Case study: Old Watermill

This renovated Watermill utilises the water source that used to power the mill to now provide heat to the building, thanks to a network of coiled slinky pipe buried in the riverbed.

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The client objective was to harvest renewable heat using renewable electricity generated from an old restored water mill. Kensa Heat Pumps supplied an 8kW heat pump with slinkies. The heat pump draws electricity from a 60kW hydro turbine and provides 100% of the space heating load for 150m2 of the restored mill. A further 79m2 is heated using waste heat from the generator and turbine switchgear.

The slinkies were buried approximately 200mm under a riverbed in river gravel. This method of installation was favoured by the client for a number of reasons, including reduced cost of installation due to removing the need for digging trenches. Other benefits to the client for utilising water as the energy source include improved efficiency of the heat pump due to the higher heat transfer rate achieved when using water as the energy source, compared to burying the slinkies in the ground.

The building was effectively a complete rebuild, only the walls remained standing. It was ideal for wet under floor heating to be installed throughout the property. The underfloor heating was installed under 75mm of Ecoscreed which is made from ground recycled glass and powerstation flyash used as the binder. This is 100% recycled material and has considerable better conductivity than conventional screed.

Since completing the renovation, installing and commissioning the water source heat pump, the property is partly let out as a commercial office and partly used as domestic studio accommodation. The client commented that the comfort levels within the property are “excellent”.

We have never been too hot or too cold – The comfort levels are excellent.

Key Facts

  • Restoration of an Old Watermill
  • 8kW Kensa Single Compact heat pump
  • 100% space heating with underfloor heating
  • Slinky Coils laid 200mm underwater in riverbed