The Energy Saving Trust in the UK is calling on industry to improve installation techniques for air and ground source heat pumps to ensure they become a quality and mainstream technology for householders. This follows the completion of the first phase of the most comprehensive field trial of the technologies ever undertaken in the UK, which studied heat pumps at 83 sites (54 ground source and 29 air source.)
The trial began in early 2009 and monitored both technical performance and customers’ experiences for a full 12 month period. Results show that a number of heat pump installations performed very well, achieving an overall system efficiency rating of three and above – this means for every unit of electricity put in there is an output of three units of heat.
The sample of ground source heat pumps had slightly higher measured system efficiencies than the air source heat pumps. The ‘mid-range’ system efficiencies were between 2.3 and 2.5, with the highest figures reaching over 3.0. Despite this, the system efficiency figures for the sample of ground source heat pumps were lower than those monitored in similar European field trials.
The ‘mid-range’ of measured system efficiencies for air source heat pumps were near 2.2 and the highest figures in excess of 3.0.
The conclusions of the trial are:
1 Heat pumps are sensitive to design, commissioning and use. The field trial covered a variety of early installations, many of which failed to correctly design and/or install the heat pump. This result emphasises the need for improved training for installers.
2 Keep it simple. There were many system configurations monitored in the field trial. In most cases, the simplest designed systems performed with higher efficiencies.
3 The impact of domestic hot water production on system performance is unclear. Heat pumps can be designed to provide domestic hot water at appropriate temperatures, but more investigation is needed to determine the factors which have an impact on system efficiency.
4 Heating controls for heat pump installations have to be comprehensively reviewed. There has been a failure to explain proper control requirements to both installers and heat pump customers.
5 Responsibility for the installation should be with one company, and ideally be contractually guaranteed to ensure consistency in after-sales service.
6 Further study needs to be undertaken on an installation-by-installation basis, to record what has been done wrongly (or correctly), what could be done better, and what exactly should be done in the future.
The Energy Saving Trust will act as a leading member of a working group made up of leading industry players and Government to make recommendations for improvements to training and installation standards within six months. The improvements will include:
* Creating new guidelines for installers on best practice skills and training.
* Reviewing the Microgeneration Certification Scheme for heat pumps to include product and installation standards.
The Energy Saving Trust is the UK’s leading impartial organisation helping people save energy and reduce carbon emissions.