Chilled Water Cooling Coil Calculator

Calculate coil capacity, gpm, dew point, and moisture removal. Review air and water conditions clearly. Get dependable estimates for chilled water coil sizing today.

Calculator Form

Example Data Table

Airflow Entering Air Leaving Air Water In/Out Total Load Flow Condensate
5000 CFM 80°F / 55% RH 58°F / 92% RH 44°F / 54°F 177866.42 Btu/hr 35.57 gpm 6.74 gal/hr

Formula Used

This calculator uses moist air and chilled water balance equations. It estimates psychrometric properties from dry bulb temperature, relative humidity, and pressure.

Humidity Ratio: W = 0.621945 × Pv / (P − Pv)

Enthalpy: h = 0.24T + W(1061 + 0.444T)

Dry Air Mass Flow: m = 60 × CFM / specific volume

Total Load: Q = m × (h entering − h leaving)

Sensible Load: Qs = m × Cp × (T entering − T leaving)

Latent Load: Ql = Qt − Qs

Water Flow: GPM = Q / (500 × water delta T)

Condensate: m × (W entering − W leaving)

LMTD: uses the air and water end temperature differences for an approximate coil UA estimate.

How to Use This Calculator

  1. Enter the coil airflow in CFM.
  2. Input entering air dry bulb temperature and relative humidity.
  3. Input leaving air dry bulb temperature and relative humidity.
  4. Enter chilled water supply and return temperatures.
  5. Keep pressure at standard atmosphere unless your site differs.
  6. Press the calculate button.
  7. Review total load, sensible load, latent load, gpm, and condensate.
  8. Download the result as CSV or PDF if needed.

About Chilled Water Cooling Coil Calculations

Why this calculator matters

Chilled water cooling coils remove heat and moisture from moving air. That process affects comfort, indoor air quality, and plant efficiency. A quick estimate helps during design, review, and troubleshooting. This calculator combines airflow, water temperature, and psychrometric inputs in one place. It gives a practical output for capacity checks.

What the calculation includes

The tool evaluates both sensible and latent cooling. Sensible cooling lowers the air temperature. Latent cooling removes moisture. Together they define total coil load. The calculator also estimates dew point, humidity ratio, enthalpy, condensate rate, and required chilled water flow. These values help compare air-side and water-side performance.

How the chemistry link appears

Air and water exchange energy through phase change and heat transfer. Moisture condenses when the coil surface drops below the air dew point. That makes this problem strongly tied to physical chemistry. Vapor pressure, saturation, and water content all influence coil behavior. Even small humidity changes can shift capacity and condensate output.

How to read the results

Total load shows the overall cooling duty. Sensible load shows dry temperature reduction. Latent load shows moisture removal. The sensible heat ratio explains the split between them. Higher latent share often means more dehumidification. Required gpm helps confirm piping and valve sizing. Condensate helps with drain pan checks and maintenance planning.

Best use cases

Use this calculator for preliminary sizing, classroom work, HVAC audits, and quick engineering review. It also helps compare alternative leaving conditions. The built-in pressure field supports nonstandard sites. Results are estimates, not certified selections. Final coil selection should still use manufacturer software, project safety factors, and detailed psychrometric verification.

Frequently Asked Questions

1. What does this calculator estimate?

It estimates total coil load, sensible load, latent load, required chilled water flow, condensate rate, dew point, enthalpy, humidity ratio, and approximate UA.

2. Why do I need entering and leaving air humidity?

Humidity drives latent cooling. Without it, moisture removal and total enthalpy change cannot be estimated well.

3. Why is return water temperature higher than supply?

The coil absorbs heat from air. That heat raises the chilled water temperature before it leaves the coil.

4. What units does the calculator use?

It uses IP units. Airflow is in CFM. Temperatures are in °F. Pressure is in psia. Load is in Btu/hr. Water flow is in gpm.

5. Is the UA result exact?

No. It is an approximate value based on LMTD from air and water end temperatures. Use manufacturer data for final coil selection.

6. What if latent load shows zero?

That usually means the leaving humidity ratio is not lower than entering humidity ratio. The coil may be cooling mostly sensibly in that case.

7. Can I use this at high altitude?

Yes. Change the atmospheric pressure field. Lower pressure changes humidity ratio, enthalpy, and mass flow.

8. Is this suitable for final design approval?

It is best for fast estimation and review. Final approval should use detailed psychrometrics, coil software, and project-specific engineering checks.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.