Heat pumps · Error codes · Thermia
brine-outThermia · Diplomat
brine-out on a Thermia Diplomat: Brine out is less than the set minimum temperature. Compressor stopped. No hot water production
Short answer
On a Thermia heat pump, brine-out means: Brine out is less than the set minimum temperature. Compressor stopped. No hot water production. 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 out is less than the set minimum temperature. Compressor stopped. No hot water production.
Part involved: brine out sensor.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: Yes, when condition clears (inferred).
What you can check
- Note the exact alarm text. Look at the brine expansion tank: the fluid level should be visible (user guide check). Do not refill or open the ground-loop circuit yourself - call the installer. Acknowledge once by setting operating mode OFF then back; 'Other alarm message: reset the alarm; if the alarm remains, contact a service technician' (VUGFD302 p.16).
What the engineer will check
- Check brine-out sensor and ALARM BRINE setting; assess collector. Causes per the equivalent Danfoss service instructions VMGFC302 (same Danfoss-era controller) - not stated in the Thermia user manual.
Who to ask for: heat pump engineer.
What you might notice
Sources
- User manual Atria, Atria Duo, Atria Duo Optimum, Atria Optimum, Comfort, Diplomat, Diplomat Duo, Diplomat Duo Optimum (G2), Diplomat Optimum (G2) - 086U6297 Rev. 6 EN ↗ · 086U6297 Rev. 6 · page printed p.41 (PDF p.43) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026