The-heat-pump-is-now-working-in-anti-freeze-mode on a Worcester Bosch Greenstore LECP ground source heat pump: The heat pump is now working in anti-freeze mode
Short answer
On a Worcester Bosch heat pump, The-heat-pump-is-now-working-in-anti-freeze-mode means: The heat pump is now working in anti-freeze mode. The heat pump keeps running. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: The heat pump is now working in anti-freeze mode.
Part involved: circuit flow temperature.
When it shows: Circuit flow temperature below 8 C and 10-min timer elapsed; resets above 25 C.
Likely causes:
- Circuit flow temperature below 8 C and 10-min timer elapsed; resets above 25 C.
Is it safe?
| Does the heat pump stop? | No |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running.
Resetting itself: yes.
Manual reset: Automatic.
What you can check
- Read and note the full alarm text and category letter shown on the controller and pass it to your installer.
What the engineer will check
- Diagnose per chapter 21: Circuit flow temperature below 8 C and 10-min timer elapsed; resets above 25 C.
Who to ask for: heat pump installer / heating engineer.
Certification: None specific for hydraulic checks; MCS-certified installer recommended for system changes.
What you might notice
Sources
- Installation, Commissioning and Servicing Instructions Worcester Greenstore LECP GSHP (System/Combi 6-11 kW) ↗ · 6 720 806 768 (2013/02) · page 62-63 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026