ENV 12977-2:2001

SLOVENSKI STANDARD
SIST ENV 12977-2:2002
01-november-2002
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Thermal solar systems and components - Custom built systems - Part 2: Test methods
Thermische Solaranlagen und ihre Bauteile - Kundenspezifisch gefertigte Anlagen - Teil
2: Prüfverfahren
Installations solaires thermiques et leurs composants - Installations assemblées a façon -
Partie 2: Méthodes d'essais
Ta slovenski standard je istoveten z: ENV 12977-2:2001
ICS:
27.160 6RQþQDHQHUJLMD Solar energy engineering
91.140.10 Sistemi centralnega Central heating systems
ogrevanja
91.140.65 Oprema za ogrevanje vode Water heating equipment
SIST ENV 12977-2:2002 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ENV 12977-2:2002

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SIST ENV 12977-2:2002
EUROPEAN PRESTANDARD
ENV 12977-2
PRÉNORME EUROPÉENNE
EUROPÄISCHE VORNORM
April 2001
ICS 27.160
English version
Thermal solar systems and components - Custom built systems
- Part 2: Test methods
Installations solaires thermiques et leurs composants - Thermische Solaranlagen und ihre Bauteile -
Installations assemblées à façon - Partie 2: Méthodes Kundenspezifisch gefertigte Anlagen - Teil 2: Prüfverfahren
d'essais
This European Prestandard (ENV) was approved by CEN on 12 March 2001 as a prospective standard for provisional application.
The period of validity of this ENV is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the ENV can be converted into a European Standard.
CEN members are required to announce the existence of this ENV in the same way as for an EN and to make the ENV available promptly
at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the ENV) until the final
decision about the possible conversion of the ENV into an EN is reached.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2001 CEN All rights of exploitation in any form and by any means reserved Ref. No. ENV 12977-2:2001 E
worldwide for CEN national Members.

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SIST ENV 12977-2:2002
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ENV 12977-2:2001
Contents
Page
Foreword. 2
Introduction. 2
1 Scope . 5
2 Normative references. 6
3 Terms and definitions. 7
4 Symbols and abbreviations. 7
5 System classification . 9
6 Test methods. 9
7 Optional performance test of small custom built solar heating systems . 15
8 Performance test report. 23
Annex A (normative) Reference conditions for performance prediction . 24
Annex B (normative) Testing of solar loop controllers with temperature sensors . 29
Annex C (informative) Short-term system testing. 35
Annex D (informative) Long-term monitoring. 47
Bibliography . 49
Foreword
This European Prestandard has been prepared by Technical Committee CEN/TC 312 "Thermal
solar systems and components", the secretariat of which is held by ELOT.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to announce this European Prestandard: Austria, Belgium,
Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,
Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United
Kingdom.
The annexes A and B are normative. The annexes C and D are informative.
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 Prestandard it should be noted that:
a) This Prestandard provides no information as to whether the product may be used without
restriction in any of the Member States of the EU or EFTA;

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ENV 12977-2:2001
b) 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 EN 12976-1 well as EN 12976-2 and the Prestandards ENV 12977-1 to ENV
12977-3 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
EN 12976-1 and EN 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 ENV 12977-
1, test methods are specified in ENV 12977-2 and ENV 12977-3. Custom Built solar heating
systems are subdivided into two categories:

  are uniquely designed for a specific situation. In general
Large Custom Built systems
HVAC engineers, manufacturers or other experts design them.

  offered by a company are described in a so-called
Small Custom Built systems
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
(EN 12976-1, -2) (ENV 12977-1, -2, -3)
Integral collector-storage systems for Forced-circulation systems for hot water preparation
domestic hot water preparation and/or space heating, assembled using components
and configurations described in a documentation file
Thermosiphon systems for domestic
hot water preparation (mostly small systems)
Forced-circulation systems as a batch Uniquely designed and assembled systems for hot
product with fixed configuration for water preparation and/or space heating
domestic hot water preparation (mostly large 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.

