Ground-source heat pump ground-loop system piping must be marked where the piping does what?

The correct answer pertains to the requirement that ground-source heat pump ground-loop system piping must be marked where it enters a building. This marking is essential for several reasons.

Firstly, marking the entry point helps in ensuring proper identification of the system components, which is crucial for maintenance and emergencies. Knowing where the ground-loop piping enters the building allows technicians to quickly locate the system for any service requirements, repairs, or inspections, minimizing downtime and maximizing efficiency.

Additionally, appropriate markings at the point of entry can assist in preventing accidental damage during construction or renovation activities. If other trades understand where these pipes are located, they can take care not to disrupt them, which could lead to failures in the HVAC system.

Though options concerning other points—such as where the piping exits the building or connects to the heat pump—are important, the point where the piping enters the building is critical for visibility and safety, thus fulfilling the code's intent to promote efficient system operation and maintain safety standards.