1. What is HVAC Airflow Calculation?

Definition: This calculator determines the required airflow (in CFM) for an HVAC system based on heat load and temperature difference.

Purpose: Helps HVAC professionals and engineers properly size ductwork and select equipment for heating and cooling systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q_{cfm} \) — Airflow (cubic feet per minute)
• \( Q_{btu} \) — Heat load (BTU per hour)
• \( \Delta T \) — Temperature difference (°F)
• 1.08 — Constant for air at standard conditions

Explanation: The formula calculates how much air needs to be moved to transfer the specified amount of heat given the temperature difference.

3. Importance of Airflow Calculation

Details: Proper airflow calculation ensures efficient system operation, adequate heating/cooling capacity, and proper humidity control.

4. Using the Calculator

Tips: Enter the heat load in BTU/h and temperature difference in °F. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What does the 1.08 constant represent?
A: It's the product of air's specific heat (0.24 BTU/lb-°F) and density (0.075 lb/ft³) × 60 min/hour.

Q2: What's a typical ΔT for heating systems?
A: Usually 30-70°F for forced air systems, but varies by system design.

Q3: How do I find the heat load for my space?
A: Use Manual J calculations or consult HVAC design software/professionals.

Q4: Does this work for cooling calculations?
A: Yes, but for cooling you must also consider latent heat and humidity.

Q5: What if my system uses different air density?
A: Adjust the constant (1.08) proportionally for different air densities.