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HVAC Duct Area Formula:
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The HVAC duct size calculation formula (A = CFM/V) calculates the required cross-sectional area of ductwork based on airflow rate (CFM) and air velocity (FPM). This ensures proper airflow distribution in HVAC systems.
The calculator uses the duct area formula:
Where:
Explanation: The formula calculates the required duct area to maintain proper air velocity for efficient HVAC system operation.
Details: Proper duct sizing is crucial for efficient HVAC operation, ensuring adequate airflow, minimizing energy consumption, reducing noise, and maintaining comfort levels throughout the building.
Tips: Enter CFM (cubic feet per minute) and V (feet per minute) values. Both values must be positive numbers greater than zero for accurate calculation.
Q1: What is the recommended air velocity for HVAC ducts?
A: Recommended velocities vary by application: 600-900 FPM for main ducts, 600-700 FPM for branch ducts, and 500-600 FPM for residential systems.
Q2: How does duct shape affect the calculation?
A: The formula calculates area. For rectangular ducts, you'll need to determine appropriate width and height dimensions that provide the required cross-sectional area.
Q3: What are typical CFM requirements for residential systems?
A: Typical residential systems require 400-600 CFM per ton of cooling capacity, but this varies based on specific design requirements.
Q4: Why is proper duct sizing important?
A: Undersized ducts increase static pressure and noise while reducing airflow. Oversized ducts increase installation costs and may cause air distribution problems.
Q5: Should I consider other factors besides area?
A: Yes, also consider friction losses, duct material, layout complexity, and system static pressure for complete duct design.