230 on a NIBE heat pump: Hot gas alarm: Heat pump (outdoor unit) sends hot gas fault message to the controller [other NIBE documents: Temperature deviations on discharge sensor (F2120: 3 times within 4 h; F2040/AMS: 2 times within 60 min or continuous 60 min) / High hot gas alarm 3 times in a row within 4 hours]
Short answer
On a NIBE heat pump, 230 means: Hot gas alarm: Heat pump (outdoor unit) sends hot gas fault message to the controller [other NIBE documents: Temperature deviations on discharge sensor (F2120: 3 times within 4 h; F2040/AMS: 2 times within 60 min or continuous 60 min) / High hot gas alarm 3 times in a row within 4 hours]. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 2 sources
What it means
The manuals for this range word it in different ways:
- Hot gas alarm: Heat pump (outdoor unit) sends hot gas fault message to the controller [other NIBE documents: Temperature deviations on discharge sensor (F2120: 3 times within 4 h; F2040/AMS: 2 times within 60 min or continuous 60 min) / High hot gas alarm 3 times in a row within 4 hours].
- Low pressure alarm: Low-pressure sensor BP8 (PSL) detects abnormally low pressure [other NIBE documents: Too low value on the low pressure sensor 3 times within 60 minutes / Heat pump (selected outdoor unit) sends fault message to controller].
Part involved: compressor discharge (hot gas); pressure switches/sensors, expansion valve.
When it shows: Heat pump (outdoor unit) sends hot gas fault message to the controller; Temperature deviations on discharge sensor (F2120: 3 times within 4 h; F2040/AMS: 2 times within 60 min or continuous 60 min); High hot gas alarm 3 times in a row within 4 hours; 3 repeated alarms for high discharge within 4 hours; High temperature on discharge sensor BT14, 2 times within 60 minutes or at 115 C or higher for 60 minutes; Temperature deviation on hot gas sensor (Tho-D) twice within 60 min or 60 min continuously Low-pressure sensor BP8 (PSL) detects abnormally low pressure; Too low value on the low pressure sensor 3 times within 60 minutes; Heat pump (selected outdoor unit) sends fault message to controller.
Likely causes:
- F2120: Sensor not working; insufficient air circulation or blocked heat exchanger; refrigerant leak; defective compressor; external wind effect | F2120: Disruption in the refrigerant circuit; lack of refrigerant | S2125: Disruption in the refrigerant circuit; lack of refrigerant | S2060: Disruption in refrigerant circuit; lack of refrigerant | F2050: Sensor not working; insufficient air circulation or blocked heat exchanger; in cooling possibly insufficient refrigerant; defective PWB1 | F2040: Sensor not working; insufficient air circulation or blocked heat exchanger; in cooling possibly insufficient refrigerant; defective control board.
- S2060: Open/short circuit on LP sensor input; defective LP sensor; defective baseboard AA2; open/short circuit or defective suction gas sensor BT17 (Tho-S); lack of refrigerant | F2050: Open/short circuit on LP sensor input; defective LP sensor; defective PWB1; open/short circuit or defective suction gas sensor Tho-S.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Safety lockout |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: no/unknown - Compressor blocked.
Manual reset: Reset from the controller alarm menu ('reset alarm' / 'Reset alarm and try again'); alarm recurs if the cause remains.
What you can check
- Read the alarm text and the 'info/action' help on the controller display (VVM/SMO or S-series smartguide). NIBE's manuals let the homeowner select 'reset alarm' ('Reset alarm and try again' on S-series); if the lamp returns to normal the alarm has cleared. If it comes back, do not keep resetting: select 'aid mode' ('Auxiliary operation' on S-series) if offered, so any electric additional heat keeps heat/hot water going, and contact your installer. Air source systems: check the outdoor unit is clear of leaves/snow/ice. Read the heating system pressure gauge and note the reading for your installer.
What the engineer will check
- Check discharge sensor BT14 mounting, refrigerant charge and circuit (F-gas qualified), airflow over evaporator and heating medium flow. NIBE lists: Disruption in refrigerant circuit; lack of refrigerant; Sensor not working; insufficient air circulation or blocked heat exchanger; refrigerant leak; defective compressor; external wind effect; Disruption in the refrigerant circuit; lack of refrigerant; Sensor not working; insufficient air circulation or blocked heat exchanger; in cooling possibly insufficient refrigerant; defective PWB1; Sensor not working; insufficient air circulation or blocked heat exchanger; in cooling possibly insufficient refrigerant; defective control board.
- Check heating medium flow, particle filter and circulation pump; check pressure switches/sensors, expansion valve, service valves and refrigerant charge (F-gas qualified). NIBE lists: Open/short circuit on LP sensor input; defective LP sensor; defective baseboard AA2; open/short circuit or defective suction gas sensor BT17 (Tho-S); lack of refrigerant; Open/short circuit on LP sensor input; defective LP sensor; defective PWB1; open/short circuit or defective suction gas sensor Tho-S.
Who to ask for: Heat pump engineer with F-gas qualification (NIBE-trained / NIBE PRO installer).
Certification: F-gas certification for refrigerant circuit work (plus flammable-refrigerant competence for R290/R32 models).
What you might notice
Sources
- TECHNICAL INFORMATION - ALARM LIST SMO 40 (TIF EN 2042-1, M12658EN) ↗ · TIF EN 2042-1 M12658EN · page 6 · Reviewed 23 September 2026
- Installer manual Air/water heat pump NIBE S2060 UK 1x230V IHB EN 2623-3 (831281) ↗ · IHB EN 2623-3 · page 30 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026