heat pump field tests, seasonal performance factors, annual coefficient of performance, domestic hot water, state of the art
This study presents the development, the methods, and the state of the art of heat pump field trials as they are currently carried out by the Heat Pump Test Center (WPZ) in Buchs SG, Switzerland. In the current study, heat pumps for hydronic heating systems in single family houses within Switzerland have been investigated since 2016. So far, over 20 air-source and geothermal heat pumps have been added to this governmental quality assurance program (Swiss Federal authority EnergieSchweiz). For each heat pump system, more than 40 measured variables are recorded at a time interval of 10 s using calibrated sensors with very low measurement uncertainty. The aim of this field study is to record the real system efficiency in operation and to draw comparisons with characteristic values from laboratory measurements and manufacturer data. The study presented is divided into two parts. The first part entitled “Technology, Methods and State of the Art of the field studies” focuses on the procedure and measuring technology of field studies performed at WPZ Buchs. The second part is entitled “Results, Analysis and Optimization of current field studies” and presents meaningful results of the current field study as well as identification and optimization of possible deficiencies in the planning, installation and handling of the investigated heat pump systems. Heat pumps installed in new and refurbished buildings have been investigated with different system boundaries. In terms of performance, the current study shows an average annual coefficient of performance (SPF) of 3.6 and a span from 3.5 to 3.7 for floor heating and domestic hot water production using air/water heat pumps. Geothermal heat pump systems reach an average annual coefficient of performance of almost 5. Although the systems are running quite satisfying overall, the results also show considerable differences between the systems as well as typical mistakes in the installation and handling of the heat pumps. A controller that does not work optimally in terms of application and consumption is a frequently found cause of decreased performance. After evaluating the baseline performance for two years, the systems are optimized to increase performance and avoid poor operation. The collected data is also used to better define guidelines for planner and installers.