Groundwater heat pump systems using an isolation heat exchanger and separate production and injection wells are covered in this paper. Guidelines are provided and procedures are described for the calculation of well pump head, system performance (system EER and system COP), optimum groundwater flow, and required production/injection well separation distance along with well pump control strategies. Related issues necessary to place these issues in context, including water well terminology, well flow testing, and alternate open-loop system types, are also introduced. Finally, a spreadsheet for accommodating the necessary calculations is presented.Units: Dual