F9 on a Dimplex WPM heat pump manager platform: Flow frost protection: the generator circuit pump M16 is switched on for frost protection and no flow is detected
Short answer
On a Dimplex heat pump, F9 means: Flow frost protection: the generator circuit pump M16 is switched on for frost protection and no flow is detected. 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 manual says: Flow frost protection: the generator circuit pump M16 is switched on for frost protection and no flow is detected.
Part involved: Generator circuit pump M16 / flow switch.
When it shows: M16 running for frost protection with no flow detected.
Likely causes:
- Insufficient heating water flow rate.
- Pump M16 faulty.
- No power supply to M16.
- Controller output for M16 faulty.
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: 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 heating system pressure gauge reads within the installer's stated range (typically 1.0-1.5 bar).
- 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 heating water flow rate.
- Check pump M16.
- Check power supply M16.
- Check controller outlet M16.
Who to ask for: heating engineer / hydraulics.
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