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WP2 - Testing (Deliverable 2.2)

The full report is confidential and will not be distributed to the public. However, a brief summary of the contents are given here.

This Deliverable describes the selection and testing of the state of the art systems that will serve as a reference for the MacSheep project. One ground source system and one air source system have been selected for the test, based on several criteria such as:

  • On the market and sold in larger quantities today.
  •  Can be considered “up to date” concerning recent developments.
  •  Fits the reference load defined for the system test.

The heat pump of both selected systems used Scroll compressors and did not apply double stage compressor cycles, economizer cycles or desuperheaters. The air source system used a speed controlled compressor, since it was found that this is the current trend for air source systems and that many air source systems are sold already today with this technology. The collectors are flat plate collectors, and the storage tanks are solar combi-storages with internal DHW heat exchangers and internal solar heat exchangers. Both systems were tested in the system test benches between November 2012 and January 2013.

For both systems, a performance factor was calculated based on the useful heat delivered for domestic hot water and space heating divided by total electricity demand over the 12-days test. Thus, the storage and system losses are included in these figures and reduce the performance compared to other seasonal performance factor definitions. For the ground source system, this value was 4.2, for the air source system 2.7. Both results are below expectations. This may be due to the hydraulics and control of the heat pump integration into the systems that resulted in heat quantities delivered from the heat pump in domestic hot water mode (flow temperatures of 45 – 55 °C) that were considerably higher than the heat delivered from the combistore to the domestic hot water supply. For these reasons, the most obvious system design problems are corrected for in annual simulations, and the (better) simulation results will then be used as a benchmark for the state of the art system that the MacSheep developments will be compared against.

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