EDGE Heat Interface Units

A heat network, also known as district or communal heating, is a system that supplies LTHW to multiple buildings or dwellings from a central source (plant room). Instead of each home or business having its own boiler, heat is generated in one location (often using renewable or low-carbon energy) and delivered through insulated pipes within the heat network. This setup improves energy efficiency, lowers carbon emissions and makes it easier to use sustainable technologies.​

As of 2023, around 900,000 homes across the UK were connected to heat networks. That’s roughly 3% of all homes – and the number is steadily rising as part of the national effort to cut emissions and improve energy use.

Heat networks can use a mix of energy sources, including combined heat and power (CHP), waste heat from industry or data centres, energy-from-waste plants, biomass, and renewable options like heat pumps, geothermal, and solar thermal. Electric boilers may also be used, especially to support peak demand. The choice depends on local resources, carbon goals, and system design.

A HIU is a compact unit installed in individual dwellings or buildings that are part of a wider heat network. Instead of needing a boiler or gas supply in each home, the HIU acts as the connection point, drawing heat from the heat network and delivering it where it’s needed inside the property.

Here’s what a HIU does in simple terms –

• Transfers heat from the network’s central supply into your home.
• Provides space heating (radiators or underfloor) and often instantaneous domestic hot water.
• Works a bit like a boiler, except it doesn’t generate heat, it just distributes it efficiently.
• It gives each dwelling independent control over heating and hot water, even though they share the main heat source.
• Enables metering and billing per household, so users only pay for what they use.
• Removes the need for gas connections and individual boilers, lowering maintenance and improving safety.

Essco EDGE heat interface units are electronically controlled and supply both tertiary space heating and domestic hot water. Both circuits are hydraulically separated from the secondary heat network by twin SWEP plate heat exchangers (PHEs). Units feature first-class components, Including the market-leading flow control valve from ESBE and electronic temperature control technology.

Designing an effective heat network starts with a focus on energy efficiency and long-term reliability. Good practices include keeping pipework routes as short and insulated as possible to minimise heat loss, sizing the system accurately to meet demand without oversizing and planning for future expansion. Using low-carbon heat sources, integrating smart controls and ensuring each property has its own Heat Interface Unit (HIU) for independent control and metering are also key. Early stakeholder engagement, especially with developers, residents and local authorities, helps ensure the network is well integrated and user focused from day one.

For more information, refer to CP1 Heat Networks: Code of Practice for the UK (2020).

The installation time for a heat interface unit (HIU) depends on several factors, but here’s a general breakdown:

New build (pre-plumbed, first fix complete):

2 to 4 hours per unit

If the pipework and risers are already in place, the HIU can be mounted, connected, tested, and commissioned relatively quickly.

Retrofit in existing buildings:

4 to 8+ hours per unit

Older properties may need extra time for adapting pipework, managing access, or replacing legacy systems.

Complex installs (e.g. with metering, BMS integration, or multiple zones):

Up to a full day per unit

This includes flushing, commissioning, and any additional controls setup.

As HIUs are an inherently low maintenance space heating system, the recommendation from BSRIA BG 62/2015 is that a maintenance check every 3 years should be sufficient. Essco Group recommend that strainers however are checked at least once annually, depending on the water quality of the installation. Any build-up of debris can cause flow restriction and when left unchecked, damage to components within the HIU.

BSRIA inspection and maintenance procedure guidance recommends the following checks are carried out:

• No leaks associated with HIU or secondary distribution
• Primary isolation valves are operable
• Internal strainers are clear
• Supply differential above required minimum
• Thermal insulation is intact
• Control valves respond to demand signals for heating and hot water
• Supply temperatures to heating and hot water are as when the unit was commissioned
• Check mains pressure storage water heater safety valve (where fitted)
• Heat meter registers demand (or replace and commission new heat meter if scheduled)
• Consumer is satisfied with heating and hot water performance

Energy use is metered, but instead of tracking gas like a traditional boiler, it measures the actual heat delivered to the dwelling in kilowatt-hours (kWh). Each home has its own heat meter, so residents are only billed for the heating and hot water they use, offering clear, accurate and fair energy monitoring.

What are the payment options?
Payment systems can vary depending on the setup, but common options include prepayment (pay-as-you-go) systems, monthly billing or direct debit based on metered usage. Many providers offer online portals or mobile apps for easy top-ups and account management. Some systems also allow residents to view real-time usage, helping with budgeting and energy awareness.

Essco EDGE HIUs are billing neutral, ready for connection to any standard credit or PAYG system, so no tie-ins. We provide open access to meter readings via standard M-Bus set-up or remotely via third party.

District and communal heating can be cheaper and greener long term, but this depends on how it’s designed, managed and maintained.

A well managed scheme should prioritise energy efficiency, fair billing and ongoing optimisation.

Ultimately, the ability to change provider will future proof building operators against market changes and allow them to act in the best interests of residents. Essco EDGE units are open access, offering the flexibility to change billing provider and can integrate easily with existing communication networks where required.

Currently, heat networks in the UK are not regulated in the same way as gas or electricity, but that’s changing. Ofgem has been appointed as the future regulator, with new rules expected to come into force to ensure fair pricing, reliable service, and consumer protection. These upcoming regulations aim to bring greater transparency, improve standards, and give users similar rights to those they have with other energy suppliers.

In the meantime, Heat Trust acts as a voluntary protection scheme for heat network customers in Great Britain.

Yes. New buildings can be designed to connect easily to a heat network, while existing buildings can also be connected, though they may need some upgrades to their heating systems or insulation to ensure efficiency. Retrofitting is a common and proven approach.

5th generation district heating and cooling is a smart, low-temperature energy network that moves heat around at roughly the same temperature as the ground or air, letting buildings take or return heat as needed. Instead of one big boiler or chiller, each building uses its own small heat pump to raise or lower the temperature, making it more energy-efficient, flexible, and ready to work with renewables or waste heat from places like data centres.