212 on a NIBE heat pump: Cmpr has not been running for 1 week: Compressor has not been in operation for one week
Short answer
On a NIBE heat pump, 212 means: Cmpr has not been running for 1 week: Compressor has not been in operation for one week. The manual does not say whether the heat pump stops. 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:
- Cmpr has not been running for 1 week: Compressor has not been in operation for one week.
- Low pressure alarm, cooling operation: 5 repeated alarms for low low-pressure within 4 hours [other NIBE documents: Low low-pressure in cooling operation].
Part involved: heating medium flow, charge pump, particle filter; pressure switches/sensors, expansion valve.
When it shows: Compressor has not been in operation for one week 5 repeated alarms for low low-pressure within 4 hours; Low low-pressure in cooling operation.
Likely causes:
- Check settings.
- S2125: Poor flow; significant wind effect | F2120: Poor flow; significant wind effect.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: no/unknown - According to selected measure in menu.
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. Read the heating system pressure gauge and check that radiator/underfloor thermostats are not all closed; check heating and hot water temperature settings have not been changed.
- 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 heating medium flow (pump speed/settings, particle filter, air in system), heating curve and hot water settings, correct sensor placement and flow/return connections. NIBE lists: Check settings.
- 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: Poor flow; significant wind effect.
Who to ask for: NIBE-trained heat pump installer (NIBE PRO / VIP); Heat pump engineer with F-gas qualification (NIBE-trained / NIBE PRO installer).
Certification: None specific beyond competent heat pump installer; electrical work to BS 7671; 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 4 · Reviewed 23 September 2026
- Installer manual Air/water heat pump NIBE S2125 UK 1x230V IHB EN 2525-1 (831874) ↗ · IHB EN 2525-1 · page 41 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026