HEAT NETWORKS
www.heatingandventilating.net
Modernising heat networks: why HIU upgrades are key
Many heat network systems installed over a decade ago are now underperforming due to ageing infrastructure and ineffi ciencies not anticipated at the time of design. Charlie Mowbray, senior product manager, Ideal Heating – Commercial explains why heat interface units (HIUs) hold the key to effi ciency upgrades
T
o support the upgrade of these underperforming systems, the UK government launched the Heat Network
Effi ciency Scheme (HNES). With £32 million available through 2025, HNES provides grant funding to public, private, and third-sector organisations for refurbishments. While most attention tends to focus on modernising energy centres, the performance of HIUs must also be scrutinised, as they are crucial to how heat is delivered and used at the point of use.
Legacy HIUs and the impact on effi ciency
In many cases, poor network performance isn’t solely down to outdated boilers or plant equipment. A signifi cant portion of the ineffi ciency arises from older HIUs that were installed before any formal test regime was in place. Without performance standards like the BESA HIU Test Regime, many of these early units were installed without clear expectations around their operational eff ectiveness.
These legacy HIUs often struggle to manage
temperature control, off er limited adjustability, and are diffi cult to maintain. In addition, some manufacturers are no longer in business, meaning support and spares are either unavailable or not cost-eff ective. The consequence is high return temperatures, which reduce the effi ciency of the entire system. Even when the core plant is upgraded, these return temperatures can undermine overall performance. One increasingly popular approach is the
replacement of HIUs on a distressed basis— replacing individual units as they fail, rather than undertaking a full-scale retrofi t. This can be an effi cient use of resources if new HIUs are compatible with the network’s design parameters, including fl ow and return temperatures and diff erential pressure.
Choosing modern HIUs for retrofi t applications
Modern HIUs are engineered to control return temperatures more eff ectively, which has a direct impact on system effi ciency. They also provide better user control, improved hot water responsiveness, and are often designed for easier installation and ongoing maintenance. While
20 December 2025
Above: Charlie Mowbray, senior product manager, Ideal Heating
performing HIUs can cause excessive energy use and service callouts. If replacing these units leads to measurable effi ciency improvements, the return on investment can often be realised in as little as 18 to 24 months. Once this initial payback period is passed,
laboratory testing can highlight small performance diff erences between units, in real-world applications, ease of installation, commissioning and serviceability can be just as critical as technical specifi cations. Poor commissioning or inaccessible components can negate the benefi ts of even the most technically capable equipment. Therefore, decisions around HIU selection should consider not only energy performance but also operational usability and long-term support from the manufacturer. Ideal Heating Commercial’s POD HIUs off er a layout that prioritises access and usability, simplifying the installation and maintenance process.
The economics of HIU replacement
The upfront cost of replacing HIUs—particularly across large estates—can be signifi cant. However, many network operators are fi nding that the long-term benefi ts justify the investment. Poor-
the savings continue throughout the lifespan of the equipment, which typically ranges from 15 to 25 years. With funding support from HNES, organisations may be able to reduce the capital burden and justify upgrades based on data- driven projections. Housing associations, Energy service companies (ESCOs), and social landlords, in particular, are well positioned to benefi t— especially where poor effi ciency directly impacts operating costs and tenant comfort.
Futureproofi ng through strategic investment
Refurbishing heat networks isn’t just about fi xing short-term problems. It’s about futureproofi ng infrastructure for a low-carbon future. While new heat networks will undoubtedly play a role in decarbonisation, there is a vast stock of existing systems that must be brought up to modern standards if the UK is to meet its emissions targets. HIUs are fundamental to how a heat network
performs. By investing in modern, test-certifi ed, and serviceable units, organisations can unlock substantial performance gains.
DOWNLOAD THE HVR APP NOW
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40
