HUMIDITY ALARM Stulz — Humidity Control Fault
At a glance
- Severity
- WARNING
- Domain
- PRECISION_COOLING_SYSTEM
- Reference standard
- ASHRAE TC9.9 / EN 50600-3-1
What it means
Relative humidity leaves the control band (typically 40-60%) due to humidifier failure, sensor drift or a blocked drain.
Probable causes
- Electrode cylinder humidifier exhausted or scaled
- Demineralized water exhausted or feed valve closed
- RH sensor out of calibration or drifted
- Humidifier drain clogged
- Control band too narrow between neighbouring units (hunting)
Where to start
Inspect the humidifier group: electrode cylinder, water feed, drain, level and valve.
Full guided diagnosis in the app
The diagnostic tree for this fault has 5 guided steps with measurements, checks and resolutions. You'll find it in DataCIQ, one of the five IndexOS apps: free, works offline.
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The same fault on other brands
More Stulz codes
- CONDENSATE ALARM — Water Leak / Condensate Overflow
- FILTER ALARM — Low Airflow / High Filter ΔP
- HP ALARM — High Head Pressure Alarm
- LP ALARM — Low Suction Pressure Alarm