F8 on a Dimplex WPM heat pump manager platform: ODU extension: refrigeration circuit controller not detected
Short answer
On a Dimplex heat pump, F8 means: ODU extension: refrigeration circuit controller not detected. 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: ODU extension: refrigeration circuit controller not detected.
Part involved: Outdoor unit (ODU) refrigeration circuit controller / comms.
Likely causes:
- Connecting line interrupted/plug loose/lines mixed up.
- No power supply to outdoor controller.
- Outdoor unit switched off or breaker tripped (GDHV).
- Cable damage e.g. rodents or digging (GDHV).
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: After rectifying the fault the heat pump can be restarted; switching off the control voltage also acknowledges the fault (WPM Touch p.54). On text-display WPMs press Esc to acknowledge (EconPlus EN-16).
Manual reset: Acknowledge after rectification.
What you can check
- Check the outdoor unit's isolator switch next to the heat pump is ON.
- Check the consumer unit - if a heat pump breaker has tripped, reset it once; if it trips again leave it off and call an engineer.
- Look (without touching) for obvious external cable damage e.g. from rodents or digging.
- Note the fault code, the heat pump model (type plate) and controller software version shown in operating data, and contact the installer/Dimplex service.
What the engineer will check
- Check connecting line to extension/module: line interrupted, plug loose, individual lines mixed up.
- Check power supply to the module.
- Check bus/comms cable continuity between indoor WPM and outdoor controller.
Who to ask for: heat pump controls / electrical.
Certification: Electrical competence (Part P / qualified electrician) for work inside control panels.
What you might notice
Sources
- Dimplex WPM Touch heat pump manager - Operating instructions for users and specialists (Order no. 452117.66.02-EN, WPM3.13 / Display 1.15) ↗ · 452117.66.02-EN FD 0302 · page 54 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026