How to Determine Chiller Size Needed

1 Calculate Temperature Differential (ΔT°F)

ΔT°F = Incoming Water Temperature (°F) - Required Chilled Water Temperature

Example: 85°F - 75°F = 10°F

2 Calculate BTU/hr

BTU/hr = Gallons per hr x 8.33 x ΔT°F

Example: (4 gpm x 60) x 8.33 x 10°F = 19,992 BTU/hr

3 Calculate Tons of Cooling Capacity

Tons = BTU/hr ÷ 12,000

Example: 19,992 BTU/hr ÷ 12,000 = 1.666 tons

4 Oversize the Chiller by 20% and Round Up

Ideal Size in Tons = Tons x 1.2

Example: 1.666 tons x 1.2 = 1.9992 tons ; a 2 ton chiller is needed