HP ALARM Stulz — High Head Pressure Alarm
At a glance
- Severity
- FAULT STOP
- Domain
- PRECISION_COOLING_SYSTEM
- Reference standard
- EN 378 / F-Gas EU 517/2014
What it means
Condensing pressure exceeds the limit and the CRAC compressor stops: the room is no longer cooled.
Probable causes
- Dirty condenser coil (dust, fibres, salt)
- Condenser fans failed or running slow
- Refrigerant overcharge or non-condensables in the circuit
- Outdoor temperature above design conditions
- Head pressure control (modulating fans) out of calibration
Where to start
Measure condensing pressure and subcooling against the P/T chart of the refrigerant at the current outdoor temperature.
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
- HUMIDITY ALARM — Humidity Control Fault
- LP ALARM — Low Suction Pressure Alarm