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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 EN 12976-2:2000 and annex A of ENV 12977-2:2001. In practice,
the installation conditions may differ from these reference conditions.
Test methods and procedures for the analysis of large custom built solar heating systems
Quality assurance is of primary importance for large custom built systems. The total investment
cost for such systems is higher than for smaller ones, although the specific investment cost (i.e.,
per m² collector area) is lower. In several European countries, the potential of large custom
built systems from the point of view of conventional energy savings is much larger than for
smaller ones. Moreover, the return-on-investment is in many cases more favorable for large
systems than for small ones. Hence, both the purchasers of large custom built systems and the
governments are interested in efficient, reliable and durable systems, the thermal performance
of which may be accurately predicted, checked and supervised.
The test methods in this Prestandard provide a means of verifying the compliance of large
custom built systems with the requirements in ENV 12977-1.
NOTE 3 Within the framework of the EU ALTENER Programme the project ”Guaranteed Solar Results” (GSR)
is addressing similar objectives in respect of quality assurance (see 7, 8). Similar procedures and monitoring
equipment are used as described in annexes C and D. It might be necessary to update the informative annexes C
and D later on in a revision of this Prestandard when more experience is available, in particular from the GSR
project.
As large custom built systems are by definition unique systems, only general procedures on
how to check and supervise them may be given. An additional difficulty in the formulation of
procedures is the fact that they have to be adapted to the dimension of the large custom built
system considered, which may vary from typically 30 to 30000 m² of collector area. Therefore,
several possible levels of analysis are included (annexes C and D).
The objective of the two short-term system tests presented in annex C is the characterization of
system performance and/or the estimation of the ability of the system to deliver the energy
claimed by the designer. In principle, two approaches for short-term system testing are referred
to in this Prestandard:
a) A simplified check of short-term system performance, carried out by intercomparison of
the measured solar system heat gain with the one predicted by simulation, using the actual
weather and operating conditions as measured during the short-term test.
b) A short-term test for long-term system performance prediction. The performance of the
most relevant components of the solar heating system is measured for a certain time period
while the system is in normal operation. More detailed measurements encompass a) energy
gain of collector array(s) and b) energy balance over storage vessel(s). Intercomparison of
the observed and simulated energy quantities provides the indirect validation of collector
and storage design parameters. The measured data within the collector array are also used
for direct identification of the collector array parameters. As far the component parameters
are verified, the long-term prediction of the system gain as well as the detection of possible
sources of system malfunctioning are possible.

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Annex D describes a procedure for long-term monitoring as a part of the supervision of a large
custom built solar heating system. The objectives of supervision may be: a) the early
recognition of possible failures of system components, in order to get the maximum benefit
from the initial solar investment as well as to minimize the consumption of non-solar energy
and the resulting environmental impact; b) the measurement of system performance (solar gains
or other system indicators), if requested by a contractual clause, e.g. guaranteed results. The
long-term monitoring in annex D is limited to the solar energy specific aspects, especially to
the determination of the solar contribution to the total heat load. Instrumentation used in the
long-term monitoring should be an integrating part of the system, a part included from the very
beginning of the design process. If adequately foreseen, it may also be used for system
adjustment at start time.
1 Scope
This European Prestandard applies to small and large custom built solar heating systems with
liquid heat transfer medium for residential buildings and similar applications, and gives test
methods for verification of the requirements specified in ENV 12977-1.
This Prestandard includes also a method for thermal performance characterization and system
performance prediction of small custom built systems by means of component testing and
system simulation.
Furthermore, the Prestandard contains methods for thermal performance characterization and
system performance prediction of large custom built systems.
This European Prestandard applies to the following types of small custom built solar heating
systems:

systems for domestic hot water preparation only;

systems for space heating only;

systems for domestic hot water preparation and space heating.
This European Prestandard applies to large custom built solar heating systems, primarily to
solar preheat systems, with one or more storage vessels, heat exchangers, piping and automatic
controls and with collector array(s) with forced circulation of fluid in the collector loop.
This Prestandard does not apply to:

systems with a store medium other than water (e.g. phase-change materials);

systems for space heating with a distribution fluid other than water for the space heating
subsystem (e.g. air systems);

small custom built systems with a circulation line entering any store having a feedback on
the solar heated store.
Principally, systems with circulation line may be tested in accordance to the methods
described in this Prestandard, if the connecting port for the circulation line is kept closed
during the tests. This should, however, stated in the test report.

