| Parameter | Limit |
|---|---|
| HW heater outlet | ≥ 140°F (60°C) |
| Distal hot fixture | ≥ 122°F (50°C) |
| Recirc return | ≥ 124°F |
| Cold water supply | ≤ 68°F (20°C) |
| Free Cl₂ at distal | ≥ 0.2 ppm |
| Legionella growth zone | 68°F – 122°F |
| Cooling tower ORP | ≥ 650 mV |
| Pool / spa Cl₂ | ≥ 3.0 ppm |
| Cooling tower Cl₂ | 1.0 – 3.0 ppm |