What type of units must heating panels be unless otherwise labeled?

Heating panels are classified as complete units unless specified otherwise. This designation means that they are designed to function as standalone systems that include all necessary components for their operation, such as controls and connections. Being a complete unit ensures that the panel complies with the standards and regulations set by the North Carolina Mechanical Code, providing the needed efficiency and safety in heating applications.

In the context of the code, having a complete unit simplifies installation, maintenance, and inspection processes, as it is designed to operate correctly without requiring additional parts or modifications. Utilizing complete heating panels minimizes risks associated with improper installations or missing components, promoting overall system reliability and safety.

The other options suggest different characteristics or configurations that do not align with the established standard for heating panels under the code requirements. Thus, considering the definition and implications of heating panel classifications within the North Carolina Mechanical Code, "complete" is indeed the appropriate designation unless stated otherwise.