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thermosiphon systems;

integral collector-storage (ICS) systems.
The test procedure of annex C cannot be applied to solar heating systems with concentrating
collectors.
NOTE  The two test methods presented in annex C (”Short-term system testing”) have only been validated, so far,
two laboratories, at the Danish Technological Institute DTI and at the Chalmers University of Technology
Göteborg (9, 14). DTI is confident that the procedures are promising and very efficient. However, the full
verification and a round robin test within Europe are urgently needed.
2 Normative references
This European Prestandard incorporates, by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions
of any of these publications apply to this European Prestandard only when incorporated in it by
amendment or revision. For undated references the latest edition of the publication referred to
applies (including amendments).
EN 307:1998 Heat exchangers — Guidelines to prepare installation, operating and
maintenance instructions required to maintain the performance of each
type of heat exchanger
EN 806-1 Specifications for installations inside buildings conveying water for
human consumption – Part 1: General
EN 809 Pumps and pump units for liquids – Common safety requirements
EN 1151 Pumps - Rotodynamic pumps - Circulation pumps having an electrical
effect not exceeding 200 W for heating installations and domestic hot
water installations — Requirements, testing, marking
EN 1717 Protection against pollution of potable water in drinking water
installations and general requirements of devices to prevent pollution
by backflow
ENV 1991-2-3 Eurocode 1- Basis of design and actions on structures – Part 2-3:
Actions on structures - Snow loads
ENV 1991-2-4 Eurocode 1- Basis of design and actions on structures – Part 2-4:
Actions on structures - Wind loads
prEN 12897:1997 Water supply – Specification for indirectly heated unvented (closed)
hot water storage systems
EN 12975-1 Thermal solar systems and components – Solar collectors –Part 1:
General requirements
EN 12975-2:2001 Thermal solar systems and components – Solar collectors –Part 2: Test

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ENV 12977-2:2001
methods
EN 12976-1:2000 Thermal solar systems and components – Factory made systems –
Part 1: General requirements
EN 12976-2:2000 Thermal solar systems and components – Factory made systems –
Part 2: Test methods
ENV 12977-1:2001 Thermal solar systems and components – Custom built systems –
Part 1: General requirements
ENV 12977-3 Thermal solar systems and components – Custom built systems –
Part 3: Performance characterization of stores for solar heating systems
EN 60335-1:1994 Safety of household and similar electrical appliances – Part 1: General
requirements (IEC 60335-1:1991 modified)
EN 60335-2-21:1999 Safety of household and similar electrical appliances – Part 2:
Particular requirements for storage water heaters
(IEC 60335-2-21:1997 + Corrigendum 1998, modified)
ISO 9459-5 Solar heating - Domestic water heating systems - Part 5: System
performance by means of whole system testing and computer
simulation
EN ISO 9488:1999 Solar energy– Vocabulary (ISO 9488:1999)
3 Terms and definitions
For the purposes of this Prestandard, the terms and definitions given in EN ISO 9488 and
ISO 9459-5 as well as EN 12975-1, EN 12976-1 and ENV 12977-1 apply.
4 Symbols and abbreviations

a algebraic constant for the determination of the collector heat loss coefficient
1
A collector reference area
c
C collector array heat capacity
c
f solar fraction
sol
G solar irradiance
G diffuse irradiance
d
G global irradiance (i.e. horizontal)
g
G hemispherical irradiance, e.g. on tilted plane
h
H hemispherical solar irradiation in collector plane
c
K incidence angle modifier

P power of the auxiliary heater
aux
P thermal power of the collector or collector array
c

