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Ventilation Products  Library Sales Service Store
 
Cooling Formulas
 
CONVERSION
1 Ton = 12000 Btu/hr

 
COOLING LOAD REQUIREMENT
Total Cooling Load (Btu/hr) = 4.5 x CFM x (H1 – H2)
 
Where:
CFM = Airflow in Cubic Feet Per Minute
H1 = Entering Air Enthalpy (Btu/lbm dry air)
H2 = Leaving Air Enthalpy (Btu/lbm dry air)
 
Or
 
Total Cooling Load (Btu/hr) = Sensible Cooling Load (Btu/hr) + Latent Cooling Load (Btu/hr)
 
Where:
Sensible Cooling Load (Btu/hr) = CFM x Density Factor x (T1 – T2)
Latent Cooling Load (Btu/hr) = CFM x 0.69143 x (G1 – G2)
 
Where:
CFM = Airflow in Cubic Feet Per Minute
Density Factor =   1.08 +  (70-Blower Temp) * .024

10
T1 = Entering Air Drybulb Temperature (°F)
T2 = Leaving Air Drybulb Temperature (°F)
G1 = Grains of Moisture of Entering Air = 7000 x humidity ratio (lbm moisture/lbm of dry air)
G2 = Grains of Moisture of Leaving Air = 7000 x humidity ratio (lbm moisture/lbm of dry air)

 
EFFICIENCY CALCULATION
SEER = BTU / W-hr

 
COST OF COOLING:
Cost of cooling = BTU/hr x hrs of operation x electricity cost ($/kw-hr) / (SEER x 1000)