Heat interface units (HIUs) are a fantastic heating solution to effectively and efficiently distribute heat within a property, and is part of a heat network . In this blog we put HIUs under the microscope starting with the basics and exploring key considerations for installation. We’ll also take a closer look at one HIU in particular which has set a new standard in the industry for its responsiveness, efficiency and ease of installation.
But first, let’s take a deeper dive to truly understand exactly what a heat interface unit is.
Understanding heat interface units
Ultimately, a heat interface unit is an essential part of any communal or district heating system. Used most frequently in apartment blocks and flats, it is responsible for providing the hot water and heating within a property through a network of pipes that are connected to one central system.
HIUs completely replace the need for a traditional gas boiler, as each property will have its own HIU installed so that supply can be provided to the occupant on demand.
Unlike gas boilers, HIUs are more energy efficient as the entire building uses one large low carbon heat source, such as a large scale heat pump more effectively – which means HIUs can also dramatically reduce the amount of carbon emissions produced from blocks of flats and residential properties in the UK.
A HIU is an incredibly effective heating system which provides high quality heat and hot water with little disruptions or issues to the residents.
Introducing the Wavin Calefa heat interface unit
As mentioned above, a HIU is installed into each individual property within a residential building and replaces the traditional gas boiler.One system in particular, which has been specially engineered by Wavin to truly optimise hot water delivery is Calefa.
Calefa HIU
Originally developed in Denmark, the home to district heating units, Calefa sets incredible new standards for the delivery of domestic hot water because of its responsiveness, efficiency and ease of installation.
It is a complete, fully insulated in-direct district-heating unit that can be used in heat networks or district heating systems with heat exchangers for regulation of the flow temperature.
Through the 4-option bypass control, the user has a choice of setting the keep-warm to on, off, on a specific schedule – which means they can pick when they want the system to be turned on – or auto mode.
When in auto mode, the electronic control unit monitors the usage of the domestic hot water,, and then uses this insight to learn the specific usage patterns for that home. With this intelligence, the system can make sure that the hot water is always ready to use at these specific times.
Fig 2. Electronic Control Unit
Operating in this way helps to reduce the overall energy consumption for each individual property, as well as the whole building. This is because the system will only bypass hot water when needed rather than throughout the entire day.
Thanks to the specially designed 4-option bypass control, the Calefa, which already delivers a very low VWART will reduce the energy used by even more during low demand periods . The auto function makes Calefa truly unique and sets a completely new standard for domestic hot water delivery in the UK.
How is the performance of heat interface units measured?
The performance of district heating heavily relies on the efficiency of a HIU and so the Building Engineering Services Association (BESA) launched test standard in 2016 to help verify how well the HIU works under typical UK operating conditions.
The aim of the test is to calculate the annual Volume Weighted Average Return Temperature (VWART) for domestic hot water use, space heating and keep-warm functions. This is completed by mimicking the demand the HIU might see in a typical year, and the results reflect how the system performs in different modes.
Ultimately, the lower the VWART, the lower the average return and therefore, any HIU which gets these results is incredibly high performing.
When independently tested by BESA, Calefa recorded a VWART of 31ºC, which is 2ºC below the CP1-Code of Practice recommended level
The tests reveals the unit achieved 45ºC domestic hot water temperature within 11 seconds, with stable control of the hot water in varying temperature scenarios. The space heating supply was stable across varying loads, temperatures, and pressures, demonstrating a high performance level in the likely scenarios a HIU will operate at.
How can the heat interface unit be controlled?
Wavin have engineered Calefa to make sure that it works in synergy with the Warmafloor underfloor heating control system, Sentio.
This is another advantage for homeowners who are then able to control the domestic hot water temperature through the app. As well as being able to control the hot water, control the bypass, or heating on remotely, users will also receive pressure loss notifications so they’re always aware of how the system is functioning.
What are the considerations for setting up and installing Calefa?
Designed with the installer and homeowner in mind, Calefa has been engineered as a complete system which couldn’t be easier to handle and install, set-up, service and maintain.
The HIU can simply be wall-mounted with the appropriate fixings in two easy access keyholes. Once the connections are made, there’s no need for any programming, as once the system is turned on, the control unit starts automatically and is ready to use after just a few seconds.
The system’s electronic control unit also helps to simplify any future services or maintenance as it delivers fault-finding diagnostics so engineers know what the problem is at a first glance.
Intelligent HIU with a Unique Control System
Unlike anything else in the market, Calefa is a completely unique system which is not only incredibly simple for installers to set up, but it also gives homeowners the ability to control how they use their domestic hot water and heating.
Able to achieve incredible results, this heat interface unit is the most effective and efficient in the market. To discover more, get in touch with our team of professionals today.
Alternatively, if you need some additional support on your next project, we can help you to select the system that’s most suitable for your requirements.
Indoor Climate Solutions at Wavin
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 market leader in Europe