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P circulation heat loss power
rc
 heat delivered by the collector loop to the store
Q
sol
net auxiliary energy demand of a solar heating system delivered by the auxiliary
Q
aux,net
heater to the store or directly to the heat distribution system (see 7.5.3)
Q energy delivered at the outlet of the solar heating system
L
Q heat demand
d
Q store heat losses
l
Q heat diverted from the store as active overheating protection, if any
ohp
Q parasitic energy (electricity) for the collector loop pump(s) and control unit
par

yearly average cold water temperature on reference location
average

collector ambient air temperature
c,amb
store ambient air temperature


S,amb

collector or collector array inlet/outlet fluid temperature
ci/co
mains water temperature


cw
desired hot water temperature


d

mean collector fluid temperature;
= (
+
) / 2
m m ci co

fluid temperature at circulation loop inlet
rci

fluid temperature at circulation loop outlet
rce
required temperature for sensor high-temperature resistance (see annex B)

req
store outlet fluid temperature


S
sensor temperature (see annex B)

sens

temperature for which controller operation starts/stops (see annex B)
start/stop
temperature of the storage tank (see annex B)


tank
 T*
reduced temperature of collector; T* = (
-
) /G
m c,amb h
(UA) heat transfer rate of a heat exchanger
hx
(UA) store heat loss rate
S
U overall heat loss coefficient of collector array
L
V demanded (daily) load volume
d
V store volume
S


V
 volume flow rate in collector loop
c


V volume flow rate in circulation loop
rc


V volume draw-off flow rate from storage

s
v surrounding air speed

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temperature difference


average amplitude of seasonal variations on reference location


amplit
 zero-loss collector efficiency (efficiency at T* = 0)
0

5 System classification
See clause 5 of ENV 12977-1:2001.
6 Test methods
Subsequent test methods refer to the requirements given in ENV 12977-1.
NOTE  The numbering of the following clauses is kept in direct correspondence to the numbering in ENV 12977-
1.
6.1 General
6.1.1 Suitability for drinking water
See EN 806-1.
6.1.2 Water contamination
For small custom built systems see EN 1717.
Large custom built systems: Check the hydraulic scheme or any other part of the documentation
of the system according to 6.7.3 of ENV 12977-1:2001. (See also the introduction about water
quality).
6.1.3 Freeze resistance
See 5.1 of EN 12976-2:2000
6.1.4 Overheating protection
6.1.4.1 Scald protection
If the temperature of the domestic hot water in the system can exceed 60 °C, check the design
plan or the system documentation to see whether the system is provided with an automatic cold
water mixing device or any other device capable for limiting the water temperature to 60 °C at
most.
6.1.4.2 Overheating protection of materials
Ensure by checking the hydraulic scheme and/or by calculation and taking into account the
most adverse conditions for the materials of all parts of the system, that the maximum
temperatures which may occur do not exceed the maximum permissible temperatures for the
respective materials.
NOTE  Both transients (high-temperature peaks of short duration) and stagnation of longer duration may create
adverse conditions for the respective material.

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6.1.5 Reverse flow prevention
Check the hydraulic scheme included in the documentation (see 6.7) to ensure that no
unintentional reverse flow will occur in any hydraulic loop of the system.
6.1.6 Pressure resistance
See prEN 12897:1997.
If any component of the system is not covered by prEN 12897:1997 or EN 12975-1, check the
technical data to see whether the component for the part of the system in which it is used will
withstand the lowest of the following pressures

1,5 times the manufacturer’s stated maximum working pressure

the manufacturer’s stated maximum test pressure
In addition, for large custom built systems only:
– Regarding safety valves, check the hydraulic scheme or any other part of the
documentation of the system according to 6.7.3 of ENV 12977-1:2001.
– Regarding pressure resistance, check whether the collector array can withstand short
and high pressure peaks. Calculate the highest pressure that can occur in the individual
loops in the system and compare it with the maximum allowed pressure of the
individual loops (see also NOTE 2 in 6.1.6 of ENV 12977-1:2001). Alternatively, an
experimental test with 1,3 times the maximum allowed pressure of each loop may be
applied.
6.1.7 Electrical safety
See EN 60335-1:1994 and EN 60335-2-21:1999.
6.2 Materials
Check the work certificates provided by the manufacturer whether the requirements on UV
radiation and weather resistance as well as on the choice of materials for the collector loop are
fulfilled. For small custom built systems this check shall in any case be performed, for large
ones as far as applicable.
6.3 Components and pipework
6.3.1 Collector and collector array
The collector shall be tested according to EN 12975-2.
In addition, the maximum disparity of the mass flow rate in parallel collector rows should be
calculated by means of the corresponding pressure drops.
6.3.2 Supporting frame
Check the calculation proving the resistance of the frame to snow and wind loads in accordance
with ENV 1991-2-3 and 1991-2-4.
6.3.3 Collector and other loops
The optional collector loop test comprises the following steps:

