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Building Engineering Services Association Guide to Good Practice for: Heat Pumps TR 30 July 2021 www.thebesa.com

ISBN 978-0-903783-58-3 First edition V1 2013 Second edition V2 2021 ©2021 BESA All rights reserved BESA Publications Old Mansion House Eamont Bridge Penrith CA10 2BX 0207 313 4900 [email protected]

ACKNOWLEDGEMENTS The BESA would like to acknowledge those members of the expert panel who contributed their time, experience and knowledge in the drafting of this guidance. Experts Panel Jonathan Coppock Graeme Fox Graham Hazell Neil Macdonald Will Pitt Bruce Young Notes Manufacturing techniques are continually subject to change and improvements and in respect of proprietary methods and devices this guide does not preclude their use if they can be demonstrated to the system designer to be equally satisfactory. Where there is divergence between the requirements of and the manufacturer’s recommendations for proprietary methods and devices, the latter shall take precedence. This document is based on knowledge available at the time of publication and is meant for general purposes, not for reliance on in relation to specific technical or legal issues, in which case you should always seek independent advice. No responsibility of any kind for any injury, death, loss, damage or delay however caused, resulting from the use of the advice and recommendations contained herein, is accepted by the authors or others involved in its publication (including the Building Engineering Services Association). The Building Engineering Services Association Guide to Good Practice for Supports and Fixings 3

FOREWORD In order to address the climate change emergency and the associated impacts, the UK Government has set a target of achieving net zero carbon emissions by 2050. Given that the built environment is responsible for around 40% of total carbon emissions, it is clear that radical change is needed in the sector in order to meet this target. High carbon fossil fuels used to heat homes and buildings will need to be replaced with low carbon alternatives. The de-carbonisation of the electricity grid is driving a shift towards electric heating technologies with heat pumps forecast to make up a significant part. The Committee on Climate Change has said that to meet the commitment to reach net- zero by 2050, 19 million heat pumps will need to be installed and that hybrid heat pumps should be widely used by 2035. According to the Heat Pump Association in their Road Map for delivering Net Zero, the industry will require an additional 40,000 competent engineers in order to meet the anticipated increase in demand. Heat pumps are not a new technology and they have been used in a variety of different applications for many years. This guide aims to provide an overview of the different applications including their benefits and limitations as well as providing outline design information for each of them. Independent of any manufacturer, it is not intended to supersede design data or instructions provided by suppliers, whose recommendations should always be followed. References to building standards and codes of practice have been updated in this latest version of the guide as well as data referenced from CIBSE or BSRIA guides. Carbon emission factors have been updated along with new and emerging technology using different refrigerant types and blends which bring new hazards and safety considerations. Since the first edition of this guide was published, there has been a significant increase in the use of heat pump technologies. This uptake has resulted in a broader range of choices for end users, specifiers and installers, and also a greater knowledge of their potential benefits and pitfalls. New regulations, assurance schemes, government incentives and market entrants have led to the development of a landscape where heat pump technologies are playing an increasing part and where there is a need for a recognised source of good practice to be made widely available to avoid some of the potential design pitfalls. The Guide is part of a suite of publications covering generic installation requirements for a range of renewable energy and sustainable systems including biomass, solar thermal hot water, combined heat and power (CHP), rainwater harvesting, heat metering, district heating, heat networks and heat interface units. It draws on the wide range of existing BESA publications covering good practice in building engineering systems which together support the effective integration of these systems into the built environment. Will Pitt Chair, BESA Technical Committee 4 The Building Engineering Services Association Guide to Good Practice for Heat Pumps

