Btu/h To Cfm Calculator

CFM from BTU/h Formula:

\[ CFM = \frac{BTU/h}{1.08 \times \Delta T} \]

CFM (Cubic Feet per Minute):

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1. What is the BTU/h to CFM Conversion?

The BTU/h to CFM conversion calculates the required airflow (in cubic feet per minute) needed to transfer a specific amount of heat energy (in BTU per hour) given a temperature difference. This is essential for HVAC system design and sizing.

2. How Does the Calculator Work?

The calculator uses the standard HVAC formula:

\[ CFM = \frac{BTU/h}{1.08 \times \Delta T} \]

Where:

\( CFM \) — Cubic Feet per Minute (airflow rate)
\( BTU/h \) — British Thermal Units per hour (heat transfer rate)
\( 1.08 \) — Constant derived from air density and specific heat
\( \Delta T \) — Temperature difference in degrees Fahrenheit

Explanation: The formula relates heat transfer capacity to airflow volume, accounting for the thermal properties of air at standard conditions.

3. Importance of CFM Calculation

Details: Accurate CFM calculation is crucial for proper HVAC system design, ensuring adequate airflow for heating and cooling loads, energy efficiency, and occupant comfort.

4. Using the Calculator

Tips: Enter BTU/h value (heat load), temperature difference in °F (between supply and return air). All values must be positive and valid for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What does the 1.08 constant represent?
A: The constant 1.08 is derived from the density of air (0.075 lb/ft³) and specific heat of air (0.24 BTU/lb·°F) at standard conditions: 60.075 × 0.24 = 1.08.

Q2: What are typical CFM requirements?
A: Typical residential systems require 400-2000 CFM depending on home size, while commercial systems can range from 2000-50,000+ CFM based on building use and size.

Q3: How does temperature difference affect CFM?
A: Larger temperature differences require less CFM to transfer the same amount of heat, while smaller temperature differences require more CFM.

Q4: Is this formula accurate for all conditions?
A: This formula assumes standard air conditions (sea level, 70°F). For high altitudes or extreme temperatures, adjustments may be needed for air density changes.

Q5: Can this be used for both heating and cooling?
A: Yes, the formula works for both heating and cooling applications, though temperature difference interpretation may vary (heating: supply-return, cooling: return-supply).