Project - Energy efficient tap water heat pump

Per Henrik Pedersen

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Project - Energy efficient tap water heat pump

Energy Efficient Tap Water Heat Pump

Project start January 2012. Ended April 2014.

Purpose of project
The purpose of the project is to develop a tap water heat pump with af 30% better COP in collaboration with Vesttherm, Danfoss, EBM Papst, IPU/DTU and DONG. The tap water heat pump delivers warm tap water to households and summer homes and will replace electric water heaters. The goal is that the product should be placed in the top energy class in the future EU energy efficient label scheme for water heaters, and additionally live up to the most strict ecodesign requirements.

The heater strives to make use of natural refrigerants (hydrocarbon), which is in contrast to existing products. The new model will be competitive, both in regards to efficiency and cost, in comparison to other heating systems. The tap water heat pump has to be able to adapt to future flexible power supply and should be able to run when there is excess energy.

As a spin off of the project is will be aimed to enable the product to become more known in the general public, in order to make sure that the product becomes an option when seeking to reduce energy consumption in Danish homes. Furthermore, there will be worked on the possibility to connect the heater to solar heat, since the control of this should be an integrated part og the heat pumps operation strategy.

The project participants are aware of the possibility of making the product more energy efficient and the new possibilities that enable these are, among others:

  • The use of rotation compressor (instead of stamp compressor)
  • The use of variable speed drives
  • A better air flow above evaporator and use of new efficient ventilators


The project is divided into 9 phases:

  1. Charting the market and retrieving an update of potential from existing literature.
  2. Define needs and the size of the product. In this phase alterations in EU's energy efficient label scheme and the Ecodesign requirements are explored.
  3. Map out technical possibilities. A 'state of the art' for existing product is developed, and the newest technologies on the market are reviewed. Especially new kinds of compressors and ventilators are examined. Furthermore, new types of heat exchangers are looked into, in order to achieve an increase in effieciency.
  4. A calculation program is set-ip and ideas for prototypes are worked on.
  5. The prototype is built.
  6. The existing heat pumps and the new prototype are tested in a climate chamber at Teknologisk Institut and the results are analysed.
  7. In this phase the prototype is modified and a new test is carried out. A test report is made.
  8. A small field test is undergone at three specific users in collaboration with DONG.
  9. Lastly, an analysis is made on the energy efficiency, impact on the environment, economy and competitiveness and the project is reported to Dansk Energi.


  • Danish Technological Institute - Per Henrik Pedersen (project leader)
  • Vesttherm A/S
  • EBM Papst
  • Danfoss GmbH
  • Dong (og 3 brugere)

Funded by ELFORSK - part of Dansk Energi.