Chiller Sizing Calculator

Estimated Chiller Power is calculated as Required Cooling Capacity multiplied by a fixed 0.8 kW/ton assumption for a mid-efficiency water-cooled chiller, so dividing chiller power back by cooling tons always returns that same 0.8 figure — it cancels out algebraically. This output restates the calculator's built-in efficiency assumption rather than computing a value that responds to your inputs; real chillers range roughly 0.6-1.2 kW/ton depending on type and efficiency tier.

Required Cooling Capacity comes from the standard tonnage formula: Chilled Water Flow (GPM) times the temperature drop between Entering and Leaving Water Temp, divided by 24, then adjusted by Diversity Factor and Safety Factor. A bigger flow rate or a bigger temperature drop both raise the raw tonnage figure directly and proportionally.

Diversity Factor scales the load DOWN to reflect that not all connected load runs simultaneously — a typical value is 85%, meaning only 85% of the theoretical peak load is expected at once. Safety Factor then scales the result back UP as an oversizing margin, typically 110% (10% extra), to cover future expansion or unusually extreme conditions. They work in opposite directions on the same base tonnage figure.

Required Cooling Capacity depends on the temperature difference between Entering and Leaving Water Temp — a wider gap means each gallon of water is absorbing more heat as it passes through the building, which the chiller then has to remove. Raising Entering Water Temp while holding Leaving Water Temp fixed widens that gap and increases the calculated tonnage proportionally.