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Field performance of domestic heat pumps for heating and hot water in Switzerland: insights and analysis.

Number: 2296

Author(s) : KUSTER R., PRINZING M., BERTHOLD M., ESCHMANN M., BERTSCH S.

Summary

This study presents recent results, analysis, and optimization of heat pump field trials as they are currently carried out by the Heat Pump Test Center (WPZ) in Buchs, Switzerland. In the current study, heat pumps for hydronic heating systems in mainly single-family houses within Switzerland have been investigated since 2016. So far, 24 air-source and geothermal heat pumps have been added to this governmental quality assurance program (SFOE). For each heat pump system, approximately 40 measured variables are recorded at a time interval of 10 s with calibrated sensors with very low measurement uncertainty.
This field study aims to record the real system efficiency in operation and to draw comparisons with characteristic values from laboratory measurements and manufacturer data. This work presents meaningful data and results of the current field study as well as a detailed analysis of the investigated heat pump systems. Due to digitalization and short sampling intervals, temporal processes in heat pump systems can be investigated in detail, enabling comprehensive analysis and comparison.
More than 70 % of the installed heat pumps in Swiss households are air-sourced. Thus, the performance of most heat pumps in Switzerland is strongly influenced by the outside temperature. Geothermal heat pumps, on the other hand, benefit from a more stable source temperature. Geothermal heat pumps show a 4 K higher average source temperature (8.1 °C) during operation compared to air-source heat pumps (4.3 °C) for heating and DHW production. Remarkable differences in source temperature and thus performance were also found between existing and newly installed geothermal systems. Besides installation issues also control concepts have been evaluated based on the measurement data. Such control concepts allow air-source heat pumps to be advantageous compared to geothermal heat pumps in some examples.
The comparison of variable speed systems to conventional on/off heat pumps shows a significant difference in efficiency and controls strategies, but for example, the standby power consumption of inverter systems must be considered quite critical, since several heat pump systems show unnecessarily high losses. In one example, a detailed analysis of the measurement data revealed a permanently high standby power loss of about 50 W, which resulted in lower system efficiency.

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  • Original title: Field performance of domestic heat pumps for heating and hot water in Switzerland: insights and analysis.
  • Record ID : 30030649
  • Languages: English
  • Subject: Technology
  • Source: 2022 Purdue Conferences. 19th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2022

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