Replace with your HVAC estimating or system layout training video.

• Mechanical specs define ductwork sizes, types (flex/rigid), gauge, insulation, and hangers.
• Always check the air device schedule for CFM, throw patterns, and collar sizes.
• Rooftop units and split systems often reference other disciplines for power and support.
• Pay attention to control sequences — these affect what’s included in Division 23 vs Division 26.
• Include condensate piping, roof penetration details, and mechanical startup procedures in estimates.

1. What types of duct materials are typically outlined in Division 23?
   Answer: Flexible and rigid ducts, with details for gauge, hangers, and insulation type.
2. What should you verify on the air device schedule?
   Answer: CFM, throw pattern, collar size, and installation notes for each grille, diffuser, or register.
3. What other divisions may be referenced for rooftop or split systems?
   Answer: Division 05 (for structural supports) and Division 26 (for power and disconnects).
4. Why is the HVAC control sequence important for estimators?
   Answer: It determines who is responsible for controls wiring and startup — HVAC or electrical.
5. What scope items are often missed related to condensate piping?
   Answer: Roof penetrations, piping slope, and connection details — plus startup tasks like flushing and pressure testing.

Division 23: Heating, Ventilating & Air Conditioning (HVAC)

🔹 Key Teaching Points

1️⃣ Ductwork Specifications

• Specs outline duct types (flex vs. rigid), sizing, gauge, hangers, and insulation.
• Be sure to match mechanical plans with spec requirements for material takeoff accuracy.

2️⃣ Air Device Schedule Review

• Each diffuser, grille, and register has CFM, throw pattern, and neck/collar size requirements.
• Schedule discrepancies lead to performance and installation issues — double-check them!

3️⃣ Rooftop Units & Split Systems

• Specs often cross-reference structural (curbs/support) and electrical (power feeds/disconnects).
• Include all pads, curbs, and rigging requirements in your estimate — don't assume it's "by others."

4️⃣ Controls & Scope Coordination

• Control sequences help determine what belongs to HVAC vs. Electrical (Division 26).
• For DDC/BAS systems, specs may outline controls vendor responsibilities in detail.

5️⃣ Condensate Piping & Startup

• Include all condensate drains, roof penetrations, and sloped piping.
• Startup procedures (flushing, pressure testing, commissioning) are often in the last spec sections.

✅ Wrap-Up Summary

• Division 23 outlines every component of an HVAC system — from duct gauge to commissioning tasks.
• Always cross-reference power, support, and control scope with Divisions 26 and 05.
• Accurate estimating means accounting for both visible and behind-the-scenes mechanical elements.