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Water System BTU Calculation
For hydronic heating, boilers, water heaters, and chilled water systems
About Water System BTU Calculations
Formula: BTU/hr = Flow Rate (GPM) × Temperature Difference (°F) × 500
The constant 500 combines water density (8.33 lb/gal), specific heat (1 BTU/lb-°F), and time conversion (60 min/hr).
Applications: Boiler sizing, hydronic heating design, chilled water systems, heat exchanger calculations, water heater capacity, radiant heating systems.
Air System BTU Calculation
For forced air heating, HVAC systems, and air handlers
About Air System BTU Calculations
Formula: BTU/hr = Air Flow (CFM) × Temperature Difference (°F) × 1.08
The constant 1.08 combines air density conversion (0.075 lb/ft³), specific heat of air (0.24 BTU/lb-°F), and time conversion (60 min/hr).
Note: This formula is accurate for dry air at approximately 70°F. Accuracy decreases significantly at temperatures much higher or lower than 70°F.
Applications: Furnace sizing, air handler capacity, duct design, HVAC load calculations, ventilation systems.
Understanding BTUs
A BTU (British Thermal Unit) is a standard unit of heat energy. One BTU is approximately the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit.
In HVAC and plumbing applications, BTU calculations help determine proper equipment sizing, system capacity, and energy requirements. Accurate BTU calculations ensure efficient operation and proper system performance.