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CFM Formula:
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CFM (Cubic Feet per Minute) is a measurement of airflow volume, indicating how many cubic feet of air pass through a specific point in one minute. It is a crucial parameter in HVAC system design and analysis.
The calculator uses the CFM formula:
Where:
Explanation: The formula calculates the volume of air moving through a duct by multiplying the air velocity by the cross-sectional area of the duct.
Details: Accurate CFM calculation is essential for proper HVAC system design, ensuring adequate ventilation, maintaining indoor air quality, and optimizing energy efficiency in residential, commercial, and industrial buildings.
Tips: Enter velocity in feet per minute (fpm) and duct area in square feet (ft²). Both values must be positive numbers. For rectangular ducts, area = width × height. For circular ducts, area = π × (diameter/2)².
Q1: What is a typical CFM range for residential HVAC systems?
A: Typical residential systems range from 400-2000 CFM, depending on the size of the home and system capacity.
Q2: How do I measure air velocity in a duct?
A: Air velocity is typically measured using an anemometer or pitot tube at multiple points across the duct cross-section for accurate averaging.
Q3: Why is CFM important in HVAC design?
A: CFM determines the system's ability to provide adequate heating, cooling, and ventilation while maintaining comfort and indoor air quality standards.
Q4: What factors affect CFM requirements?
A: Room size, occupancy, heat loads, building orientation, insulation levels, and local building codes all influence CFM requirements.
Q5: Can CFM be too high or too low?
A: Yes, excessive CFM can cause noise and drafts, while insufficient CFM can lead to poor temperature control, humidity issues, and inadequate ventilation.