Every floor tells a different story.

Distributed chlorine sensing reveals what a mixed return can hide.
━ Cold circulation┄ Domestic hot waterIllustrative day · 00:00
Combined cold return
Combined hot return
Floor 4 · Persistent low cold and hot-water residual · Suspected biofouling
Simulated 24-hour history: Floor 4 hot return (amber), mixed hot return (pale blue) · chlorine, mg/L
Illustrative readings, not operating limits or field data. Separate hot and cold circuits; returns mix only within the same circuit. Equal floor-return flows assumed. Cold circulation represents an engineered recirculating system. Low residual warrants investigation; it does not establish biofouling.