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CFM Formula:
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CFM (Cubic Feet per Minute) calculation for ductwork determines the volume of air flow through ventilation systems. It's essential for proper HVAC system design, ensuring adequate air circulation and maintaining indoor air quality.
The calculator uses the basic CFM formula:
Where:
Explanation: This formula calculates the volume of air moving through a duct per minute based on the speed of the air and the size of the duct opening.
Details: Accurate CFM calculation is crucial for proper HVAC system design, energy efficiency, maintaining comfort levels, and ensuring adequate ventilation for health and safety standards.
Tips: Enter air velocity in fpm and duct area in ft². Both values must be positive numbers. For rectangular ducts, calculate area as width × height. For circular ducts, use π × radius².
Q1: What is a typical velocity range for ductwork?
A: Residential systems typically range from 600-900 fpm, while commercial systems may operate at 1,200-2,000 fpm depending on application.
Q2: How do I measure duct area?
A: For rectangular ducts: measure width and height in inches, convert to feet (divide by 12), then multiply. For circular ducts: measure diameter, calculate radius, then use π × radius².
Q3: Why is CFM important in HVAC design?
A: CFM determines the system's capacity to heat, cool, and ventilate spaces properly. Incorrect CFM can lead to poor air quality, discomfort, and energy waste.
Q4: What factors affect CFM requirements?
A: Room size, occupancy, heat-generating equipment, building insulation, and local climate all influence CFM requirements for proper ventilation.
Q5: Can this calculator be used for both supply and return ducts?
A: Yes, the same formula applies to both supply and return air ducts, though CFM requirements may differ between them in a balanced system.