ISO INTERNATIONAL STANDARD 21978 Second edition 2023-12 Air to water heat pumps Testing and rating at part load conditions and calculation of seasonal coefficient of performance for space heating Chauffe-eau a pompe a chaleur - Essais et détermination des caractéristiques a charge partielle et calcul de performance saisonniere Reference number ISO 21978:2023(E) rso @IS02023 IS0 21978:2023(E) COPYRIGHT PROTECTED DOCUMENT @ISO2023 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on or ISo's member body in the country of the requester. ISO copyright office CP 401 · Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +41 22 749 01 11 Email: copyright@iso.org Website: www.iso.org Published in Switzerland i @ IS0 2023 - All rights reserved IS0 21978:2023(E) Contents Page Foreword ..V Introduction. ..vi 1 Scope. 2 Normative references 3 Terms and definitions. 4 Symbols. ..8 5 Installation requirements .9 5.1 Test apparatus and uncertainties of measurement ..9 5.2 Test room for the airside .10 5.3 Installation and connection of the heat pump 10 5.4 Installation of heat pumps consisting of several parts. ..11 5.5 Environment conditions for indoor unit installation and electrical power supply requirements. 11 6 Setting and part load test conditions ..11 6.1 General 11 6.2 Setting for capacity ratio 11 6.3 Setting the external static pressure difference for ducted units ..11 6.4 Setting of units with integral pumps. ..12 6.5 Part load test conditions. ..12 ..15 7 Space heating test 7.1 Heating capacity test. ..15 7.2 Heating capacity correction .. 16 7.2.1 General .16 7.2.2 Capacity correction due to indoor liquid pump .. 16 7.2.3 Effective power input. 17 7.3 Test procedure. 7.3.1 General . 19 7.3.2 Permissible deviations. 19 7.3.3 Preconditioning period .20 7.3.4 Equilibrium period .21 7.3.5 Data collection period. 21 7.4 Heating capacity calculation. 21 7.4.1 Steady state capacity test 21 7.4.2 Transient capacity test. 21 7.5 Effective power input calculation 21 7.5.1 Steady state test. 21 7.5.2 Transient capacity test. 21 7.6 Determination of degradation coefficient C. 21 7.7 Test methods for electric power input during thermostat-off mode, standby mode, crankcaseheatermodeandoffmode. .22 7.7.1 Uncertainties of measurement .22 7.7.2 Measurement of electric power input during thermostat-off mode 22 7.7.3 Measurement of electric power input during standby mode .23 7.7.4 Measurement of electric power input during crankcase heater mode. 23 7.7.5 Measurement of electric power input during off mode .23 8 Calculation methods for seasonal coefficient of performance (Scop) .23 8.1 General formula for calculation of Scop.... 23 8.2 Calculation of the reference annual heating demand, Q 24 8.3 Calculation of the annual energy consumption, QHe- 24 8.4 24 8.5 Calculation procedure for determination of Cpb values at part load conditions A to G...26 IS0 2023 - All rights reserved iii