Heat pumps · Error codes · Stiebel Eltron
8185Stiebel Eltron · WPM 3 heat pump manager (older controller)
8185 on a Stiebel Eltron WPM 3 heat pump manager: Multiple occurrence of fault DEFROST or MIN FLOW COOL
Short answer
On a Stiebel Eltron heat pump, 8185 means: Multiple occurrence of fault DEFROST or MIN FLOW COOL. 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: Multiple occurrence of fault DEFROST or MIN FLOW COOL.
Part involved: water flow / pump / booster heater.
When it shows: Multiple occurrence of fault DEFROST or MIN FLOW COOL.
Likely causes:
- Check system temperatures/flow rate.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: no.
Manual reset: yes - WPM/IWS reset after cause removed (contractor).
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.
- Check the heating system pressure gauge reading is in the normal range stated by your installer.
- Check the outdoor unit air intake/discharge is not blocked by leaves, snow or ice (air source units).
What the engineer will check
- Check system temperatures/flow rate.
Who to ask for: Heating / heat pump engineer.
What you might notice
Sources
- OPERATION AND INSTALLATION Heat pump manager WPM 3 (DM0000035521) ↗ · A 316199-43934-9674 · page 52 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026