National Ground Water Association

(WESTERVILLE, OH — June 30, 2011) Mechanical engineers, architects, developers, HVAC contractors, and others involved in geothermal heat pump installations should evaluate the qualifications of drilling contractors to protect groundwater and optimize heat pump system operation.

The National Ground Water Association has developed a list of pertinent questions professionals should ask drilling contractors. The list can be accessed at NGWA’s Wellowner.org Web​ site.

Estimates by the HVAC industry suggest that as much as 50 percent of the total geothermal heat pump market involves the use of vertical borehole subsystems. There are several different configurations of geothermal heat pump system installations involving vertical Earth drilling:

• Open loop — single well for water withdrawal, water returned to a surface source
• Open loop — single well for water withdrawal, water returned to a second well
• Standing column — single well for water withdrawal and water return
• Closed loop — vertical boreholes
• Direct exchange (DX) — vertical boreholes using concentric pipe systems.

Experienced geothermal heat pump installers confirm that it is critical these systems (1) be installed with a properly constructed borehole, (2) equipped with a properly placed loop tube assembly, and (3) have properly grouted boreholes, not only for optimal heat transfer but also for groundwater protection.

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NGWA, a nonprofit organization composed of U.S. and international groundwater professionals — contractors, equipment manufacturers, suppliers, scientists, and engineers — is dedicated to advancing groundwater knowledge. NGWA’s vision is to be the leading groundwater association that advocates the responsible development, management, and use of water.

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