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The History of Heat Pump Technology

The History of Heat Pump Technology

Many people still believe that heat pump technology is a recent innovation and, on this basis, are concerned that the systems may be unproven or at an early stage in their evolution. The truth however is that heat pump technology has been established for more than 150 years and the first ground source heat pump was brought into use more than 70 years ago.

It was way back in 1948 that J Gordon Cook wrote in The Spectator magazine:

“In these days of material progress, when so much lip-service is being paid to science as our guarantee of prosperity, it seems incredible that a device such as the heat pump should have escaped the attention it deserves. Had it not been for a team of enthusiasts determined to carry their theories into practice, we should have been still awaiting evidence of the potentialities of the heat pump in Britain. Now we know that it will work, and the time has come when everything must be done to make the most of the knowledge we have gained.”

The following gives a brief overview of the development of this technology to the reliable and efficient heating systems that are built by established companies such as Lämpöässä today.


  • 1748: William Cullen demonstrates artificial refrigeration.
  • 1834: Jacob Perkins builds a practical refrigerator with diethyl ether.
  • 1852: Lord Kelvin describes the theory underlying heat pump.
  • 1855–1857: Peter von Rittinger develops and builds the first heat pump.
  • 1945: John Summer builds a full scale water source heat pump in Norwich
  • 1983: Lämpöässä build their first heat pump in Lapua, Finland

The first heat pump as we know it today was built by Peter von Rittinger in 1856. He recognised the principle of the heat pump while conducting experiments on the use of water vapour’s latent heat for the evaporation of salt brine. As a result, in Austria the heat pump was used to dry salt in salt marshes.

The first large scale heat pump in the UK was developed by John Sumner in 1945 on the doorstep of Finn Geotherm in Norwich. The Norwich City Council Electrical Department had built new premises in Norwich at Duke Street, on the bank of the River Wensum. The office was originally intended to be heated by a heat pump, but the wartime austerity prevented resources being available to focus on such an innovative project. After the war however John Sumner, who was the City Electrical Engineer for Norwich, “cobbled together” a system from salvaged parts based on a SO2 refrigerant. The system is reputed to have achieved a seasonal efficiency ratio of 3.42. The system ran at an average thermal delivery of 147kW and had a peak output of 234kW. The system was designed to circulate water around the building’s heat emitter systems at 50-55°C. Despite the efficiency and effectiveness of the system it was not widely copied in the UK because of the relative cheapness of fossil fuels such as coal and later North Sea oil and gas.

John Sumner also installed a closed loop ground source heat pump for his home in the early 1950s. The ground loop was initially constructed using copper pipe buried at around 1m depth and was filled with circulating antifreeze. Whilst Sumner’s heat pumps were totally effective and, for their time, technically brilliant, they received little support in the UK, where abundant coal seemed to provide a cheap and limitless source of energy.

As is so often the case however, UK technical advances were adopted and developed overseas. In 1948 a large scale heat pump was installed in Oregan in the United States. Following the OPEC oil crisis of the 1970s however the development and adoption of heat pumps began to gather pace. Sweden in particular was developing new atomic reactors and was looking for efficient means of heating homes with electricity rather than paraffin.

During this period closed loop polythene systems became the norm, with vertical closed loop systems being developed in Germany, Switzerland and in Finland through the work of companies such as Lämpöässä. By 2008 it is estimated that Switzerland alone had between 30,000 and 44,000 GSHP units. In the United States wide scale adoption had progressed even faster. It is estimated that by 2008 the US market was installing between 50,000 to 60,000 units per annum with a total of some 750,000 units being in operation by 2008.

Suomen Lämpöpumpputekniikka Oy (known to its friends as Lämpöässä) was established in Lapua on 29th March 1983, based on the craftsmanship of five men and decades of expertise in geothermal heating. The company had its first office at Jorma Saksi’s home but later moved to rental premises at the reception hall along Härsiläntie road. The first year also saw the implementation of a significant assignment, the heating system of Ruha school. Lämpöässä has now supplied more than 20,000 heat pumps to its customers around Europe and has some 4,000 units on its service data base that are more than 30 years old and are still going strong.

The development of heat pump technology is still continuing with advances in compressor and controls technology in particular enabling systems to be more efficient and easier to control. Heat pump technology is reliable, effective, efficient and is here to stay! In the words of Gordon Cook in 1948:

“There can be no doubt that in the heat pump we have a machine that is to play an outstanding part in the industrial future of our country.”

In a beautiful close to the historic circle, the Eastern Electricity Building at Duke’s Street in Norwich is about to be redeveloped to provide 154 residential units as well as commercial and retail space. One of the central planning conditions of the Duke’s Wharf development is that it should incorporate a water source heat pump. The current specification is for a system with a maximum capacity of around 800kW, with the River Wensum once more being used as the heat source. We think John Sumner would have approved!