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Rispri LabsENGINEERING A CIRCULAR FUTURE

Free tool · Water and wastewater treatment design

Water Chiller Tonnage Calculator

Cooling load (kW) = mass flow (kg/s) × specific heat (4.186 kJ/kg·°C) × temperature drop. Divide by 3.517 for tons of refrigeration (TR). Cooling 10 m³/h of water by 5 °C needs 58 kW, or 16.5 TR, before adding a safety margin.

Your inputs

Results update as you type. Example values are filled in.

°C
°C
%

How to use this calculator

  1. Enter the water flow through the process.
  2. Enter the warm return and chilled supply temperatures.
  3. Pick water or glycol and add a safety margin.
  4. Read the chiller size in TR and kW.

How do you calculate chiller tonnage?

Q (kW) = ṁ (kg/s) × cp (kJ/kg·°C) × ΔT (°C)

TR = kW ÷ 3.517

1 TR removes 12,000 BTU or 3,024 kcal per hour. A quick rule: TR = m³/h × ΔT ÷ 3.024 for water.

Worked example

With water flow 10 m³/h, return (warm) temperature 15 °C, supply (chilled) temperature 10 °C, fluid: Water (cp 4.186), safety margin 20 %, chiller type: Air cooled (about 1.1 kW/TR):

Recommended chiller size: 19.8 TR

The calculator also gives cooling load 16.5 TR; cooling load 58.1 kW; cooling load 49,999 kcal/h.

Assumptions and limits

  • Heat load is from the water circuit only; add pump heat and pipe gains if large.
  • Power figures are typical full load values; check the chiller data sheet.

Frequently asked questions

How many TR is needed for 1 m³/h of water?

One m³/h of water cooled by 1 °C needs 1.163 kW, or 0.33 TR. Multiply by your temperature drop.

What is 1 ton of refrigeration in kW?

One TR equals 3.517 kW of cooling, or 12,000 BTU/h.

Why add a safety margin?

Chiller capacity falls on hot days and as condensers foul. A 10 to 20% margin keeps the process at temperature.

References

  • ASHRAE Handbook, Fundamentals
  • BEE, Energy Performance Assessment of HVAC Systems

Built and maintained by the Rispri Labs engineering team. Last updated .