Daily Code Talk #17 – IMC 202: General Definitions That Trigger Redlines

🧠 Plain English Breakdown These definitions change what you owe in design, submittals, and inspections. Five high-impact ones:Appliance vs Equipment • Appliance = manufactured device that uses energy and is directly regulated. • Equipment = system components (ducts, vents, piping, controls). 👉 Listings/MI bind appliances; system performance/specs bind equipment.Air-Handling Unit vs Air-Conditioning System vs Air Distribution System • AHU = the blower/fan box. • Air-conditioning system = AHU + coils/filters + ducts. • Air distribution system = ducts/plenums/equipment that move air. 👉 Label precisely to avoid scope/testing/listing confusion.PlenumAn enclosed building portion intentionally used as part of the air distribution system. 👉 Triggers material limits, wiring/insulation ratings, and fire/smoke coordination.Fire Damper / Smoke Damper / Combination Fire = stops flame; Smoke = stops smoke; Combination = both. 👉 The wrong device in a rated assembly is a guaranteed inspection delay.Ceiling Radiation Damper (CRD)Listed device at penetrations of rated floor/ceiling or roof/ceiling assemblies to limit radiative heat transfer at air openings. 👉 CRD ≠ fire damper.🏗️ Why It Matters in Design & Construction Misused definitions = wrong clearances, wrong damper, wrong plenum materials, RFIs, failed inspections, and schedule hits.🔧 Field TipAdd this on your cover sheet and in Division 01 – General Requirements:“Definitions per IMC Chapter 2; if undefined, see IBC/IFC/IFGC/IPC; if still undefined, use commonly accepted meaning per IMC 201.4.”Want my Definition Control Kit (cover-sheet note, Division 01 clause, 10-item “term-collision” checklist)? Comment “TERMS.”Need quick eyes on a set? DM “ADVISORY.”