The short answer to this question is yes, an air source heat pump can be retrofitted into an existing or older property. However, to ensure that the heat pump can work efficiently to fulfil the heating demand of older properties, installers must ensure sufficient energy efficiency measures are in place and that the system has been accurately designed. This blog explores the topic of retrofitting heat pumps and the important installation steps installers need to follow.
Demand for efficient heating systems is growing with homeowners looking for new central heating systems which are not only effective but also more sustainable. Air source heat pumps are an example of a low carbon, efficient heating system which are growing in popularity with more and more heating engineers expanding their skills in order to fit new heat pump into their customers’ homes. Heat pumps are suitable for installation in lots of types of homes, not just new builds, so in this blog we will explain more about retrofit installations, looking at how heat pumps can be fitted into existing homes and the steps installers can take to develop their knowledge in retrofitting heat pumps.
What is retrofitting?
In the heating sector, the term retrofitting refers to installing a new heating system into an existing property. While new builds account for a significant proportion of heat pump installations each year, the retrofit market is considerable and if net zero carbon targets are going to be achieved, the carbon footprint of heating systems in existing homes must be reduced. The retrofit market also offers installers opportunities to grow their businesses by being able to offer more sustainable heating systems to homes and households looking to replace their traditional boiler and upgrade their home heating.
Retrofitting a heat pump
It is important to emphasis that retrofitting a heat pump is not the same as fitting a replacement boiler. Air source heat pumps are low temperature systems and therefore work very differently to high temperature systems, such as a gas or oil boiler. This means that when planning the installation of a new heat pump for an existing property, installers must work closely with their customers to ascertain their temperature preferences, comfort levels and hot water usage as well as thoroughly assessing the heat loss of the property. With thorough planning and correct system design, retrofitting a heat pump can provide your customers with a modern, highly energy efficient heating system with sustainable and environmentally friendly benefits as well.
Depending on the age of a property, its build material, its insulation levels and its size, retrofitting a heat pump may involve changes to the wider heating system. For example, if a property has single glazed windows or poor levels of wall insulation, it would be recommended for energy efficiency measures, such as double glazing or cavity wall insulation, to be carried out prior to a heat pump being installed. This is because you want to mimimise the amount of heat that can escape a home, which in turn will support the heat pump’s ability to operate efficiently to fulfil the space heating demand of your customers’ homes.
It may also be necessary to increase the surface area of the heat emitters within the property which can be achieved by fitting larger radiators, installing radiators which are better suited to low temperature systems (such as aluminium radiators) or by fitting a retrofit underfloor heating system. The system pipework may also need to be upgraded with larger pipe and improved insulation. However, it is important to stress that not every retrofit heat pump installation will require all of these changes – every installation is different and this is why it is imperative to plan each installation based on a property’s individual requirements and specification.
When it comes to installing an air-to-water heat pump, whether it is a retrofit installation, part of an extension or wider renovation, or a new build, heat pump installers should follow each of these steps:
- Carry out a thorough heat loss calculation for the property
- Accurately design the system, selecting the correct heat pump output and size and specifying appropriate heat emitters (Grant UK has an in-house Design Team who can help with heat loss calculations and system specifications)
- Correctly install the new heat pump system
- Complete a thorough handover of the system with the end-user or customer.
To learn more about heat pump installations and what is involved, please read our blog about the best practices for installing heat pumps.
Can you add a heat pump to an existing boiler?
Yes, a new air source heat pump can be installed to work alongside an existing fossil fuel boiler when fitted with hybrid technology, such as the Grant EvoLink Hybrid System Hub. For some properties, it may not be suitable for a standalone heat pump to be fitted – this may be because the heat loss is too high or the option to install upgraded heat emitters is not feasible. However, by installing the heat pump as part of a hybrid system, the household can benefit from having a proportion of their heating and hot water demand being fulfilled by renewable energy, helping them to reduce their dependency on fossil fuels.
The Grant EvoLink is a white cased, wall mounted unit which houses the hydraulics needed to connect an Aerona³ R32 air source heat pump with most types of existing boilers, from gas boilers, LPG boilers and oil boilers. If you have customers who have a traditional boiler but are looking at ways to reduce their carbon emissions and lower their reliance on fossil fuels, the EvoLink provides the solution to add a renewable heat pump to an existing system. The EvoLink will control both the boiler and the heat pump, using the heat pump to fulfil as much of the heating and hot water demand as possible and using the boiler as a supplementary heater.
Please click here to learn more about the Grant EvoLink Hybrid Hub, including details about free online training about this product.
Where can heat pumps be installed?
It is a misconception that heat pumps are only suitable for new builds. As explained in our blog about heat pump myths, heat pumps can be installed into many types of homes, retrospectively fitted to replace an old heating system. This can include larger buildings such as farmhouses, properties currently with a gas central heating system, or renovated properties to give just a handful of examples. You can read learn more about these types of retrofit heat pump installations in our case studies below:
Aerona³ 10kW heat pump upgrades Wiltshire farmhouse heating system
Grant renewable heating system helps family reduce their energy costs
Aerona³ heat pumps take heating to a new level
As mentioned earlier in this blog, retrofit installations can involve additional measures to ensure the property is suitable for a heat pump and this will depend on the insulation levels of the walls, roof and windows, the outdoor space available for siting the heat pump, and the size of the property and its heating and hot water demand. To learn more about what properties are air source heat pumps suitable for, please visit our Knowledge Hub.
How to become a heat pump installer
In June 2024, NESTA published the findings of their heat pump installer survey which revealed that 87% of respondents wanted to increase the number of heat pumps they install each year (NESTA, 2024). The survey also indicated that employers prefer to hire more experienced staff and expect a much higher level of practical heat pump installation experience. A good place to start, therefore, for experienced heating engineers and those at the beginning of their careers in the heating sector is heat pump product training.
Heat pump product training courses provide installers and engineers with an introduction to heat pumps, how they operate and include the opportunity to get hands-on experience with heat pump units. At Grant UK’s Training Academy, for example, the heat pump training courses combine theory with practical learning to equip installers with the confidence to apply their learning out in the field. For installers looking to gain MCS accreditation for heat pumps, in order to be eligible for heat pump installations under the Boiler Upgrade Scheme, industry qualification courses will be of interest. This includes the OFTEC OFT21-504A qualification for the installation, commissioning and servicing of air source heat pumps, which enables installers and engineers to apply for OFTEC heat pump registration and for MCS certification for work carried out under the scope of MIS 3005-I.
Grant UK, providing air source heat pump
training courses
Here at Grant UK, we deliver air source heat pump training throughout England, Scotland and Wales. Alongside our heat pump training helping heating professionals to install, commission and service heat pumps, our Trainers also provide other product training on hybrids, solar thermal systems, underfloor heating and hot water storage. Our Training Academy HQ in Swindon, Wiltshire, is also an approved OFTEC training centre, delivering OFTEC heat pump qualifications and assessments. The facilities include practical workshops, interactive screens and air-conditioned theory rooms as well as dedicated assessment areas.
Start your journey into heat pumps today - learn more about our award-winning Training Academy and discover the comprehensive range of Grant air-to-water heat pumps and accessories as well.