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Rectangular Duct Area Formula:
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Rectangular duct size calculation determines the cross-sectional area required for proper air flow in HVAC systems based on the air volume (CFM) and desired velocity.
The calculator uses the formula:
Where:
Explanation: The formula calculates the required duct area to maintain the desired air velocity for a given airflow rate.
Details: Proper duct sizing is crucial for efficient HVAC system operation, ensuring adequate airflow, minimizing pressure drops, and reducing energy consumption while maintaining comfort levels.
Tips: Enter CFM (cubic feet per minute) and desired velocity in ft/min. Both values must be positive numbers. The calculator will provide the required cross-sectional area in square feet.
Q1: What is the typical velocity range for HVAC ducts?
A: Typical velocities range from 600-2000 ft/min for supply ducts and 500-1500 ft/min for return ducts, depending on the application and noise considerations.
Q2: How do I convert area to actual duct dimensions?
A: Once you have the required area, you can choose appropriate width and height dimensions that multiply to equal the calculated area while maintaining proper aspect ratios.
Q3: What factors affect duct sizing besides CFM and velocity?
A: Other factors include duct material, length, number of bends, static pressure, and system efficiency requirements.
Q4: Why is proper duct sizing important?
A: Proper sizing ensures efficient airflow, reduces energy costs, minimizes noise, and prevents system strain that can lead to premature equipment failure.
Q5: Can this calculator be used for round ducts?
A: This calculator provides area for rectangular ducts. For round ducts, you would need to calculate diameter from the area using the circle area formula.