Author: Apex Engineering Sales | Last updated: July 15, 2026
Quick Answer
A common preliminary water-side heat load formula is Q = m × Cp × ΔT. For water, engineers often estimate heat load from flow rate and the difference between hot and cold water temperatures before final tower selection.
Basic Heat Load Formula
| Item | Why it matters | Practical note |
|---|---|---|
| Q | Heat load | kW or kcal/h |
| m | Mass flow rate | kg/s |
| Cp | Specific heat of water | Approx. 4.186 kJ/kg·°C for water |
| ΔT | Hot water temperature minus cold water temperature | °C |
| Wet-bulb temperature | Climate design limit | °C |
Data Required Before Calculation
- Confirm water flow unit.
- Confirm hot and cold water temperatures.
- Calculate temperature range.
- Check design wet-bulb temperature.
- Apply safety and project factors only after engineering review.
Useful Formula
Preliminary heat load: Q = m × Cp × ΔT. This is only an early screening formula; final equipment selection should follow engineering review.
Example Calculation Structure
- Mixing metric and imperial units.
- Using dry-bulb temperature instead of wet-bulb temperature.
- Treating a preliminary formula as final equipment selection.
Related Apex Cooling Tower Pages
- Cooling Tower Products
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- Request a Quote
- Contact Us
FAQ
What is the basic cooling tower heat load formula?
A simplified water-side formula is Q = m × Cp × ΔT, where ΔT is the cooling range between hot and cold water.
Can I select a tower only from this formula?
No. The formula is useful for early screening, but tower selection also depends on wet-bulb temperature, airflow, tower type, materials and site conditions.
What data should I send for a quote?
Send flow rate, hot and cold water temperatures, wet-bulb temperature, altitude, power supply, water quality, material preference and site limits.
Related Articles
Next step: If you already have project data, send your RFQ here and include flow, hot/cold water temperatures, design wet-bulb temperature, site altitude, power supply, noise target, water quality and material preference.