8291 on a Stiebel Eltron WPM 3 heat pump manager: Low relevance communication objects have been incorrectly transferred repeatedly between the IWS and inverter (fan section)
Short answer
On a Stiebel Eltron heat pump, 8291 means: Low relevance communication objects have been incorrectly transferred repeatedly between the IWS and inverter (fan section). The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Low relevance communication objects have been incorrectly transferred repeatedly between the IWS and inverter (fan section).
Part involved: compressor/fan inverter.
When it shows: Low relevance communication objects have been incorrectly transferred repeatedly between the IWS and inverter (fan section).
Likely causes:
- Inverter fault. Check wiring and associated plug-in connectors; replace if faulty. Test inverter power supply.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: yes - restarts after idle time.
Manual reset: after 5 faults in 2 h run: IWS reset.
What you can check
- Read and note the full message code and time from the WPM display (DIAGNOSIS / NOTIFICATIONLIST if accessible without a code).
- Check the heat pump and controller circuit breakers/isolators at the consumer unit are on.
What the engineer will check
- Inverter fault. Check wiring and associated plug-in connectors; replace if faulty. Test inverter power supply.
Who to ask for: Heat pump service engineer (electrical/controls).
Certification: Qualified electrician competence for live-work on appliance electrics.
What you might notice
Sources
- OPERATION AND INSTALLATION Heat pump manager WPM 3 (DM0000035521) ↗ · A 316199-43934-9674 · page 49 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026