Heating Engineering

New energy-saving pump drives for solar power plants and heating technology

At present, pump systems for solar power plants and heating systems utilise electromechanical energy converters with an asynchronous motor system (AC motor). These are inefficient. As part of the research project, the project partners develop a motor with a permanent magnet (EC motor) with variable output. This motor is highly efficient, especially in the low output range from 10 to 1,100 W. 



In Germany, the more than 30 million heating circulation pumps contribute a substantial 3.5% of the nationwide electrical energy consumption. Existing heating systems today usually use a low-maintenance canned motor pump with an AC motor. However, their low efficiencies of 7 to 30% (in the output range up to 50 W) can be improved upon only to a limited degree. 

Numerous new installations are expected, particularly in terms of solar thermal energy. Most commonly, these use only slightly modified AC systems based on heating technology even though solar pumps are operated under different boundary conditions (smaller volume flows, greater delivery heights, discontinuous circulation with sometimes short cycle times etc.). From a primary energy viewpoint, they consume up to a quarter of the solar yield. Prototype solar pumps with EC motors are expected to be substantially more efficient while retaining the same level of reliable operation. 

The project partners thus face the task of further optimising drive systems for small heating pumps using EC motors with an output of 10 to 50 W and to perform field testing to investigate their viability. Furthermore, the development of a new generation of pumps based on the innovative and efficient EC motor system for the output range from 10 to 1,100 W was planned.


  • At the low output of 10 W, the prototypes developed display a three times higher efficiency. Inn the higher output range up to 1,000 W, the efficiency is doubled.
  • A product range specifically for heating systems was developed unto series maturity.
  • Compared to their predecessors, the new pumps' weight has been reduced by around fifty percent, facilitating further energy and emission savings during product distribution.
  • The systems developed have been equipped with IT interfaces, thus offering optimisation potential through adjusted control, which in turn allows further energy savings.

Project Participants

Implementing Institution

WILO SE - Abt. Technischer Service

More Project Informations

Project number:  0329715B

Project period:  1999 - 2001

Project region:  Germany (North Rhine-Westphalia)

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Source: German National Library of Science and Technology Hannover (TIB)