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Duct Area 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 system performance, and energy efficiency.
The calculator uses the duct area formula:
Where:
Explanation: This formula calculates the required duct area based on the desired airflow rate and air velocity. Proper duct sizing is essential for maintaining system efficiency and minimizing pressure drops.
Details: Correct duct sizing is crucial for HVAC system performance. Undersized ducts can cause reduced airflow, increased energy consumption, and system strain. Oversized ducts may lead to poor air distribution and increased installation costs.
Tips: Enter CFM (cubic feet per minute) and velocity (feet per minute). Both values must be positive numbers. The calculator will compute the required duct cross-sectional area in square feet.
Q1: What is the recommended air velocity for residential HVAC systems?
A: For residential systems, recommended air velocity is typically between 600-900 ft/min for main ducts and 500-700 ft/min for branch ducts.
Q2: How does duct shape affect the calculation?
A: This calculator provides cross-sectional area. For rectangular ducts, you'll need to determine appropriate width and height dimensions that provide the calculated area.
Q3: What factors besides CFM and velocity affect duct sizing?
A: Other factors include duct material, system static pressure, duct length, number of bends, and temperature of the air being moved.
Q4: Can this calculator be used for both supply and return ducts?
A: Yes, the same formula applies to both supply and return ducts, though velocity recommendations may differ between them.
Q5: What is the relationship between duct size and system efficiency?
A: Properly sized ducts reduce friction losses, maintain designed airflow, and help the HVAC system operate at peak efficiency, reducing energy costs.