224 on a NIBE heat pump: Fan alarm: Heat pump (outdoor unit) sends fan fault message to the controller [other NIBE documents: Deviations in fan speed in the outdoor unit / Deviations in the fan speed in F2120]
Short answer
On a NIBE heat pump, 224 means: Fan alarm: Heat pump (outdoor unit) sends fan fault message to the controller [other NIBE documents: Deviations in fan speed in the outdoor unit / Deviations in the fan speed in F2120]. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manuals for this range word it in different ways:
- Fan alarm: Heat pump (outdoor unit) sends fan fault message to the controller [other NIBE documents: Deviations in fan speed in the outdoor unit / Deviations in the fan speed in F2120].
- Perm. com. error HW-comfort: No communication with accessory card for 15 s.
Part involved: fan motor; PCB / accessory board communication.
When it shows: Heat pump (outdoor unit) sends fan fault message to the controller; Deviations in fan speed in the outdoor unit; Deviations in the fan speed in F2120; 5 unsuccessful start attempts; No feedback signal from the fan 5 times within 240 minutes; Deviations in the fan speed in F2050; Deviations in the fan speed in F2040 No communication with accessory card for 15 s.
Likely causes:
- F2120: The fan cannot spin freely or is not connected | F2120: Fan blocked or not connected; significant wind effect | S2125: Fan blocked or not connected; significant wind effect | S2060: Fan blocked or not connected; defective or dirty baseboard AA2; defective fan motor; tripped fuse F2 | F2050: Fan cannot rotate freely; defective PWB1; defective fan motor; PWB1 dirty; fuse F2 tripped | F2040: Fan cannot rotate freely; defective control board; defective fan motor; control board dirty; fuse F2 blown.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| 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. Check the outdoor unit is not blocked by leaves, snow, ice or stored items and air can flow freely.
- 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. Check the breakers for the heat pump, indoor module and any accessories are on at the consumer unit.
What the engineer will check
- Check fan rotates freely, fan motor, fan connections, fuse and control board in the outdoor unit. NIBE lists: Fan blocked or not connected; defective fan motor; fuse blown; The fan cannot spin freely or is not connected; Fan blocked or not connected; significant wind effect; Fan blocked or not connected; defective or dirty baseboard AA2; defective fan motor; tripped fuse F2; Fan cannot rotate freely; defective PWB1; defective fan motor; PWB1 dirty; fuse F2 tripped; Fan cannot rotate freely; defective control board; defective fan motor; control board dirty; fuse F2 blown.
- Check communication cables and connectors between PCBs/accessory boards, DIP-switch addressing, power supply to the accessory board, and that accessories activated in the menu are actually fitted.
Who to ask for: NIBE-trained heat pump installer (NIBE PRO / VIP).
Certification: Electrical work to BS 7671 by a competent person.
What you might notice
Sources
- TECHNICAL INFORMATION - ALARM LIST SMO 40 (TIF EN 2042-1, M12658EN) ↗ · TIF EN 2042-1 M12658EN · page 5 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026