Btu H To Cfm Calculator

BTU/h to CFM Formula:

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

CFM (Cubic Feet per Minute):

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1. What is 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 British Thermal Units 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)
\( BTU/h \) — British Thermal Units per hour (heating capacity)
\( \Delta T \) — Temperature Rise in degrees Fahrenheit
\( 1.08 \) — Constant derived from air density and specific heat

Explanation: The constant 1.08 accounts for the specific heat of air (0.24 BTU/lb·°F) and the density of air (0.075 lb/ft³) at standard conditions, multiplied by 60 minutes per hour.

3. Importance of Airflow Calculation

Details: Proper airflow calculation is crucial for efficient HVAC system operation, ensuring adequate heating/cooling capacity, preventing equipment damage, and maintaining comfortable indoor environments.

4. Using the Calculator

Tips: Enter BTU/h value (heating capacity), temperature rise in °F (difference between supply and return air temperatures). Both values must be positive numbers for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the 1.08 constant in the formula?
A: The constant 1.08 is derived from: 0.24 (specific heat of air) × 0.075 (air density) × 60 (minutes/hour) = 1.08 BTU·min/(ft³·°F·hr)

Q2: What is a typical temperature rise for heating systems?
A: Typical temperature rises range from 30°F to 70°F for residential furnaces, with 40-50°F being common for forced-air systems.

Q3: Can this formula be used for cooling calculations?
A: Yes, the same formula applies for cooling, but with temperature drop instead of rise. The constant remains the same for standard air conditions.

Q4: How does altitude affect the calculation?
A: At higher altitudes, air density decreases, requiring adjustment of the constant. The formula assumes sea level conditions with standard air density.

Q5: What are typical CFM requirements for residential systems?
A: Residential systems typically require 400-2000 CFM depending on home size, with approximately 1 CFM per square foot of living space as a rough guideline.