F21 on a Dimplex WPM heat pump manager platform: Brine pressure monitoring: the brine pressure monitor in the brine circuit has tripped
Short answer
On a Dimplex heat pump, F21 means: Brine pressure monitoring: the brine pressure monitor in the brine circuit has tripped. 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: Brine pressure monitoring: the brine pressure monitor in the brine circuit has tripped.
Part involved: Brine pressure monitor.
Likely causes:
- Brine pressure too low.
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
- 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 the brine pressure.
- Leak-check brine circuit.
Who to ask for: ground source / 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