178 on a NIBE heat pump: Com. error pool: Communication with pool accessory card temporarily missing [other NIBE documents: Communication fault to accessory board / 3 communication errors in succession on the pool accessory card]
Short answer
On a NIBE heat pump, 178 means: Com. error pool: Communication with pool accessory card temporarily missing [other NIBE documents: Communication fault to accessory board / 3 communication errors in succession on the pool accessory card]. The heat pump keeps running with some functions stopped.
Reviewed 23 September 2026 · 1 source
What it means
The manuals for this range word it in different ways:
- Com. error pool: Communication with pool accessory card temporarily missing [other NIBE documents: Communication fault to accessory board / 3 communication errors in succession on the pool accessory card].
- High condensation water level: Alarm from external level monitor.
Part involved: PCB / accessory board communication; fans, air filters, air sensors.
When it shows: Communication with pool accessory card temporarily missing; Communication fault to accessory board; 3 communication errors in succession on the pool accessory card Alarm from external level monitor.
Likely causes:
- Defective communication cables; accessory activated in display but not connected; incorrectly connected communication cable; incorrectly set DIP switch; no electrical supply to accessory board; Check communication cables and DIP switch.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
The heat pump keeps running with some functions stopped.
Resetting itself: yes - Accessory 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 breakers for the heat pump, indoor module and any accessories are on at the consumer unit.
- 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 exhaust air valves/grilles in the rooms are open and not blocked; check the filter reminder in the user manual maintenance section.
What the engineer will check
- 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. NIBE lists: Defective communication cables; accessory activated in display but not connected; incorrectly connected communication cable; incorrectly set DIP switch; no electrical supply to accessory board; Check communication cables and DIP switch.
- Check ventilation airflow, fans, filters, air sensors and condensate drainage/level monitor.
Who to ask for: NIBE-trained heat pump installer (NIBE PRO / VIP).
Certification: Electrical work to BS 7671 by a competent person; None specific beyond competent heat pump installer; electrical work to BS 7671.
What you might notice
Sources
- TECHNICAL INFORMATION - ALARM LIST SMO 40 (TIF EN 2042-1, M12658EN) ↗ · TIF EN 2042-1 M12658EN · page 15 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026