Ground Loop Systems
There are two types of ground loop systems:
The system incorporates a vertical borehole with a single U shaped plastic pipe loop that circulates a heat transfer fluid such as glycol. These loops are usually installed at depths of up to 150metres. The finished borehole is completed with a special heat conductive grout which encases the loop from top to bottom.
The heat transfer fluid is circulated round and round the system via the Heat Pump, never leaving the pipe network but gaining or losing energy to the ground.
Larger systems require a series of such boreholes and loops to be combined in a manifold which enables these multiple boreholes to be returned back to a single flow for onward transmission and connection to the Heat Pump.
All sub-surface joints are completed using fusion welding and are pressure tested before backfilling to ensure the pipework remains leak-free.
These systems require water from a waterwell, lake or river to provide the heat source and do not recycle heat transfer fluid. The abstracted groundwater is circulated directly through the heat pump and then used as part of a grey water system, discharged to a surface water system or simply discharged back underground. A second borehole may be required if a discharge to groundwater is used. Normally, due to the high volumes involved, it may be necessary to obtain abstraction licences. Generally open loop systems are more economical on larger projects.