How often has an AHU or system been reused as part of a building renovation project and/or to expand the area served by the associated unit to provide additional air conditioning or heating? It happens probably everyday somewhere, and yet I can’t say I have ever seen a design checklist to standardize the process and to help ensure the successful reuse of a unit and/or system.
Here is an example of reusing a central air system where the building owner’s design engineer convinced the owner to keep the duct distribution system and purchase a new, larger capacity AHU.