E1X.T1-high on a Worcester Bosch Greenstore LECP ground source heat pump: High flow temperature E1X.T1
Short answer
On a Worcester Bosch heat pump, E1X.T1-high means: High flow temperature E1X.T1. 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: High flow temperature E1X.T1.
Part involved: T1 flow.
When it shows: Flow 5 K above highest set point for circuit (factory 60 C radiators / 35 C UFH); compressor stops.
Likely causes:
- Flow 5 K above highest set point for circuit (factory 60 C radiators / 35 C UFH); compressor stops.
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.
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.
- Check the heating system pressure gauge reading (Bosch guidance is typically 1-2 bar when cold); report low pressure to your installer.
What the engineer will check
- Diagnose per chapter 21: Flow 5 K above highest set point for circuit (factory 60 C radiators / 35 C UFH); compressor stops.
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 60 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026