GEOTHERMAL - Vertical (closed loop)

Vertical Loop:
Systems consist of drilling a 4” diameter (typically) bore hole, inserting a high density polyethylene pipe with a “U” bend on the bottom (so the pipe is continuous) and grouting the hole with a grouting sealer. The grouting sealer helps prevent ground water from flowing into different aquifers at different levels, preventing surface water from running down the hole and creating a thermally conductive medium between the pipe and sides of the borehole.

 

 

 

 

Bore Hole Depths:
A rule of thumb for bore hole depths is 200 ft. (70 meters) for each ton of heat pump. This is a rule of thumb only and WILL vary depending on site layout, heat pump size, etc.

Heat Sink:
A water based liquid (with environmentally friendly glycol) is pumped through the loops – the heat migrates to (accepts heat from the ground – heating mode) or from the liquid (deposits heat to the ground – cooling mode). In other words the ground is used as a heat sink. Heat can be rejected in the summer and be extracted in the winter.

Geothermal DX (Direct Exchange System):
Sometimes called Direct Expansion Systems. A direct “earth coupled heat pump” (“DX “) is similar to the liquid vertical loop except DX uses refrigerant to  extract heat from the earth in heating mode and reject heat to the earth in cooling mode. The advantages of DX systems are less drilling/trenching thus reducing costs, greater heat transfer through refrigerant grade copper (well beyond HDPE –high density polyethylene pipe), smaller diameter bore holes, excellent for existing properties with limited access or finished landscape areas (less disruption) and eliminating circulating pumps (required for liquid systems).

Refrigerant escaping into the ground is not an issue for refrigerant vaporizes and rises – therefore it will not stay in the ground to pollute aquifers etc. As with all air conditioning refrigerants, due to concerns for the ozone layer, refrigerant must be handled by qualified technicians.