Geothermal Heat Pump Systems Part Three – System Options

Last month, in part two of our series, we shared some tips about getting started with design and construction of a geothermal heat pump system by conducting a formation thermal conductivity test.

The next step is to understand the different design options available for the system. There are two distinct types of heat pumps that can be used in a geothermal system — a water-to-air system and a water-to-water system. Both types use the earth as its means of rejecting and reclaiming heat; however, the processes for accepting and rejecting heat are different for each. In a water-to-water system, the heat is accepted and rejected into a water pumping system before being transferred to an air distribution system; whereas, in a water-to-air system, the heat is accepted and rejected directly into an air distribution system.

Identifying the type of system that is right for your facility depends on the nature of your project and the conditions of your facility. For existing facilities, replacing an existing chilled/hot water system with a geo­thermal, water-to-water system may be the right choice as long as the piping infrastructure is sound. For a new facility, installing a water-to-air system may make more sense since it eliminates the need for an ad­ditional heat exchange process. In either case, it is important to analyze the exact application to make sure that the system makes sense from a cost, energy efficiency and performance standpoint.

In part four of our series on geothermal heat pump systems, issued next month, we will identify key things to look for once your system is installed and fully operational.

In the meantime, if you have any questions about geothermal systems, please contact Roger Thies, PE at or (814) 237-2180.

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