CONTENTS Acknowledgements 3 Foreword 4 Contents 5 Sections Section 1 Introduction 7 Section 2 General 9 Section 3 Specific Requirements 22 Section 4 Troubleshooting Guidance 37 for Heat Pump Systems Section 5 Example of MCS 022 Data for 41 Extraction Rates Bibliography 43 Figures Figure 1 Heat pump 11 Figure 2 Outside unit of split air source 13 heat pump Figure 3 Components of ground source 13 heat pump Figure 4 Heat pump testing to EN 14511 15 Figure 5 Installation of twin compressor heat 17 pumps in a large manor house (front covers removed) Figure 6 External siting of ground source single 17 compressor heat pump type (front cover removed) Figure 7 Shallow horiziontal ground loops 25 Figure 8 Single port manifold connecting the 26 heat pump to the ground array Figure 9 Typical borehole details 27 Figure 10 Preparation of boreholes 28 Figure 11 Twin probe borehole 29 Figure 12 Example hydronic circuit with heat 31 pump and boiler Figure 13 Examples of domestic hot water 33 provision a) Example of heat pump package with integral domestic hot water tank b)Example heat pump package with external domestic hot water cylinder The Building Engineering Services Association Guide to Good Practice for Heat Pumps 5

CONTENTS Tables Table 1 Carbon dioxide emissions 9 Table 2 Heat Sources 12 Table 3 Typical heat pump packages 13 Table 4 Standard rating conditions 14 air to air heat pumps - heating mode. Table 5 Standard rating conditions 14 water to air and brine to air heat pumps - heating mode. Table 6 Standard rating conditions 14 water to water and brine to water heat pumps - heating mode Table 7 Standard rating conditions 14 air to water and air to brine heat pumps -heating mode Table 8 SAP Heat pump seasonal efficiency 19 Table 9 Minimum recommended COP for warm 20 and hot water heat pumps in new and existing buildings Table 10 Minimum recommended COP for heat 20 pumps in new and existing non-domestic buildings Table 11 Minimum COP required by McS 20 Table 12 Specific extraction output for buried 26 heat exchangers Table 13 Specific heat extraction rate for 28 borehole heat exchangers 6 The Building Engineering Services Association Guide to Good Practice for Heat Pumps

SECTION 1 INTRODUCTION 1.1 Objective This guide has been produced to assist professional building services engineers to specify, design and install heat pump systems for heating and cooling in buildings. These systems are usually based on packaged heat pump equipment where all necessary components and controls for the refrigerant circuits are pre assembled and tested. They can also be delivered in components where the outdoor unit and indoor unit(s) have the refrigerant circuits formed and connected in the field. The emphasis is therefore on the successful installation and integration of these packages into conventional heating and cooling systems. 1.2 Standard of workmanship The standard of workmanship set by this publication is intended to be appropriate to most normal domestic and commercial installations and, relates to good practice in installation and energy use without unnecessary elaboration. BESA intends this to be a significant aid in producing installations that will, given correct operation and with proper maintenance, provide satisfactory service over many years. For large buildings and those with unusual or special requirements, the particular requirements should be agreed between customer and designer. 1.3 Quality assurance This publication can be used as one criterion that will assist customers, in performing the important role of defining the standard of installation they require. BESA anticipates that this publication will be complementary to quality assurance schemes and quality assessment schedules. Where forming the basis of an independent certification scheme, it represents good practice in standards of installation. 1.4 Scope This publication covers packaged heat pumps with electrically driven compressors usually found in domestic, residential and small commercial premises for space heating and hot water systems. The Guide does not consider: • heat pump systems used only for cooling (Refer to BESA publication RAC80) • large heat pump systems, purpose designed and constructed from discrete components • heat pump systems used for industrial processes • absorption heat pumps or gas engine heat pumps This publication relates to projects in the UK and the Republic of Ireland. It is not intended for overseas work however, some of its provisions will be appropriate or may form a basis for overseas work. This publication makes reference to the relevant CIBSE, BSRiA and MiS 3005 documents. The Building Engineering Services Association Guide to Good Practice for Heat Pumps 7

This publication makes use of terms “should”, “shall” and “must” when prescribing procedures: 1. The term “must” identifies a requirement by law at the time of publication. 2. The term “shall” prescribes a procedure which, it is intended to be complied with, in full and without deviation. 3. The term “should” prescribes a procedure which, it is intended to be complied with unless, after prior consideration, deviation is considered to be acceptable. 1.5 Publication review User feedback on the content or the requirements of the guidance will be welcomed to assist in the ongoing development of this document. [email protected] 8 The Building Engineering Services Association Guide to Good Practice for Heat Pumps