What are mechanical systems called that were installed before the adoption of the current code?

The term "Existing Mechanical Systems" is used to refer to mechanical systems that were put in place prior to the adoption of the current code. This designation indicates that the systems may not be up to date with newer regulations or standards, but they are still recognized as functional and valid installations.

Existing Mechanical Systems are often subject to specific provisions within the code, allowing for the continued use of these systems while also addressing safety and efficiency. This classification helps inspectors and professionals assess compliance during inspections, especially when evaluating if modifications, maintenance, or replacements are necessary to align with current regulations.

The other terms describe different circumstances. For instance, "New Mechanical Systems" would imply installations that adhere to the most recent standards. "Legacy Mechanical Systems" is sometimes used informally to indicate older systems, but it is not the standard terminology in code context. "Retrofitted Mechanical Systems" refers to older systems that have been updated or modified to meet newer standards, which is distinct from simply being "existing."