What defines self-contained equipment in heating, air-conditioning, or refrigeration?

Self-contained equipment in heating, air-conditioning, or refrigeration refers specifically to machinery that has all of its operational components housed within a single unit. This design encapsulates the entire system, making it compact and relatively easy to install and maintain. A self-contained unit doesn’t require additional external parts or components to function effectively, which streamlines operation and reduces the complexity involved in setup and service.

In contrast, the other options describe different characteristics of equipment. Removable components suggest a modular design that allows for convenience during maintenance but doesn’t imply that the unit operates as a single, enclosed system. Similarly, modular systems that can be expanded indicate that individual components can be added or removed for capacity adjustments, which is not a feature of self-contained units. Lastly, equipment that requires separate components for assembly contradicts the very nature of self-contained systems, as these systems are designed to function as standalone units without reliance on external parts.