PHAM NEWS | SEPTEMBER 2024 Renewable Energy


Advice on retrofi tting air source heat pumps


Successfully integrating an air source heat pump into an existing property requires some careful planning. Here, Mike Pryde from Grant UK provides some guidance on some of the key considerations when retrofi tting heat pumps into a home which may previously have used a gas or oil system.


only in new builds but also in existing or older properties. Retrofi tting these systems off ers homeowners a low carbon, effi cient alternative to traditional boilers. However, successfully integrating a heat pump into an older property involves careful planning and a clear understanding of the specifi c challenges associated with such installations. ASHPs operate diff erently from traditional high-


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temperature systems like gas or oil boilers. Heat pumps are low- temperature systems, meaning they work more effi ciently in well-insulated homes where heat loss is minimised. As an installer, it is crucial to collaborate closely with homeowners to understand their heating requirements, comfort levels and hot water usage, as these factors will heavily infl uence the system design.


Calculating heat loss The fi rst step in any retrofi t project is to assess the property’s suitability for a heat pump installation. This involves a thorough heat loss calculation to determine the building’s heating demands. Factors like the age of the property, its construction materials, insulation levels and existing heating infrastructure must be considered. For example, homes with single- glazed windows or poor


R290 refrigerant Air source heat pumps use refrigerants to help them convert heat energy from the air outside to provide heat inside our homes. For the last few years, R32 refrigerant has been commonly used in heat pumps. But as heat pump technology has evolved, the type of refrigerant used in some heat pumps is also changing, with an example being the use of R290 refrigerant.


As well as being a more


ir source heat pumps (ASHP) are becoming increasingly popular, not


insulation will likely need upgrades before a heat pump can be installed eff ectively. Improving the energy


effi ciency of the property by adding double glazing, upgrading insulation or even implementing other measures like draught-proofi ng, is essential. These upgrades not only enhance the comfort of the home but also ensure that the heat pump can operate effi ciently, maintaining a stable temperature while minimising energy consumption.


Mike Pryde


Grant UK’s regional sales manager for North of England and Scotland


Sized to fi t


Each project is unique, and it is vital to design the system based on the specific


characteristics of the property


Once the property’s heating requirements are established, the next step is to design the heating system. The system must be carefully tailored to meet the specifi c needs of the property. This includes selecting the appropriate heat pump size and output, as well as specifying the correct type and size of heat emitters. In many cases, larger or more effi cient radiators or a retrofi t underfl oor heating system, may be required to complement the lower water temperatures used by heat pumps.


The system’s pipework might also need to be upgraded. For example, larger diameter pipes and enhanced insulation could be necessary to ensure effi cient heat distribution throughout the property. However, not every retrofi t


will require such extensive changes. Each project is unique, and it is vital to design the system based on the specifi c characteristics of the property.


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The key steps While every retrofi t heat pump installation will be diff erent, there are key steps that installers should follow because thorough planning and installation is crucial for ensuring the long-term performance of the heat pump system: • Heat Loss Calculation: Conduct a detailed heat loss calculation to understand the property’s heating requirements. • System Design: Choose the correct heat pump size and type, along with suitable heat emitters, based on the calculated heat loss and homeowner preferences. • Installation: Ensure the heat pump and all associated components are installed correctly, adhering to


manufacturer guidelines and best practices. • Handover: Provide a


comprehensive handover to the homeowner, including detailed instructions on how to operate and maintain the system. By following these steps, installers can ensure that the heat pump operates at its highest effi ciency, providing the homeowner with a sustainable and cost-eff ective heating solution.


Hybrid systems


environmentally friendly refrigerant, R290 off ers a range of other benefi ts to heat pumps. R290 has excellent thermodynamic properties which enable it to capture heat energy and release it again in a very eff ective way within a heat pump, which in turn makes the system itself very effi cient. The Grant Aerona 290, which will be launched in October, achieves an A+++ ErP energy rating at 35°C fl ow temperature while also operating with ultra- low noise levels.


In some cases, a standalone heat pump might not be feasible due to high heat loss or the impracticality of upgrading the heating emitters. For these situations, hybrid systems off er a fl exible alternative. A hybrid system combines a heat pump with a traditional boiler, allowing the heat pump to handle the majority of the heating demand while the boiler provides additional support when needed.


Our EvoLink Hybrid System Hub is an example of such technology, enabling the integration of an air source heat pump with existing boilers, whether they are gas, LPG or oil-fi red. This system can signifi cantly reduce the property’s carbon emissions and dependency on fossil fuels, making it an attractive option for homeowners who are not yet ready to fully transition to renewable heating. ◼ phamnews.co.uk/924/31


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