ISO 9459-4:2013

INTERNATIONAL ISO
STANDARD 9459-4
First edition
2013-02-15
Solar heating — Domestic water heating
systems —
Part 4:
System performance characterization by
means of component tests and computer
simulation
Chauffage solaire — Systèmes de chauffage de l'eau sanitaire —
Partie 4: Caractérisation de la performance des systèmes au moyen
d'essais effectués sur les composants et par simulation sur ordinateur

Reference number
©
ISO 2013
©  ISO 2013
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Published in Switzerland
ii © ISO 2013 – All rights reserved

Contents Page
Foreword . iv
0  Introduction . v
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
4  Symbols, units and nomenclature . 3
5  Application . 6
6  Test method . 7
6.1  Introduction . 7
6.2  Component testing . 7
6.3  Water heater configuration for modelling . 9
7  Performance evaluation . 10
7.1  Annual task performance . 10
7.2  Weather data . 10
7.3  Thermal energy loads . 11
7.4  Thermostat set temperature . 11
7.5  Cold water inlet temperature . 11
7.6  Pump circulation control . 11
7.7  Simulation deck setup for modelling thermal stratification in storage tanks . 12
7.8  Piping configuration for solar water heaters . 13
7.9  Controllers . 14
7.10  Energy consumed for freeze protection . 14
7.11  Over-temperature control . 15
7.12  Modelling gas storage water heaters . 15
7.13  Modelling instantaneous gas water heaters . 16
7.14  Presentation of results . 17
7.15  Extension of simulation model for new products . 19
Annex A (normative) Water heater parameters . 20
Annex B (normative) Storage vessel performance . 34
Annex C (normative) Integral collector storage unit test method . 37
Annex D (normative) Corrections for effect of hail guards on solar collector efficiency . 41
Annex E (normative) PV powered DC pumps in solar water heating systems . 43
Annex F (normative) Heat exchanger test methods . 50
Annex G (normative) Reference conditions for testing and performance prediction . 58
Annex H (informative) Example simulation models . 63
Annex I (informative) Guidelines for equipment suppliers . 67
Annex J (informative) Guidelines for Certification Bodies . 68
Bibliography . 70

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 9459-4 was prepared by Technical Committee ISO/TC 180, Solar energy, Subcommittee SC 4,
Systems — Thermal performance, reliability and durability.
ISO 9459 consists of the following parts, under the general title Solar heating — Domestic water heating
systems:
 Part 1: Performance rating procedure using indoor test methods
 Part 2: Outdoor test methods for system performance characterization and yearly performance prediction
of solar-only systems
 Part 4: System performance characterization by means of component tests and computer simulation
 Part 5: System performance characterization by means of whole-system tests and computer simulation
iv © ISO 2013 – All rights reserved

0 Introduction
ISO 9459 has been developed to help facilitate the international comparison of solar domestic water heating
systems. Because a generalized performance model which is applicable to all systems has not yet been
developed, it has not been possible to obtain an international consensus for one test method and one
standard set of test conditions. It has therefore been decided to promulgate the currently available simple test
methods while work continues to finalize the more broadly applicable procedures. The advantage of this
approach is that each part can proceed on its own.
0.1 General
ISO 9459 is divided into four parts within three broad categories, as described below.
0.2 Rating test
ISO 9459-1, Solar heating — Domestic water heating systems — Part 1: Performance rating procedure using
indoor test methods, involves testing for periods of one day for a standardized set of reference conditions. The
results, therefore, allow systems to be compared under identical solar, ambient and load conditions.
0.3 Black box correlation procedures
ISO 9459-2, Solar heating — Domestic water heating systems — Part 2: Outdoor test methods for system
performance characterization and yearly performance prediction of solar-only systems, is applicable to solar-
only systems and solar-preheat systems. The performance test for solar-only systems is a “black box”
procedure which produces a family of “input-output” characteristics for a system. The test results may be used
directly with daily mean values of local solar irradiation, ambient air temperature and cold water temperature
data to predict annual system performance.
0.4 Testing and computer simulation
ISO 9459-4, Solar heating — Domestic water heating systems — Part 4: System performance
characterization by means of component tests and computer simulation, a procedure for characterizing annual
system performance, uses measured component characteristics in a computer simulation program.
Procedures for characterizing the performance of system components other than collectors are also presented
in this part of ISO 9459. Procedures for characterizing the performance of collectors are given in other
International Standards.
ISO 9459-5, Solar heating — Domestic water heating systems — Part 5: System performance
characterization by means of whole-system tests and computer simulation, presents a procedure for dynamic
testing of complete systems to determine system parameters for use in the “Dynamic System Testing
Program”. This software has been validated on a range of systems; however, it is a proprietary product and
cannot be modified by the user. Implementation of the software requires training from a test facility
experienced with the application of the product. This model may be used with hourly values of local solar
irradiation, ambient air temperature and cold water temperature data to predict annual system performance.
The procedures defined in ISO 9459-2, ISO 9459-4 and ISO 9459-5 for predicting yearly performance allow
the output of a system to be determined for a range of climatic conditions.
The results of tests performed in accordance with ISO 9459-1 provide a rating for a standard day.
The results of tests performed in accordance with ISO 9459-2 permit performance predictions for a range of
system loads and operating conditions, but only for an evening draw-off.
0.5 Introduction to ISO 9459-4
ISO 9549-4 presents a procedure predicting the annual performance of a solar thermal system using a
numerical simulation programme. The parameters of the characterisation of the thermal behaviour of the key
components such as solar collector, store and controller are derived from physical tests of the components.
Because testing of the complete system as a whole is especially expensive and time consuming for system
families, this approach offers the opportunity to determine the annual performance of a family of systems with
limited effort.
NOTE A system family is characterised by a series of hot water systems that are identical with regard to their
construction and only differ in their collector and storage dimension. An identical construction is given if the set-up of the
system is similar (pipes, electrical pump, hydraulic connections, type but not mandatorily size of the heat exchanger), the
insulation concept is similar (material, thickness) and the collectors installed are from the same type.
Procedures exist for testing most solar thermal system components. Where they exist, they are referenced. In
case no standardised component test procedures are available appropriate procedures have to be used to
determine the thermal characteristics of the components.
The intention of this International Standard is to determine the thermal performance of the system. Therefore,
it is assumed that all key components (e.g., collectors, stores, heat exchangers, etc.) used in the system are
subjected to relevant durability tests (e.g., collector qualification tests, pressurization of the collector side of
the heat exchanger, etc.) before they are tested for thermal performance.
In order to ensure a proper operation of the entire system additional durability tests may be required of the
complete system to determine operation under extreme conditions such as freezing or overheating based on
corresponding standards.
The performance evaluation procedure defined in this International Standard has been designed to provide a
means of evaluating the annual task performance of heated water systems.
This International Standard sets out a method of evaluating the annual energy performance of heated water
systems using a combination of test results for component performance and a mathematical model to
determine an annual load cycle task performance. This International Standard defines a procedure for
evaluating the task performance of conventional electric and
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