M = E + B + D = 15 + 3.75 + 0.1 = 18.85 gpm Rule of thumb: Make-up ≈ 1.5–2.5% of circulation rate for most HVAC towers; higher for industrial (more blowdown). 4. Water Quality Requirements Poor make-up water causes scaling, corrosion, or biological growth.
3. How to Calculate Make-Up Water Flow Step 1 – Evaporation (E) E (gpm) = Recirculation Rate (gpm) × Cooling Range (°F) × 0.001 Example: 1000 gpm system, 15°F range → E = 1000 × 15 × 0.001 = 15 gpm
1. What is Make-Up Water? Make-up water is fresh water added to a cooling tower system to compensate for total water losses. Without it, the system would run dry, lose efficiency, and suffer severe damage. 2. Why is Make-Up Water Needed? Water leaves a cooling tower system in three primary ways: