Which system to choose?
There are two principal methods for supplying thermal energy to the source-side loop in GSHP applications:
(a) Closed loop systems, in which the source-side loop is long, and is buried in the earth, either: i. as coils of HDPE pipework to depths of > 1.5m in cut-and-fill trenches, or ii. suspended in vertical boreholes.
(b) Open loop systems, in which the source-side loop is covered in pumped groundwater, which is typically re-pumped to the subsurface via another borehole well after passing through the heat pump.
In both cases, the energy source generally approximates to the local average annual air temperature, which in the lowland UK is typically between 10°C and 12°C. The fluid in the source-side loop will typically be chilled to around 6°C after passing through the heat exchanger. The exchanger typically delivers heat at around 55°C. The system can be coupled to closed circuits of water pipes supplying conventional 'wet' radiators or underfloor heating systems. The under floor heating been the system far better suited to ground source heat pump applications.