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HVAC Duct Size Formula:
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HVAC duct sizing is the process of determining the appropriate cross-sectional area for air ducts in heating, ventilation, and air conditioning systems. Proper duct sizing ensures efficient airflow, balanced pressure, and optimal system performance.
The calculator uses the duct sizing formula:
Where:
Explanation: The formula calculates the required duct area based on the desired airflow rate and velocity. Proper velocity selection depends on the application and noise considerations.
Details: Correct duct sizing is crucial for efficient HVAC operation. Undersized ducts increase static pressure, reduce airflow, and decrease system efficiency. Oversized ducts can lead to poor air distribution and increased installation costs.
Tips: Enter CFM (cubic feet per minute) and desired air velocity (ft/min). Typical velocities range from 600-900 ft/min for residential systems and 1000-2000 ft/min for commercial systems.
Q1: What is the recommended velocity for residential HVAC systems?
A: For residential systems, velocities typically range from 600-900 ft/min for supply ducts and 500-700 ft/min for return ducts.
Q2: How does duct shape affect sizing calculations?
A: Round ducts are more efficient than rectangular ducts. When using rectangular ducts, the equivalent round diameter should be calculated first.
Q3: What factors influence CFM requirements?
A: CFM requirements depend on room size, heat load, number of occupants, and the specific HVAC system capacity.
Q4: Are there limitations to this calculation method?
A: This is a basic calculation that doesn't account for friction losses, duct material, or complex system layouts. Professional HVAC design requires more comprehensive calculations.
Q5: How do I convert square feet to round duct diameter?
A: For round ducts: Diameter = 2 × √(Area/π). For a given area, this calculates the equivalent round duct diameter.