Features Geothermal
NGWA publishes new geothermal heat pump system guidance

Westerville, OH – The National Ground Water Association has released new guidelines on the impact of hydrogeology on large-scale geothermal heat pump systems that provide details on site and hydrogeologic considerations and site constraints.

The guidelines, entitled Understanding Hydrogeology and Its Impact on Large-Scale Geothermal Heat Pump Systems, have been published by NGWA Press, the association’s publishing arm. They are edited by industry experts Nina Baird, PhD, Carnegie Mellon University, and John Rhyner, PG, P.W. Grosser Consulting Inc., and provide a useful ongoing reference for those involved in planning or site assessment for a large-scale GHP project, the association said in a news release.

While site geology and ground water hydrogeology strongly influence the feasibility and cost-effectiveness of a geothermal heat pump (GHP) system, these are often the least-understood aspects of an installation. NGWA prepared these guidelines to support installation and ongoing operation of high-performance GHP systems with focuses on the protection of groundwater and the optimal performance of the wellfield.

Design and installation of a large-scale GHP system requires multidisciplinary expertise to evaluate underlying geology, climate, meteorology, hydrogeology, drilling conditions, the building loads, and the ongoing thermal interdependence that will affect the ground heat exchanger (GHX) and building systems simultaneously. Topics covered in the book therefore address:

• Fundamentals of large-scale systems
• Site and hydrogeologic considerations
• Site constraints
• Site assessment and ground coupling options
• Drilling
• Regulations and requirements
• Professional qualifications for GHP system design and installation
• Characteristics of a successful GHP product
• Common causes of GHP shortfalls.

The text is designed for anyone who is considering or involved in the installation of large-scale GHP systems, including owners, planners, architects, engineers, drilling contractors, mechanical contractors, government representatives and educators.