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Ideal Logic System IE Gen 2 fault L01

Flow temperature overheat lockout

Gas boiler

What it means

Boiler has locked out due to flow temperature overheat condition.

Likely causes

  1. System not filled/vented
  2. Closed valves
  3. Excessive flow/return differential
  4. Pump not rotating freely / pump failure
  5. System not filled with water
  6. Isolation, system filter or radiator valves closed
  7. Flow/Return differential in excess of 30°C
  8. Isolation valves closed
  9. Pump not operating
  10. System blockages
  11. Pump not operating (wiring fault or pump failure)
  12. System blockage restricting flow
  13. Thermistor fault requiring replacement
  14. Faulty or failed return thermistor requiring replacement

Where to start

  1. Verify boiler and CH system filled with water
  2. Verify all isolation, system filter and radiator valves are open
  3. Measure flow/return differential across boiler

The full answer, free

  • 38 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 50), right under the answer
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Safety: Isolate gas and power before you open the case. If you have been into the gas side, do a tightness test, and a combustion and flue check before you hand back. Gas Safe (UK) or RGI (Ireland) work only.

From the Ideal manual for the Logic System IE Gen 2. Check the model on the data plate before you order parts.

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