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Riello NXHM fault E5

Condenser outlet refrigerant temperature sensor (T3) error

Heat pump

What it means

Fault with the condenser outlet refrigerant temperature sensor T3.

Likely causes

  1. T3 sensor connector loosened
  2. T3 sensor connector wet or has water ingress
  3. T3 sensor failure
  4. Rapid temperature change during initial heating of underfloor heating screed

Where to start

  1. Check if T3 sensor connector is loosened
  2. Check if connector is wet or has water in it
  3. Calculate tonnes of CO2 equivalent of refrigerant charge in unit

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 66), right under the answer
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Safety: Isolate the heat pump and any backup heater, and give the inverter capacitors time to discharge before you open the electrics. Anything on the refrigerant circuit needs F-gas certification.

From the Riello manual for the NXHM. Check the model on the data plate before you order parts.

Other Riello NXHM fault codes