## What is a heat exchanger?

A heat exchanger is a system used to transfer heat between a source and a working fluid. Within district heating systems, a heat exchanger is typically used in a device called a heat interface unit (HIU), which is installed in each building connected to the [**district heating network**](/what-is-district-heating "What is district heating?").

On the exterior HIUs look very similar to individual boilers, however play a very different role within district heating.

**[Learn more about HIUs. ](/what-is-a-hiu "What is a heat interface unit?")**



 

 

 



 

 

**How can Veolia help you?**

**Veolia District Heating Services are a proud member and practitioner of the Heat Trust standards. Get in touch for advice.**

[Make an Enquiry](https://www.veolia.co.uk/energy-services-new-customer-enquiry)

 



 

 

 

 

 

 





 

 

 

 





## What does a heat exchanger do within heat interface units?

The primary function of the heat exchanger in an HIU is to transfer heat from the hot water in the district heating network to the cold water in the building's heating system. This is done by allowing the hot water from the district heating network to flow through one side of the heat exchanger, while the cold water from the building's heating system flows through the other side. As the two streams of water flow past each other, heat is transferred from the hot water to the cold water, warming the cold water for use in the building's heating system.

Heat exchangers in HIUs are typically designed to be highly efficient, with minimal heat loss. This helps to ensure that the building's heating system operates efficiently and that energy is not wasted.

In addition to transferring heat from the district heating network to the building's heating system, HIUs may also include other components, such as pumps, flow meters, and control systems, to help regulate the flow of water and ensure that the building's heating system operates correctly.



 

 

 

 

 

 





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###       [Commercial Heat Exchanger Cleaning](https://www.veolia.co.uk/services/heat-exchanger-cleaning) 

 

 

 



 

 [   ![two engineers working on a heat pump](/sites/g/files/dvc1681/files/styles/media/public/image/2021/07/image%20%288%29.png.webp?itok=9YzV7LCc)   ](https://www.veolia.co.uk/services/heat-pumps)[Veolia Heat Pumps](https://www.veolia.co.uk/services/heat-pumps)

 

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 [   ![District Heating Case Study CGI](/sites/g/files/dvc1681/files/styles/media/public/image/2023/02/Copy%20of%2003_DISTRICT%20HEATING_04_HD-3840x2160.jpg.webp?h=e2f56056&itok=cqEfwan8)   ](https://www.veolia.co.uk/what-is-a-hiu)[What is a HIU?](https://www.veolia.co.uk/what-is-a-hiu)

 

###       [What is a HIU?](https://www.veolia.co.uk/what-is-a-hiu) 

 

 

 



 

 

 





## **Get in Touch**

**If district heating appears to be a viable route for you then we strongly urge that you seek out expert knowledge and advice to ensure your network/scheme is built and managed to provide the highest levels of efficiency.**

[Enquiries](https://www.veolia.co.uk/energy-services-new-customer-enquiry)