General FAQS

What is district heating?

Here in the UK, heating tends to be generated on-site, in individual buildings. The most common sources of heat are gas boilers, electric heaters and oil-powered boilers. However, in many parts of the world it is common to use local networks to transport heat to consumers through insulated pipes. This process is called “district heating”.

In these cases, the heat source is not contained inside each individual building but is generated locally at a combined heat and power (CHP) plant – reducing the losses normally associated with electricity or gas heating production. The heat is distributed to many consumers via a network of pipes, in a similar way to a domestic central heating system, but on a much larger, community-wide scale.

How is my home heated?

Heating and hot water is generated centrally and is distributed around the local area via a network of insulated pipes. This primary network links with the secondary network in your building which provides your heating and hot water.

The energy for your heating system comes from the combined heat and power plant (CHP) at an energy centre within your district heating scheme. The hot water from our network passes through the equipment in your home’s airing cupboard and is circulated through your home like a conventional central heating system.

The hot water in your home is fed by a heat exchanger, called a Heat Interface Unit (HIU). The hot water can be manually programmed to come on at certain times using a time clock-based programmer in your home.

Modern heat networks are fitted with in-property Heat Interface Units (HIUs) and heating controls, so that each consumer has as much control as they would with a more conventional system. An HIU contains a heat exchanger that transfers heat from the heat network to the pipes within an individual property. HIUs can look very similar to gas boilers. It can be difficult for domestic consumers to know that they’re on a heat network just by looking at the utility appliances within their home.

We regularly inspect your HIU and if we have been in your property to carry out repairs, we would have also completed the inspection. You can request an inspection by completing this form.

What are the benefits of district heating?

There are global, European and UK targets to reduce carbon emissions. One way of significantly reducing carbon emissions is to generate energy as close to the end users as possible. Using a district CHP plant allows electricity and heat to be generated and distributed locally.

As they are built on a far larger scale than typical domestic central heating systems, district heating schemes allow those participating to benefit from low-carbon technologies and economies of scale. More efficient generation of heat and fewer carbon dioxide emissions also help the environment.

Is the heat I receive enough to provide heat and hot water to my home?

Yes. Our heating network is a variable volume, low-temperature hot-water distribution system. It operates with a constant temperature differential, nominally with a flow temperature of 95°C (+15% under certain conditions) and a return temperature of 55°C.

What is a heat interface unit?

The heat interface unit (HIU) is a box that looks like a boiler. It transfers the heat from the district heating network into your home, it makes heat available instantly, whenever it’s required for hot water or central heating. Modern heat networks are fitted with in-property Heat Interface Units (HIUs) and heating controls, so that each consumer has as much control as they would with a more conventional system. An HIU contains a heat exchanger that transfers heat from the heat network to the pipes within an individual property. For more information on Heat Networks please visit: https://www.heattrust.org/about-heat-networks

HIU’s need to are inspected every two yearsand our service timelines are aligned to those specified by the Heat Trust.

If you would like us to inspect your HIU, please complete the form here.

How are tariffs calculated?

As each heat network involves significant upfront investment in the infrastructure of buried networks and central energy plant, long-term energy supply contracts are needed to allow that investment to be recovered over time, typically for between 25 and 40 years. Accurately projecting costs (especially fuel) over that time is very difficult as prices constantly change (similar to petrol prices on a forecourt station) and can be affected by global events or economic shocks.

To keep prices affordable and competitive for the customer across the life of network, operators use a controlled process agreed at the point of construction, for the management of tariffs. This takes a baseline tariff at the time of first occupation and provides for the tariff to be changed after agreed time periods in accordance with a prescribed formula, based on published indexes, or 12-month energy price forecasts.

Tariffs comprise of fixed charges (to cover the cost of operation, maintenance and life-cycle plant replacement) as well as variable charges (to cover the cost of energy/fuel consumed). Each component of the tariff uses different indexation mechanisms to determine what changes are justified at any one periodic review.

The biggest impact on tariffs this year has been the price of wholesale gas, which has risen significantly. This has affected prices on a whole range of energy systems, including heat networks, and domestic gas boilers, across the UK.

Why am I not protected by the OFGEM price cap?

Heat networks operators can only procure their gas supply through commercial markets, unlike large residential energy suppliers who procure through the wholesale market, which is typically less expensive. As such heat networks are classified as commercial supplies, and therefore the OFGEM price cap does not apply.

The government is proposing legislation that would provide OFGEM powers to improve consumer protection for residential customers of heat networks, including powers to regulate tariffs. This is a decision that we support, and we are working closely with the government and industry bodies to bring this forward.

Importantly, our tariff is set for 12 months and reviewed annually in April.

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