Author: Apex Engineering Sales | Last updated: July 15, 2026
Quick Answer
Cooling tower range is the difference between hot water temperature and cold water temperature. Cooling tower approach is the difference between cold water temperature and entering air wet-bulb temperature.
Definitions
| Item | Why it matters | Practical note |
|---|---|---|
| Hot water temperature | Water entering the tower | Example: 37°C |
| Cold water temperature | Water leaving the tower | Example: 32°C |
| Range | Hot water minus cold water | 37°C – 32°C = 5°C |
| Wet-bulb temperature | Ambient evaporative cooling reference | Example: 28°C |
| Approach | Cold water minus wet-bulb | 32°C – 28°C = 4°C |
Why Approach Matters
- Collect hot water temperature.
- Define required cold water temperature.
- Get design wet-bulb temperature.
- Calculate range and approach.
- Review whether the approach is realistic for the project.
Useful Formula
Preliminary heat load: Q = m × Cp × ΔT. This is only an early screening formula; final equipment selection should follow engineering review.
Simple Calculation Table
- Using dry-bulb temperature for approach.
- Requesting an unrealistically low cold-water temperature.
- Comparing towers without the same wet-bulb condition.
Related Apex Cooling Tower Pages
- Cooling Tower Products
- https://apextowerchina.com/request-a-quote/
- https://apextowerchina.com/contact/
- Request a Quote
- Contact Us
FAQ
What is cooling tower range?
Range is the temperature drop across the tower: hot water temperature minus cold water temperature.
What is cooling tower approach?
Approach is the cold water temperature minus the entering air wet-bulb temperature.
Is a smaller approach always better?
A smaller approach can require a larger tower and higher cost. It should be evaluated against project performance and lifecycle requirements.
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.