E2X-T10T11-delta on a Worcester Bosch Greenstore LECP ground source heat pump: High temperature difference collector circuit E2X
Short answer
On a Worcester Bosch heat pump, E2X-T10T11-delta means: High temperature difference collector circuit E2X. 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: High temperature difference collector circuit E2X.
Part involved: T10/T11 delta (>6 K).
When it shows: Difference between T10 and T11 exceeds 6 K (measured 30 min after start; 15 min delay).
Likely causes:
- Difference between T10 and T11 exceeds 6 K (measured 30 min after start; 15 min delay).
Is it safe?
| Does the heat pump stop? | No |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running.
Resetting itself: no.
Manual reset: Deactivated on acknowledgement.
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: Difference between T10 and T11 exceeds 6 K (measured 30 min after start; 15 min delay).
Who to ask for: ground source heat pump engineer.
Certification: F-gas certification for refrigerant circuit; competent person for electrical work.
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 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026