F31 on a Dimplex WPM heat pump manager platform: Flow: the heat pump has been switched off because there is no flow in the primary or secondary circuit
Short answer
On a Dimplex heat pump, F31 means: Flow: the heat pump has been switched off because there is no flow in the primary or secondary circuit. 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: Flow: the heat pump has been switched off because there is no flow in the primary or secondary circuit.
Part involved: Flow switch / flow sensor.
Likely causes:
- Insufficient water flow in the well or brine circuit.
- Insufficient water flow in the secondary circuit.
- Incorrect flow direction.
- Closed isolation valves, blocked strainer, air, M16 pump configuration, multiple-heat-pump hydraulics (GDHV).
- Rarely faulty flow switch/sensor (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 heating system pressure gauge reads 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 flow rate vs nominal.
- Check strainer/mag filter.
- Check isolation valves.
- Check M16 pump configuration.
- Check flow switch/sensor.
Who to ask for: heating engineer.
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 55 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026