UK Application of Heat Pumps V Heat Interface Units

min read time
2024-04-23 14:36:02

In the United Kingdom (UK), heat pumps and heat interface units (HIUs) are two common technologies used for heating residential and commercial buildings. Both systems offer unique advantages and considerations, and their application depends on factors such as building size, energy efficiency goals, and available infrastructure. 





Today in the next part of our weekly industry insight series Tony Croke, Product Manager for Indoor Climate Solutions in Wavin UK & Ireland, compares the UK application of heat pumps and HIUs, highlighting their respective features, benefits, and challenges.

Heat Pumps:


Heat pumps extract heat from the ambient environment (air, water, or ground) and transfer it to the building for heating purposes.

They are available in different types, including air source heat pumps (ASHPs), ground source heat pumps (GSHPs), and water source heat pumps (WSHPs). For the UK Air source heat pumps as a monobloc configuration is most common as it only requires water connections and not FGAS connections.

Heat pumps can also provide cooling during warmer months by reversing the refrigeration cycle although the effectiveness of this feature is limited due to dew point control issues.

Heat Pump Diagra

Source: Samsung Business UK


Energy Efficiency: Heat pumps can achieve high levels of energy efficiency, typically providing more (+3x ) heat output than the electrical energy consumed.

Renewable Energy Source: Heat pumps utilize ambient heat from the environment, making them a renewable and sustainable heating solution especially when coupled with a renewable electricity source.

Low Carbon Emissions: Heat pumps produce fewer carbon emissions compared to traditional fossil fuel-based heating systems, contributing to environmental sustainability.

Versatility: Heat pumps can provide heating, cooling, and hot water, offering a versatile solution for year-round comfort.



Upfront Cost: Heat pumps generally have higher upfront costs compared to conventional heating systems, including installation and equipment expenses.

System Design and Sizing: Proper system design and sizing are critical for optimizing heat pump performance and efficiency, requiring careful consideration of factors such as building insulation, heat loss, and climate conditions. The hot water / heating design temperatures of the system will be much lower than HIU’s or gas boilers requiring stored hot water in a cylinder and much larger heat emitters to maintain comfort levels.

Space Requirements: Ground source heat pumps require sufficient space for installation of ground loops or boreholes, which may be limited in urban areas or smaller properties. Air source heat pumps require an external wall location for the external heat exchange unit and a hot water cylinder and buffer vessel inside the dwelling.

Noise Levels: Air source heat pumps can generate noise during operation, which may be a consideration in noise-sensitive environments.

Heat Interface Units (HIUs):


HIUs are devices used in district heating systems to interface between the central heat source building boiler or Energy Centre heat network and individual buildings or units.

They regulate the flow and temperature of heat delivered to each building or unit, providing instant space heating and hot water as needed.

HIUs typically consist of components such as heat exchangers, pumps, controls, and sensors.


Heat Pump Diagram 2



Centralized Heating System: HIUs enable the use of centralized heating systems, such as district heating networks, which can offer efficiency benefits and reduce carbon emissions compared to individual heating systems.

Flexibility: HIUs can accommodate various heat sources, including gas boilers, biomass boilers, or heat networks, providing flexibility in system design and integration.

Space-saving: HIUs are compact and can be installed within individual buildings or units, minimizing space requirements and allowing for centralized control and monitoring.

Efficiency Optimization: HIUs can incorporate features such as modulating controls, heat metering, and remote monitoring to optimize system efficiency and performance.



Dependency on Heat Network: HIUs rely on the availability and reliability of the central heat network, and any disruptions or maintenance issues with the network can affect heating and hot water supply to individual buildings or units.

Installation and Commissioning: Proper installation and commissioning of HIUs are essential for ensuring optimal performance and efficiency, requiring coordination with building services and integration with the central heating system.

Maintenance and Servicing: HIUs require regular maintenance and servicing to ensure proper operation and efficiency, including cleaning, inspection, and repair of components such as heat exchangers and valves.

Comparison and Application Considerations:


Building Type and Size: Heat pumps are well-suited for standalone buildings or properties with sufficient outdoor space for installation, while HIUs are more commonly used in multi-unit buildings or developments connected to district heating networks.

Energy Efficiency Goals: Heat pumps offer higher energy efficiency and lower carbon emissions compared to HIUs, making them suitable for buildings seeking to achieve higher environmental standards.

Infrastructure Availability: The availability of district heating networks and central heat sources may influence the choice between heat pumps and HIUs, with HIUs being more feasible in areas with existing district heating infrastructure.

Both heat pumps and heat interface units offer valuable heating solutions for buildings in the UK, each with its own set of features, benefits, and challenges. Heat pumps provide the highest energy-efficient heating with low carbon emissions, making them ideal for standalone properties and buildings seeking high environmental standards. On the other hand, heat interface units enable the integration of centralized heating systems, offering much higher flexibility, space-saving benefits, and efficiency optimization in multi-unit buildings connected to district heating networks or apartment block CHP system. The choice between heat pumps and HIUs depends on factors such as building type, energy efficiency goals, and infrastructure availability, and careful consideration of these factors is essential for selecting the most suitable heating solution for each application.

At Wavin, our purpose is to build healthy sustainable environments. Our tailored indoor climate solutions feature our market leading systems and products including underfloor heating, heat interface units, MVHR and single controls (interfacing with all of these technologies). They provide the following benefits:

  • Improved energy efficiency
  • Low maintenance
  • More space and design freedom
  • Compatible with all floor types and coverings
  • Comfortable environments with even heat and less dust
  • Full zone control
  • Flexible solutions including installation and after-sales support
  • Design and system selection support
  • Wavin’s extensive experience in residential projects as the market leader in Europe