Vertical Grouted Geo Borehole (field)

One method to exchange thermal energy with the earth is a multi-bore, vertical loop field, sized to serve the geothermal heat pump equipment inside the building.  Grouted boreholes range from 150-to-500 feet in depth and are spaced least 15 feet apart.  Once the closed loop fluid’s piping (serving as a heat exchanger) drops 20 feet underground, the earth’s temperature is unchanged, year round.

The illustration graphic depicts passage of the loop fluid (brine) in series, through the piping in each borehole.  The preferred method is to use horizontal supply and return headers.  From the supply header, some of the passing brine is directed into only one borehole before returning to the inside of the building via a return header.  Because of this, any unit of brine fluid pulls heat from (heating) or rejects heat to (cooling) only one borehole.  This preserves the physics of the greatest temperature difference (ΔT) between the overall brine volume and the temperature of the formation into which it is introduced.  Greater temperature differences drive the mechanism of thermal conduction—and this is precisely what geothermal heat pumps are designed to exploit.