1. What is an Air Conditioning CFM Calculator?

Definition: This calculator estimates the required air flow (CFM) for an air conditioning system based on cooling capacity and temperature difference.

Purpose: It helps HVAC professionals and engineers determine proper airflow for efficient cooling system operation.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q_{cfm} \) — Air flow (cubic feet per minute)
• \( Q_{btu} \) — Cooling capacity (BTU per hour)
• \( \Delta T \) — Temperature difference between supply and return air (°F)
• 1.08 — Constant that accounts for air density and specific heat

Explanation: The cooling capacity is divided by the product of the temperature difference and the constant 1.08 to determine required airflow.

3. Importance of CFM Calculation

Details: Proper CFM calculation ensures efficient heat transfer, proper dehumidification, and optimal system performance.

4. Using the Calculator

Tips: Enter the cooling capacity in BTU/h and temperature difference (default 20°F). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical ΔT for residential AC?
A: Most systems are designed for 18-22°F temperature difference between supply and return air.

Q2: How do I find my system's cooling capacity?
A: Check the equipment nameplate or specifications. 1 ton of cooling equals 12,000 BTU/h.

Q3: Why is 1.08 used in the formula?
A: It's derived from the specific heat of air (0.24 BTU/lb-°F) and standard air density (0.075 lb/ft³), converted to minutes.

Q4: Does this account for humidity?
A: This basic formula doesn't account for latent heat (humidity). For precise calculations, consider the enthalpy difference.

Q5: What if my actual CFM is different from calculated?
A: Check for duct restrictions, improper fan speed, or incorrect system sizing if actual CFM differs significantly.