Riello NXHM fault E3

Final outlet water temp. sensor (T1) fault

Heat pump

What it means

Fault with the final outlet water temperature sensor T1.

Likely causes

  1. Sensor resistance out of range
  2. T1 sensor connector loosened
  3. T1 sensor connector wet or has water ingress
  4. T1 sensor failure

Where to start

  1. Check the resistance of the sensor
  2. Check if T1 sensor connector is loosened
  3. Check if connector is wet or has water in it

The full answer, free

  • How to put it right, step by step
  • The manual page for this fault (page 64), right under the answer

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