Air source heat pumps have not always been suitable for retrofit applications. Robert Lockhart looks at how new developments are changing this.
With carbon reduction targets to meet and huge rises in gas and electricity prices, it's no wonder that renewable technologies are becoming an increasingly attractive proposition. Air source heat pumps, for example, deliver energy savings and higher efficiency ratings than traditional technologies, but also attract financial assistance through the Renewable Heat Premium Payments.

Air source heat pumps work by extracting heat from the surrounding atmosphere, which is then passed over a heat exchanger. It is during this process that it is upgraded to a higher, more useful temperature.

Existing air source heat pump technologies have generally been promoted as a solution for new builds. This is because they produce a lower grade of heat than other technologies, meaning underfloor heating is the best output for this thermal energy. This is less than ideal for existing buildings, as it requires a lot of work to install an underfloor heating system.

In addition, there has been some scepticism about the effectiveness of heat pumps, particularly when retrofitted to an existing system and during cold periods.

With these issues in mind, manufacturers have continued to research and develop heat pump technology, allowing these solutions to become almost as adaptable as gas boilers. The most significant advancement is the introduction of inverter technology and sophisticated temperature controls, which now enable a heat pump to continuously react to the UK's changing climate and user habits.

Installing a new inverter-driven air source heat pump is relatively straightforward, helping to reduce time on site which is always a benefit. Very little ground work is required, other than the provision of a sound and level base. While there are split systems available, where one part is located outside and the other indoors, plug and play systems are easier to install. In fact, these can be fitted by a heating engineer or contractor, rather than a refrigerant engineer. This said, it's recommended that a relevant heat pump course is attended.

With this in mind, those considering moving into air source heat pumps installations should think about becoming MCS approved. Being MCS accredited is likely to be a huge advantage, as most customers will choose those who are accredited for reassurance, as well as to gain access to funding from the forthcoming Renewable Heat Premium Payment (RHPP) scheme. Part of the criteria for end users to qualify for the RHPP is that the installation is carried out by an MCS accredited installer or contractor.

At a time when the construction of new buildings is on the decline, and budget cuts are necessary alongside reductions in carbon emissions, existing building stock has to be improved. Advances in technology are making it easier to use renewable heating systems within the existing framework of a property, resulting in reduced carbon emissions, fuel savings, and lower overheads. With the ease of installation for retrofit projects, it is now much simpler to upgrade existing building stock with air source heat pumps and reap the benefits of this sustainable technology.

• Robert Lockhart is Vokera's renewables sales manager