TradeAssistIQHome

Riello NXHM fault PP

Tw_out - Tw_in unusual protection

Heat pump

What it means

Abnormal temperature difference protection between water outlet and inlet sensors.

Likely causes

  1. Sensor resistance abnormal
  2. Incorrect sensor locations
  3. Water inlet/outlet sensor wire connector loosened
  4. Four-way valve blocked
  5. Four-way valve broken

Where to start

  1. Check the resistance of the two sensors
  2. Check the two sensors locations
  3. Check if the water inlet/outlet sensor wire connector is loosened

The full answer, free

  • How to put it right, step by step
  • The manual page for this fault (page 65), right under the answer
Ask about PP freeCreate a free account

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