HVAC engineers

Basic HVAC Duct Design Calculation Proper duct design is essential for maintaining required airflow and system efficiency in HVAC systems. One of the key steps is calculating the required duct size based on airflow (CFM). Step 1: Airflow Requirement (CFM) Airflow is determined based on room cooling load. CFM = Cooling Load (BTU/hr) ÷ (1.08 × △T) Step 2: Select Air Velocity Typical duct air velocity range: * Main duct: 1200-1500 FPM * Branch duct: 600-900 FPM Step 3: Duct Area Calculation Duct Area = CFM + Velocity Example: Required airflow = 2000 CFM Selected velocity = 1200 FPM Duct Area = 2000-1200 Duct Area = 1.67 ft² Now we can select the nearest duct size from standard duct dimensions. Example duct size: 24" x 10" duct ≈ 1.67 ft² Accurate duct sizing ensures proper air distribution, reduces pressure loss, and improves HVAC system efficiency.