HVAC Information
Heat Load Calculation
Formula: Q = Area (sq.ft) x Heat Load Factor (BTU/hr per sq.ft)
Example: 500 sq.ft office: Q = 500 x 30 = 15,000 BTU/hr TR = 1.25
CFM Calculation
Formula: CFM = Sensible Heat (BTU/hr) / (1.08 x Delta T)
Example: 12,000 BTU/hr, Delta T = 20¡ãF CFM = 556 ¡ú
AHU / FCU Sizing
Rule: 1 TR = 400 CFM
Duct Sizing Heat Load Calculat
Velocity Limits:
Main: 1400-1800 FPM
800 CFM @ 1000 FPM 0.8 sq.ft 14"x10"
Chilled Water Flow Rate
Formula: GPM = BTU/hr/ (500 x Delta T)
Example: 24,000 BTU/hr GPM = 4.8
Pipe Sizing
Chiller Sizing
Formula: TR = BTU/hr / 12,000
Example: 60,000 BTU/hr 5 TR
Cooling Tower Sizing
Rule:
Heat Rejection = 1.25 x Load
10 TR ¡ú Tower = 12.5 TR