1. What is AHU CFM?

AHU CFM (Air Handling Unit Cubic Feet per Minute) measures the volume of air flow through an air handling unit. It's a critical parameter in HVAC system design and performance evaluation.

2. How Does the Calculator Work?

The calculator uses the CFM formula:

Where:

• \( BTU/hr \) — British Thermal Units per hour
• \( \Delta T \) — Temperature difference in degrees Fahrenheit
• \( 1.08 \) — Constant factor for air density and specific heat

Explanation: This formula calculates the cubic feet per minute of air flow required to transfer a specific amount of heat energy (BTU/hr) given a temperature difference.

3. Importance of CFM Calculation

Details: Accurate CFM calculation is essential for proper HVAC system sizing, energy efficiency optimization, and ensuring adequate air circulation for comfort and air quality.

4. Using the Calculator

Tips: Enter BTU/hr value and temperature difference in °F. Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What does the 1.08 constant represent?
A: The 1.08 constant accounts for the density of air (0.075 lb/ft³) and the specific heat of air (0.24 BTU/lb-°F), combined as 0.075 × 0.24 × 60 = 1.08.

Q2: What is a typical CFM range for residential AHUs?
A: Residential AHUs typically range from 600-2000 CFM, depending on the home size and HVAC system capacity.

Q3: How does CFM affect HVAC system performance?
A: Proper CFM ensures efficient heat transfer, adequate air distribution, and maintains desired temperature and humidity levels throughout the space.

Q4: Can this formula be used for cooling calculations?
A: Yes, the same formula applies for both heating and cooling calculations, as it's based on heat transfer principles.

Q5: What factors can affect CFM requirements?
A: Building size, insulation quality, climate zone, occupancy, and equipment efficiency all influence the required CFM for optimal performance.