F25 on a Dimplex WPM heat pump manager platform: Low pressure: the heat source is producing insufficient energy
Short answer
On a Dimplex heat pump, F25 means: Low pressure: the heat source is producing insufficient energy. 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 pressure: the heat source is producing insufficient energy.
Part involved: Low-pressure switch/sensor.
Likely causes:
- Dirt trap filter blocked.
- Air in heat source system.
- Insufficient brine/water flow.
- Evaporator iced up or system temperatures too low (return < 18C).
- Obstructed air flow or cold-air recirculation from adjacent unit (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
- Air source: check nothing obstructs the fan/coil and clearances are free.
- Check another outdoor unit is not blowing cold air into this unit's intake (GDHV).
- 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
- Clean the dirt trap filter.
- Purge the heat source system.
- Check brine/water flow.
- Check refrigerant charge (F-Gas).
- Inform after-sales service.
Who to ask for: heat pump service engineer / refrigeration.
Certification: F-Gas (refrigerant handling) certification for any refrigerant-circuit work.
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