Calculation sequence
Step-by-step method
- Confirm the fluid-property factor and temperature-difference sign convention.
- Multiply flow by the entered factor and temperature difference.
- Convert Btu/h to refrigeration tons in I-P mode.
MechanicalBeginnerHeat Transfer
Chilled-Water Tonnage Calculator
Calculate chilled-water load from flow, temperature difference, and a user-entered fluid factor.
Why it matters: Field tonnage is a direct commissioning screen for plant and coil performance.
Calculated result
Engineering evaluation
Calculated chilled-water capacity (Qc)208.3 ton
- Entered water flow (Qw)
- 500 gpm
- Entered temperature difference (ΔT)
- 10 °F
- Entered fluid factor (F)
- 500 Btu/(h·gpm·°F)
Engineering interpretation
The entered chilled-water condition represents approximately 208.3 ton.
Important limitations
- Use measured density and specific heat for glycol or unusual temperature. Flow and temperature readings should be simultaneous and uncertainty evaluated.
Engineering knowledge center
Understand the calculation—not just the answer
Governing relationships
Qc = Qw·F·ΔT/12000
Current substitution
Qc = 500×500×10/12000 = 208.3 ton.
Equation legend
Inputs and calculated quantities
- Qw
- Chilled-water flow — gpm or L/s
- ΔT
- Water temperature difference — °F or K
- F
- Entered fluid heat-transfer factor — Btu/(h·gpm·°F) or kW/(L/s·K)
- Qc
- Calculated chilled-water capacity — ton
- Qw
- Entered water flow — gpm
- ΔT
- Entered temperature difference — °F
- F
- Entered fluid factor — Btu/(h·gpm·°F)
Applications
How this calculation is used
Building design
Relate design water flow and temperature difference to cooling capacity.
Construction
Check scheduled flow and temperature conditions.
Commissioning
Calculate field cooling load while retaining the project-specific fluid factor.
Quality controls
Assumptions and limitations
Assumptions
- Entered values represent one stable operating condition and use consistent measurement boundaries.
- Fluid and air properties are representative of the evaluated condition.
Limitations
- This is a preliminary evaluation and field-verification tool, not a final sizing or code-compliance determination.
- Manufacturer data, adopted codes, project criteria, and professional engineering review remain controlling.
Field use
Verification procedure
- Confirm measurement boundaries, operating mode, and instrument calibration.
- Stabilize the system and record simultaneous readings.
- Compare the calculation with project requirements and manufacturer data before disposition.
Common engineering mistakes
- Mixing values from different operating conditions.
- Using nominal rather than measured flow, temperature, power, or fluid properties.
Technical basis
References and source standards
- ASHRAE Handbook—FundamentalsPsychrometrics, heat transfer, load relationships, and HVAC calculation context; verify the licensed current edition during professional review.
- U.S. Department of Energy—Better Buildings Solution CenterFederal energy-performance and HVAC equipment guidance; project and manufacturer data remain controlling.
- NIST Guide for the Use of the International System of UnitsFederal unit-system and conversion reference used for SI/I-P presentation.
Engineering calculation disclaimer
These engineering tools are provided for educational, preliminary evaluation, field verification, and commissioning support. Results depend on the accuracy of user-entered information and the assumptions stated for each calculation. Every colored status and comparison is a screening indicator only; project criteria, contract requirements, applicable codes, manufacturer instructions, measurement uncertainty, and authorized engineering judgment govern. The tools do not replace project-specific engineering analysis or the judgment of a licensed professional engineer.
Read the full use and limitation statement