09 February 2026
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The Manufacturers of Equipment for Heat Networks Association (MEHNA) has launched a new industry guidance document to support installers, commissioners and service engineers working with Heat Interface Units (HIUs) under the UK’s new Heat Network Technical Assurance Scheme (HNTAS).
‘Installation, Commissioning and Maintenance of Heat Interface Units for the Heat Network Technical Assurance Scheme’ provides practical guidance for professionals working on communal and district heat networks. It has been developed to reflect the regulatory requirements introduced under the Energy Act 2023, alongside the Heat Network Technical Standard (TS1) and the forthcoming BS 8635 regulation.
With heat networks expected to supply up to 20% of UK heat demand by 2050, the performance of HIUs has become an important factor in system efficiency, consumer satisfaction and carbon reduction. Under HNTAS, the ‘Consumer Connection’, typically an HIU, is now a regulated element of a heat network, with mandatory verification of installation and commissioning. MEHNA’s new guide is designed to help the industry meet these requirements consistently and demonstrably.
The document covers the full lifecycle of an HIU installation, including:
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How heat networks function and where the HIU sits within the system
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Best practice installation for direct and indirect HIUs
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Commissioning procedures and acceptance testing aligned to HNTAS
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Ongoing maintenance and servicing requirements
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Fault-finding using heat meters and component testing
It also aligns with key national standards, including TS1, the BESA HIU Test Regime, BS 7593, BS EN 12828, and forthcoming BS 8635 Part 2.
The guide has been jointly authored by technical specialists from across the sector and peer reviewed by a wide range of industry stakeholders, including manufacturers, network operators, consultants and policy bodies. It is intended as a reference document for trained installers and service engineers, as well as a supporting resource for designers, heat network operators and independent HNTAS assessors.
Steve McConnell, Director of MEHNA, said: “HIUs are the critical interface between a heat network and the consumer. Under HNTAS, we now have a legal framework that requires those interfaces to be installed and commissioned exactly as designed, and to perform as intended. This guide translates national standards into clear, practical procedures that can be applied on site.
“The guide has been lauded by the Department of Energy Security & Net Zero (DESNZ) in supporting best practice for a growing sector. It represents a major step forward in raising quality and consistency across the heat network sector.”
The guide forms part of MEHNA’s wider programme to support professional standards, training and technical assurance across the heat network supply chain.
For further information and to read the guide, visit: MEHNA-Installation-Commissioning-and-Maintenance-of-Heat-Interface-Units-FINAL.pdf
