HEAT & ENERGY BRIEFING
Make sure it does what it says on the label
I
The introduction of the Heat Network Technical Assurance Scheme (HNTAS) will bring a fundamental change to the way heat networks are designed, installed and verified. For everyone involved in specifying and installing Heat Interface Units (HIUs), one detail is set to become increasingly important: the BESA test label, as Steve McConnell, director, Manufacturers of Equipment for Heat Networks Association (MEHNA), explains
t may only be a sticker, but this label provides the evidence that the HIU installed on site has been independently tested for product performance in line with the requirements of Version 3.1 the Building Engineering Services Association (BESA) standard. For specifiers, architects, contractors and developers, that makes checking for the label a simple but important part of procurement and installation.
And for manufacturers, the message from MEHNA is equally straightforward: if you claim an HIU has been tested to the BESA HIU Test Regime, make sure the unit carries the appropriate BESA identification label and QR code.
From best practice to assurance
Heat networks are entering a new era of technical assurance. HNTAS, introduced under powers in the Energy Act 2023, is intended to provide independent assurance that heat networks are designed, installed and operated to defined technical requirements. Government currently plans for HNTAS to launch in 2027, following further development and finalisation of the scheme.
TS1 – the Heat Network Technical Standard – is a key part of that framework. It sets out technical requirements across the heat network, including the consumer connection, where the HIU normally sits. HIUs are particularly important because they
are the interface between the communal or district network and the individual dwelling. Their performance affects hot water delivery, space heating, return temperatures, network efficiency and ultimately the experience of the consumer. That is why the BESA HIU Test Regime has become such an important part of the technical assurance process. Version 3.1 of the BESA standard was published in 2026 and introduces revised performance thresholds and additional pass/fail criteria, including for indirect space heating average temperature and mix-down temperature stability. It supersedes the previous version of the standard.
Why the label matters
BESA’s product identification requirements state that HIUs that have passed the test regime and are registered should carry a BESA label, either attached to the HIU or incorporated into the product data label. The label identifies the manufacturer, model or serial number, test date and BESA registration code. Crucially, it also incorporates a QR code that links directly to the relevant individual test report on the BESA website.
That creates a straightforward chain of evidence, and this traceability is going to be increasingly important as HNTAS moves from preparation into implementation. An assessor looking at a completed heat network needs to be able to establish that the equipment installed is consistent with the equipment specified and tested. The label provides a quick and practical way of doing that. MEHNA’s own HIU installation, commissioning and maintenance guidance makes the point explicitly: HIUs tested to Version 3.0 or later can be identified through the appliance data label or an external casing label, with the QR code linking the installed HIU to its published test results. If there is no label or link, the guidance says the HIU should not be installed until its status has been confirmed with the network designer and manufacturer. So, this should not be regarded as an administrative detail to be dealt with after the HIU has arrived on site. The label is part of the evidence.
What does this mean for specifiers?
For architects, consultants and specifiers, the starting point is simple: specify HIUs that have appropriate, published BESA test results and make the identification and traceability requirements clear within procurement documentation. A BESA-registered product is not automatically the right HIU for every heat network. The test results still need to be considered alongside the design conditions of the particular scheme. BESA itself stresses that procurement decisions should take account of the network design and other relevant product attributes. However, where a BESA-tested HIU is specified, the specification should not stop at the words ‘BESA tested’. The requirement should extend to the individual units supplied carrying the appropriate BESA identification label and QR code, giving the contractor, commissioning team, operator and eventual HNTAS assessor a means of verifying what has actually been installed. It also reduces the risk of a situation where paperwork says one thing, but the physical product on site cannot be positively linked to the test evidence.
The same principle applies to contractors. When HIUs arrive on site, the BESA label should be one of the things checked alongside the model, serial number and other product information. If the label is present, scanning the QR code
provides a direct route to the relevant test report. If it is missing, the issue should be raised before installation rather than discovered when the project is approaching sign-off. This is particularly important because BESA’s labelling requirements are designed to identify
8 BUILDING SERVICES & ENVIRONMENTAL ENGINEER NOVEMBER 2026
the specific HIU type and model that has been tested and registered. Changes to components or software can affect whether the original test results remain valid, with BESA’s Engineering Change Process providing the mechanism for determining this. In other words, a label is not simply evidence that a manufacturer has tested an HIU at some point in the past. It is intended to identify the product being installed and connect it to the appropriate test evidence.
Manufacturers need to act now
Some manufacturers have already embraced the latest BESA 3.1 testing and identification process, with Version 3.1 results now appearing on the BESA register. But not every manufacturer has yet made that transition. There is understandable pressure on manufacturers to manage the cost and logistics of retesting products against a revised standard. However, delaying the process creates uncertainty further down the supply chain. Specifiers need confidence that products being proposed for new schemes will meet the requirements of the developing HNTAS framework. Contractors need confidence that the products delivered to site can be demonstrated to be compliant. And assessors need clear evidence when they come to verify the completed system. The industry cannot achieve that if testing is left until the last minute.
And finally…
My advice to specifiers, architects and contractors is therefore to make the label part of the normal procurement and site inspection process. Don’t simply ask whether an HIU has been tested. Ask whether the HIU being supplied carries the BESA label and whether its QR code takes you to the relevant test results. For manufacturers, the message is equally clear: if you have not yet completed the BESA 3.1 testing process, now is the time to start. The test house currently undertaking the relevant BESA HIU testing is a member of MEHNA. HNTAS may still be working towards its formal implementation, but the direction of travel is clear. The industry has an opportunity to make good practice routine before it becomes a requirement. And when the assessor arrives, a small label on the front of the HIU could provide one of the clearest pieces of evidence that the right product has been tested, registered and installed. For further information and to read the guide, visit MEHNA-Installation-Commissioning-and- Maintenance-of-Heat-Interface-Units-FINAL. pdf [
https://www.mehna.org.uk/
media/7bcb8ad74dfaa5bcd396401f1a9f0d09/ MEHNA-Installation-Commissioning-and- Maintenance-of-Heat-Interface-Units-FINAL.pdf]
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