Thought HVAC installation may occur as part of a larger project, it is ubject to its own specific regulation and permit process.
Apart from the HVAC permit per se, certification is frequently required in relation to the capacity of an existing structure to support the load of new equipment.
Partial images of sample drawings for some actual HVAC Structural Support are included below. 
Drawings may not be reproduced; And, they are only to be used for the project and site identified in the drawing set.