HIUs & DISTRICT HEATING
Look after your HIUs, and they’ll look after you
The number of heat networks in the UK continues to grow rapidly as government backing for the technology increases in momentum. By September last year, over £1bn worth of heat network projects were travelling along the grant-funding pipeline, with almost a third of these already under construction. Jarrad Bedford, head of sales – operations & maintenance (O&M) at Insite Energy elaborates
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he sector’s rapid growth means more and more people every day are dealing with this complex communal technology for the first
time. For property managers and residents alike, it can be a lot to fathom. The efficiency of the entire network depends as much on a resident’s own energy behaviour as it does on their neighbours’. And while building managers need to maintain their share of the building, as a result of the communal nature, each household has a responsibility to manage its own system effectively to avoid driving up costs for everyone.
Critical component
The appliance that sits at the connecting point between residents’ individual properties and the wider network is their heat interface unit (HIU). As well as ensuring dependable heating and hot water supply for their home, their HIU gives them control over their energy use through room thermostats and hot water programmers. As such, an HIU looks and acts rather like a
traditional, individual gas boiler, to the point that some residents may not even be aware they’re connected to a heat network at all. Conversely, they may see their HIU as part of a larger communal system whose responsibility sits squarely with their building’s management, even though in many cases it may in fact be the residents’ job to maintain their own HIU. Either way, this is problematic because HIUs play
a vital role in the optimum functioning of the entire heat network, and a problem with one appliance can have expensive and far-reaching consequences. It’s critical they’re properly fitted, used and maintained.
When HIUs go wrong
A recent experience at one of our clients’ developments is a case in point. While the heat
30 April 2024
network at the 130-unit new build in central Cambridge initially appeared to be functioning well, a deeper dive into the performance data revealed an anomaly. The flow and return temperatures were at the expected levels, but the heat loss appeared to be slightly higher than anticipated. The problem was pinpointed to two flats that were bypassing on the heat network. The fault in both cases turned out to be
incorrectly positioned components within the HIUs, preventing valves from closing fully. It was a simple fix that had a surprisingly big impact on the heat network’s overall efficiency, given only two out of 130 HIUs were affected; return temperatures dropped around 7˚C and heat loss decreased from 4.1 to 2.9 kilowatt hour (kWh) per property per day,
Jarrad Bedford, head of sales – operations & maintenance (O&M) at Insite Energy.
saving about £6,000/annum in energy, or £46 per household.
The merit of monitoring
This story also highlights why it’s essential to monitor your heat network’s performance at a granular level, including via smart meters in every HIU. As well as providing minute-by-minute data showing flow rate and flow and return temperatures so you can quickly spot if things are going wrong, using smart meters to track efficiency can help to demonstrate HIU commissioning has been completed successfully. This is important for both engineers and property managers. Furthermore, if energy consumption data
captured by smart meters is made easily available to residents via a web-app like KURVE, this is proven to reduce energy use by around a quarter. KURVE displays a customer’s consumption over the day, week, month and year, giving them access to their data whenever they want. This also ensures compliance with increasingly stringent customer service and transparency obligations.
Regular maintenance
Because of the importance of HIUs to the efficiency of heat networks, impacting not only short-term energy-consumption levels but also the life expectancy of all equipment in the longer term, it’s vital they’re serviced regularly, and preferably around a similar time. That means including them in wider planned preventative maintenance (PPM) regimes; ensuring HIUs connected to one network are serviced together, or, if it’s residents’ responsibility, supporting them through regular servicing reminders or even a packaged service offering. Bear in mind, however, that some education may initially be needed about what an HIU is and why it’s so important to look after it properly.
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