
be used in accordance with the instruction manual.
A system in which components and/or piping are subject to damage by freezing shall have the proper fittings,
pipe slope and collector design to allow for manual gravity draining and air filling of the affected components
and piping. Pipe slope for gravity draining shall be as the manufacturer recommendation or shall have a
minimum 2 cm vertical drop for each meter of horizontal length. This also applies to any header pipes or
absorber plate riser tubes internal to the collector.
5.1.4 Drain-down systems
The fluid in the system components, which are exposed to low ambient temperature, is drained and run to
waste when freezing danger occurs.
To perform checks of the drain-down function the collector loop piping should be in accordance with the
manufacturer’s recommendations in the installer manual and if there is no instruction, according to reference
conditions given in Annex B.
In most cases the systems are equipped with a drain-down valve at the bottom and a vacuum relief valve at
the top of the fluid circuit.
The proper opening and closing of the vacuum relief valve shall be checked during drain-down operation and
after re-filling the system.
If there is a solenoid drain valve independent of the control unit, simulate the opening temperature.
If there is a non-electrically operated freeze-protection valve, a check can be made using a freezing spray.
The temperature-sensing element shall be sprayed. The measured temperature of the valve opening is to be
compared with the nominal value given by the manufacturer. It is important that the sensing part of the freeze-
protection valve be properly placed.
If the system uses an electrically operated freeze-protection valve, drain down shall be checked while
interrupting the power.
The drain-down rate shall be measured (e.g. by using a vessel and a stop-watch) and documented during
drain-down operation.
5.1.5 Freeze protection and control functions combined
For systems where the freeze-protection and control functions are combined, the control unit shall be checked
as follows:
Set the simulated temperature of the freeze-protection sensor to a value deactivating the freeze protection.
Decrease the simulated temperature slowly. Measure the temperature T of the related
FP (freeze-protection)
actuator. Compare it with the nominal value given by the manufacturer.
5.1.6 Other systems
For all other systems, the pump control system, drain-down valve or any other freeze protection device or
system shall be checked to the manufacturer's specification and the minimum allowed temperature specified
by the manufacturer.
For ICS systems, or other SDHW systems with the tank placed outside, special frost resistance tests should
be carried out, as described in C.1.
5.2 Over temperature protection
5.2.1 Purpose
The purpose of this test is to determine whether the solar water heating system is protected against damage
and the user is protected from scalding hot water delivery after a period of no hot water draw and failure of
electrical power.
5.2.2 Apparatus
The following apparatus is required:
a) A pyranometer having the minimum characteristics specified in EN 12975-2, to measure the total short
wave radiation from both the sun and the sky or the short wave radiation from a solar simulator lamp if the
test is to be conducted inside a solar simulation chamber.
b) Equipment to measure the temperature, flow rate and volume of hot water drawn from the system.
c) An outdoor or an indoor test stand for installing the solar hot water system with the collector array at the
manufacturer's specified angle of inclination.
d) A temperature and pressure controlled water supply within the range of 5°C to 25 ºC and 200kPa to
600 kPa or the manufacturer's maximum working pressure whichever is less.
This test may be conducted using a solar simulator or outdoors.
5.2.3 Procedure
The system, both as described in the installation manual and as installed on the test facility, shall be first
checked on overheating safety, e.g. if safety valves and other overheating protection devices are present and
installed at the right place, if there are no valves between components and relief valves etc. For systems
containing antifreeze fluids, it shall be checked whether sufficient precautions have been taken to prevent the
antifreeze fluid from deterioration as a result of high temperature conditions (See also 5.6).
Furthermore, if non-metallic materials are used in any circuit, the highest temperature in the circuit shall be
measured during the over temperature protection test, for use in the pressure resistance test.
The procedure of testing shall be as follows:
a) Assemble the solar water heating system according to the installation instructions with the collector array
oriented towards solar noon for the outdoor test, or the simulator lamp may be adjusted to normal
incidence for the indoor test.
b) Charge the system from the water supply and, for pressurized storage tanks, maintain the water supply
pressure.
c) Energize the system as per installation instructions.
d) (i) For the outdoor test, operate the system for a minimum of 4 consecutive days without any hot water
withdrawal and until the collector array has been subjected to 2 consecutive days in which the solar
irradiation on the plane of the collector array has exceeded 20 MJ/m per day and the ambient
temperature has exceeded 20 ºC during solar noon.