Determination of the nominal power needed by the collector loop pump

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Calculation of the highest heat power which can be delivered by the collector array
P :
c,max
P =  A G (1)
c,max 0 c ref
2
where G is the reference irradiance of 1000 W/m (for other symbols see clause 4).
ref

Check of the values calculated by formula (1) in comparison with the values listed in
Table 4 of ENV 12977-1:2001.
For other heat transfer loops, the nominal parasitic power of their pump(s) should be directly
compared with the calculated highest transmitted heat power, based on Table 4 of
ENV 12977-1:2001.
6.3.4 Circulation pump
See EN 809 and EN 1151.
6.3.5 Expansion vessel
For drain-back systems without a separate expansion vessel, check both by calculation and the
hydraulic scheme to see whether the drain-back facility is able to fulfil its additional task as an
expansion vessel.
6.3.5.1 Open expansion vessel
Check the volume and design of the open expansion vessel by calculation and by checking the
hydraulic scheme.
In addition, check the connection of the vessel to the atmosphere, the spill line and the
expansion lines on the hydraulic scheme.
6.3.5.2 Closed expansion vessel
For small custom built systems only: Check the fulfilment of the requirements given in 6.3.5.2
of ENV 12977-1:2001 by calculation and by visual check of the hydraulic scheme and
operating instruction.
6.3.6 Heat exchangers
Apart from the tests in compliance with EN 307:1998, check the design of the heat
exchanger(s) with respect to scaling or the availability of cleaning facilities.
In addition, the drop in system efficiency  induced by a heat exchanger in the collector loop
of a small custom built system should be estimated by formula (2):
a

Ac1
= 0 100 %
(2)

UA
( )
hx
where  and a are given from the collector performance test of EN 12975-2. For small
0 1
systems (UA) is delivered by the store performance test of ENV 12977-3 ((UA) to be chosen
hx hx
for fluid temperatures of 20 °C). For large systems  (UA) is taken from the heat exchanger
hx
performance data sheet provided by the manufacturer.
NOTE 1  In the latter case, since performance data of external heat exchangers (which are mostly used in large
custom built systems) are generally quite reliable, no additional measurements are needed.

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For heat exchangers in other loops (e.g., a load side heat exchanger), the mean temperature rise
on the primary side 
which is induced by the presence of the heat exchanger should be
estimated by calculation. The drop in efficiency may then be estimated by:
 = (a 
/G ) 100% (3)
1 ref
2
where the reference irradiance G is set to 1000 W/m .
ref
NOTE 2  More accurate calculation methods are given in  1. In special cases the thermal stratification in the
store should be taken into account, to obtain an accurate figure for the efficiency drop.
6.3.7 Store
With the exception of the heat loss rate, stores for drinking water shall be tested according to
clause 6 of prEN 12897:1997. For small custom built systems, this test applies in any case, for
large custom built systems as far as applicable.
In addition, for small custom built systems only:
- the performance of their hot water stores should be characterized according to
ENV 12977-3.
- the heat loss rate of these hot water stores, obtained from performance characterization
according to ENV 12977-3, should be compared with the requirements given in 6.3.7 of
ENV 12977-1:2001.
6.3.8 Pipework
Check the design plan, manufacturer’s works certificates and system documentation in respect
of design and material of pipes and fittings.
6.3.9 Thermal Insulation
Check the design plans and system documentation.
6.3.10 Control system
6.3.10.1 Controller
For small custom built systems only: The optional controller test is described in annex B.
6.3.10.2 Temperature sensors
The design plans and components shall be visually checked in respect of location, installation
and insulation of the sensors according to the requirements in 6.3.10.2 of ENV 12977-1:2001.
Additionally:

For small custom built systems: Test the sensor resistance to high temperature as
described in B.3. This test is, however, not necessary if a documentation delivered with
the sensor indicates that it can withstand 100 °C or stagnation conditions (whichever the
greatest) without altering by more than 1 K.

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For large custom built systems: Check the suitability of the temperature sensors in
respect of stagnation conditions or maximum temperatures in connection with the
quality declaration given by the suppl
...