Correct set-up of air-to-water heat pumps, installing user-friendly controls and, perhaps most importantly, time spent educating end-users helps ensure customers maximise the full benefits, says Stuart Gadsden.
Air-to-water heat pump systems are an efficient, practical and proven solution for providing heating and hot water in both new build and refurbished housing. Developers, social landlords, homeowners and tenants are sold on the fact that these systems can dramatically reduce carbon emissions and cut utility bills, when compared with traditional systems.
But however well a renewable heating and hot water system is designed and installed, it is vital that the end-user understands how their system works and how to maximise its energy efficiency. Therefore, not only does the system need to be set up correctly during commissioning, the controls also have to be as user-friendly as possible and the end-user must understand how a heat pump system operates differently to a conventional fossil fuel boiler. When commissioning any heat pump system, the controls should be set up to maximise efficiencies. For example, the heat pump should be set up to deliver the lowest possible water temperature to the heat emitters while still maintaining comfort levels.
[box type=”success” align=”aligncenter” ]The heat pump should deliver the lowest possible water temperature to the heat emitters while maintaining comfort levels.[/box]
This can typically be achieved by using weather compensation so that there is a higher water temperature when it is cold outside and a lower water temperature when it is warm. It is important to explain this to the end-user so that they understand why the temperature of the radiators changes throughout the year.
Hot water priority
As heat pump systems are typically designed to give hot water priority over space heating, hot water timer periods should, wherever possible, be set during times when the space heating demand is likely to be low – for example, in the early hours of the morning. This will ensure the heat pump is available for space heating when required.
Where there is a back-up heating source, such as an electric heater or boiler, this should also be programmed only to come on when absolutely necessary. More advanced heat pumps can include a bi-valent control option and can be programmed to limit the back-up heater to only operate below a certain ambient temperature. When it comes to user programming, it is important that controls are clear and simple – using text rather than symbols on an easy-to-read screen. A controller that also displays energy usage, such as the new controller for Daikin Altherma’s improved Low Temperature Split air-to-water heat pump range (see panel), is a good choice.
An energy usage display can help the end-user optimise the settings of the system to achieve higher efficiencies. However, it is worth considering restricting end-user access to the controller to just a few key functions. This will avoid unnecessary tampering, which could result in inefficient operation of the heat pump. Once the system is installed and commissioned, it is crucial to ensure that the end-user understands fully how their new system works, the technology behind it and how to get the best out of it. For a start, end-users can be sceptical about the concept of ‘free heat from the air around us’.
So, despite the fact that air-to water heat pumps can keep a house warm all winter with high levels of comfort, while reducing heating bills, some customers still need convincing that they will work in UK conditions. A simple experiment, such as asking a customer to take a bicycle pump outside on a cold day, pump it a few times and then touch the end – can demonstrate that even ‘cold’ air has latent heat in it. Customers also need to adjust to the idea that running their new system at a lower temperature for longer periods is more efficient and effective than if it is on for short bursts at higher temperatures – particularly important if heat emitters have changed from traditional radiators to underfloor heating.
The latest revision to the Microgeneration Certification Scheme (MCS) Microgeneration Installation Standard, MIS 3005 v3.1a, may help.Under the new standard, installers must keep the end user fully informed throughout both the design and installation stages. System designers also have to provide a full explanation of the running cost estimates, including system pumps, cylinder losses, use of immersion heaters for hot water and so on. The new Heat Emitter Guide can helpexplain the impact of emitter selection and design flow temperature on the estimated heating system efficiency.
Most heat pump manufacturers provide technical support and training to customers. Daikin UK, for example, understands thatswitching to renewable energy requires a change of culture and has run a number of workshops for social housing providers and their tenants to ensure that systems are set up correctly and explained properly. Renewable energy’s profile has increased over the last few years but many customers still do not fully understand the new technology and how it might work for them. Open dialogue throughout design and installation, user-friendly controls and a clear explanation of how the system works can only help improve the performance of systems and enhance their reputation. This should also help convince others to choose renewable energy for their homes in the future.
[author image=”https://www.installeronline.co.uk/wp-content/uploads/2012/12/StuartGadsden.jpg” ]Stuart Gadsden is a qualified environmental engineer with a PhD in renewable energy. He has worked in the heat pump industry for five years, starting as operational manager for an installation company, and is now a heat pump product specialist at Daikin.[/author]