(ii) For the indoor test, operate the system without any hot water withdrawal at an ambient temperature of
(25 ± 2) ºC and a minimum solar lamp irradiance of 1000 W/m at the plane of the collector array,
measured and with a uniformity as specified in ISO 9459-1:1993, 6.3.1.2 for a 5 h period or until the
collector array drains.
e) (i) For the outdoor test, disconnect all electrical power (if there is any) to the system and continue to
operate the system until the solar irradiation on the plane of the collector array has exceeded 20 MJ/m
per day or until the load circuit drains.
(ii) For the indoor test, disconnect all electrical power to the system and subject the system to a solar lamp
irradiance of 1000 W/m at the plane of the collector array for an additional 4 h or until the collector array
drains.
f) Immediately begin to withdraw a volume of water greater than the total volume of water in the system at a
-4 -5 3
rate of 2x10 ± 3x10 m /s (10 ± 1 l/min.)
5.2.4 Reporting requirements
The following results shall be reported:
a) The make and model identification of the system including ancillary scald and over temperature protection
devices fitted.
b) The inclination of the collector array.
c) A record of temperature of the hot water withdrawn from the system versus time and the total volume of
water withdrawn. Note the presence of steam if observed.
d) Details of the condition of the system and individual components following the test or any failure modes
during the test with particular regard to any defects which may affect the serviceability of the system such
as the swelling of pipes and components or fluid leakages.
5.3 Pressure resistance
5.3.1 Purpose
The purpose of this test is to evaluate hydraulic pressure rating of all components and interconnections of a
solar water heating system when installed according to the manufacturer's instructions.
5.3.2 Apparatus
The apparatus shall consist of the following:
a) suitable platform and support structure for installation of the system
b) pressure regulated hydraulic pressure source
c) pressure gauge suitable to determine the test pressure to within 5 %
d) bleed valve
e) isolation valve
5.3.3 Safety precaution
An explosion safe enclosure is recommended when testing systems that have an integral expansion space or
tank that contains entrapped air.
5.3.4 Procedure
The system, both as described in the installation manual and as installed on the test facility, shall be first
checked on pressure safety, e.g. if safety valves and other overheating protection devices are present and
installed at the right place, if there are no valves between components and relief valves etc.
The duration of the test is 15 min. If a non-metallic material is used in any circuit, this procedure has to be
applied after performing the “over Temperature protection” test (see 5.2).
a) Install the solar water heating system on the test platform in accordance with the manufacturer's
instructions.
b) Disable the pressure relief valves, if applicable, to prevent their opening during testing.
c) Connect the isolation valves to the (lower) fill ports of each circuit of the system
d) Fill all circuits in the order described in the manufacturer’s installer manual using the required fluid for
each circuit. If no information about the fill procedure is provided in the manual, the inner circuits should
be filled first. After filling the upper port of each circuit should remain open to provide pressure balance
with the ambient pressure.
e) Perform the pressure tests of the circuits of the system in the same order as they have to be pressurized
(or installed) according to the manufacturer’s installer manual. If no installation order is given by the
manufacturer, perform the pressure tests of the internal heat transfer loops (and other internal vessels)
first.
f) For testing of each independent loop follow the steps listed below:
1) Connect the bleed valve and pressure gauge to the (upper) drain port of the heat transfer loop.
2) Connect the hydraulic pressure source to the fill port of the tested heat transfer circuit.
3) Bleed all air, as far as possible, out of the loop through the bleed valve at the drain port.
4) Apply a hydraulic pressure equal to 1.5 times the manufacturer's stated maximum individual working
pressures.
5) Isolate the pressure source by closing the isolation valve and record the readings of the pressure
gauge at the beginning and end of the next 15 min interval.
6) Release the pressure through the bleed valve and record any visible permanent deformation and heat
transfer fluid leakage from system components and interconnections.
7) Disconnect the hydraulic pressure source from the fill port, the bleed valve and pressure gauge from
the drain port and leave the circuit filled and opened at the ambient pressure.
8) Repeat the steps 1)-7) until all circuits have been tested.
g) Empty all circuits in the reversed fill order or according to emptying instructions contained in the
manufacturer’s installer manual if present.
h) Disconnect all isolation valves from the system.
5.3.5 Reporting requirements
Report the maximum test pressures applied, the pressure readings at the beginning and end of the 15 min
test intervals and any visible permanent deformation or leakage from system components and
interconnections. Note if the applied test pressures are lower than 1,5 times the manufacturer's stated
maximum working pressure.
The test may be considered as passed, if the pressure drop during the test period does not exceed more than
5 % of the test pressure.
