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