ISO 13256-2:2021

INTERNATIONAL ISO
STANDARD 13256-2
Second edition
2021-05
Water-source heat pumps — Testing
and rating for performance —
Part 2:
Water-to-water and brine-to-water
heat pumps
Pompes à chaleur à eau — Essais et détermination des
caractéristiques de performance —
Partie 2: Pompes à chaleur eau-eau et eau glycolée-eau
Reference number
©
ISO 2021
© ISO 2021
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ii © ISO 2021 – All rights reserved

Contents Page
Foreword .v
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 4
5 Rating and test conditions . 5
5.1 Rating conditions for the determination of net capacities . 5
5.1.1 Ratings . 5
5.1.2 Load side liquid pump adjustment . 5
5.1.3 Source side liquid pump adjustment . 6
5.1.4 Liquid flow rates . 7
5.1.5 Installation and connection of the unit . 7
5.1.6 Test liquids . 8
5.2 Rating test conditions for cooling and heating capacities . 8
6 Performance Requirements. 9
6.1 General . 9
6.2 Maximum operating conditions test .10
6.2.1 Test conditions.10
6.2.2 Test procedures.10
6.2.3 Test requirements .10
6.3 Minimum operating conditions test .12
6.3.1 Test conditions.12
6.3.2 Test procedures.12
6.3.3 Test requirements .12
6.4 Enclosure sweat and condensate test .13
6.4.1 General.13
6.4.2 Test conditions.13
6.4.3 Test procedures.14
6.4.4 Test requirements .14
7 Test methods .14
7.1 General .14
7.2 General test requirements .14
7.3 Equipment installation .14
7.4 Cooling and heating capacity tests procedure .15
7.4.1 Reconditioning period .15
7.4.2 Data collection period .15
7.4.3 Net cooling capacity .15
7.4.4 Net heating capacity .16
7.5 Uncertainties of measurement .16
7.6 Data to be recorded .16
7.7 Uncertainties of measurements and permissible deviations for steady-state
cooling and heating capacity tests .17
7.8 Test results.18
8 Marking provisions .18
8.1 Nameplate requirements .18
8.2 Nameplate information .18
8.3 Designation of standard rating capacities .19
8.4 Refrigerant Designation .19
9 Publication of ratings .19
9.1 Published ratings .19
9.2 Additional ratings .19
Annex A (informative) Refrigerant enthalpy test method.20
Annex B (normative) Liquid enthalpy test method .22
Annex C (informative) Additional ratings based upon previous standard version
ISO 13256-2:1998.24
Bibliography .26
iv © ISO 2021 – All rights reserved

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
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
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URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 86, Refrigeration and air-conditioning,
Subcommittee SC 6, Testing and rating of air-conditioners and heat pumps.
This second edition cancels and replaces the first edition (ISO 13256-2:1998), which has been
technically revised.
The main changes compared to the previous edition are as follows:
— Significant updates to the formatting, symbols, and terms and definitions, have been included to
more closely align with other pertinent ISO standards and the latest ISO requirements.
— The original water loop heat pump (WLHP), ground water heat pump (GWHP) and ground loop
heat pump (GLHP) application rating designations, specifying entering liquid source rating test
conditions, have been replaced with High, Medium, and Low source temperature range conditions to
represent a wider operating map at both standard and partially loaded application rating conditions.
It is now possible, when all three (High, Medium and Low) temperature ranges are specified by the
manufacturer for energy modelling progra
...