5.4 Water contamination
Check if the in the documentation for the installer the manufacturer includes instructions for the installation of
the adequate means for preventing backflow from all circuits to drinking main supplies.
5.5 Lightning protection
Annexes E and F give information to assist manufacturers in meeting the requirements given in IEC 61024-1.
5.6 Safety equipment
5.6.1 Safety valves
Check the system documentation to verify that each collector circuit or group of collector circuits is fitted with
at least one safety valve.
Check the specification of the safety valves, whether the materials conform to:
– resist the temperature conditions which it is exposed to, especially the highest temperature that can occur.
– resist the heat transfer medium.
Check whether the size of the safety valve is correct in order that it can release highest flow of hot water or
steam that can occur. The dimension of the safety valve(s) shall be proved by suitable means.
Check whether the temperature of the heat transfer medium at the release pressure of the safety valve
exceeds the maximum allowed temperature of the heat transfer medium.
To check the applicability of the specified maintenance frequency of a thermostatic valve, the ageing test for
thermostatic valves should be carried out, as described in Annex D.
5.6.2 Safety lines and expansion lines
Check the system documentation to verify that safety and expansion lines, if any, cannot be shut-off.
Check the internal diameter of the expansion line, if any, to verify if, for the highest flow of hot water or steam
that can occur, at no place in the collector loop the maximum allowed pressure is exceeded due to the
pressure drop in these lines. The dimension of the safety line and expansion line shall be proved by suitable
means.
Check the system documentation to verify that the expansion line and the safety line, if any, are connected
and laid in such a way that any accumulation of dirt, scale or similar impurities are avoided.
5.6.3 Blow-off lines
Check the hydraulic scheme and system documentation to verify that the blow-off lines, if any, cannot freeze
up and that no water can accumulate within these lines. The orifices of the blow-off lines shall be arranged in
such a way that any steam or heat transfer medium issuing from the safety valves does not cause any risk for
people, materials or environment.
5.7 Labelling
Check the Marking plate or Label of the Solar heating system and examine if all items of the labelling list are
completed (as specified in 4.7 of prEN 12976-1:2012).
5.8 Thermal performance characterisation
5.8.1 Introduction
In this subclause the methods for performance testing are described. The thermal performance of the system
shall be characterised as described in 5.8.2 and presented as specified in 5.8.3.
NOTE The performance of a solar heating system depends on the individual installation and actual boundary conditions.
With regard to the heat losses of the store besides deficits in the thermal insulation, badly designed connections can increase
the heat loss capacity rate of the store due to natural convection that occurs internally in the pipe. In order to avoid this effect
the connections of the pipes should be designed in such a way that no natural convection inside the pipe occurs. This can
e.g. be achieved if the pipe is directly going downwards after leaving the store or by using a siphon.
5.8.2 Test procedure
One of the following test methods shall be used, as described in Table 2.
a) Test method in accordance with ISO 9459-2.
This test method may be applied on “solar only” or “preheat systems”.
b) Test method in accordance with ISO 9459-5.
This test method may be applied on all types of systems.
Table 2 — Selection of the performance test method
Test method Solar-plus-supplementary Solar-only and preheat
*)
systems
systems
ISO 9459-2 (CSTG) No Yes
ISO 9459-5 (DST) Yes Yes
NOTE 1 Some systems have allowances for variations in the installation instructions that may affect the performance of
the system. In cases where the circumstances are not uniquely defined by the Reference Conditions given in Annex B, the
most unfavourable conditions should be chosen for testing and reporting of the system performance. For example,
systems without forced circulation should be tested with the lowest position of the storage above the collector and the
longest pipe length between collector and storage specified by the manufacturer.
NOTE 2 In October 1999, the EU–SMT project team “Bridging the Gap” reported on the comparability between CSTG
(ISO 9459-2) and DST (ISO/DIS 9459-5) and conversion factors were successfully established. The relation between the
performance predictions of both test methods is given by:

The ‘a-values’ are represented in Table 3:
Table 3 — Parameter a values for different load volumes
Type of system Condition a [[[[
a
a
Forced circulation 1,004 0,004
V ≥ V
load store
Thermosyphon system All V 1,056 0,004
load
ICS system All V 1,037 0,003
load
a
In the case V < V (forced circulation systems), the determined 'a-values' are higher. This indicates a stronger tendency for
load store
overestimation of the DST test method.

5.8.3 Prediction of yearly performance indicators
5.8.3.1 General
NOTE  In the following, performance indicators for solar heating systems for hot water prepara
...