Work out chiller tonnage instantly with clear inputs, formula shown and shareable results.
Water-side heat transfer is flow times temperature difference times 500, the constant that folds together water density, specific heat and minutes per hour for US gallons. Dividing by 12,000 gives tons. The classic design point of 2.4 GPM per ton corresponds to a 10 °F chilled water range.
Water side duty
BTU/h = GPM x ΔT x 500
Tonnage
tons = BTU/h x (1 + margin) / 12000; kW = tons x 3.517
BTU/h = GPM x ΔT x 500. Water-side heat transfer is flow times temperature difference times 500, the constant that folds together water density, specific heat and minutes per hour for US gallons.
A wider range moves the same duty with less water, cutting pump power sharply because pump power varies with the cube of flow.
This calculator takes 3 inputs: Chilled water flow, Water temperature difference, Sizing margin. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.