What is a unique feature of a geothermal single pass system?

A geothermal single pass system is characterized by its design to discharge water on the surface of the ground. This unique feature distinguishes it from other geothermal systems that typically operate in a closed-loop configuration, where water is continuously circulated through a sealed system without any discharge to the environment.

In a single pass system, water is taken from a source—such as a body of water or groundwater—used for heating or cooling, and then returned back to the environment. This approach can simplify installation and maintenance, particularly in systems where the water source is readily available and can support this direct discharge method without ecological concerns.

The options that describe sealed loop systems or those that require installation below ground are representative of closed-loop geothermal systems, which are different in operation and installation requirements. Additionally, while geothermal systems can be common, the designation of "most common" does not specifically define the single pass system's distinctive feature as effectively as the discharge aspect does.