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Ideal Logic System IE Gen 2 fault F0U

Flow/return differential greater than 50°C

Gas boiler

What it means

Fault indicating the temperature differential between flow and return exceeds 50°C, requires diagnostic procedure in Section 4.14.

Likely causes

  1. Isolation valves closed
  2. Pump not operating (wiring fault or pump failure)
  3. Radiator valves closed
  4. System blockage restricting flow

Where to start

  1. Check if isolation valves are open
  2. Check if pump is operating
  3. Check pump wiring if pump not operating

The full answer, free

  • 2 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 49), 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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