Riello NXHM fault P4
High discharge temperature protection
Heat pumpWhat it means
Compressor discharge temperature has exceeded safe limits.
Likely causes
- Same reason as P1
- TW_out temp sensor is loosen
- T1 temp sensor is loosen
- T5 temp sensor is loosen
Where to start
- Investigate causes listed under P1
- Check TW_out temperature sensor connection
- Check T1 temperature sensor connection
The full answer, free
- 1 more check in order
- How to put it right, step by step
- The manual page for this fault (page 67), 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
- BHPED PCB failure
- C7Transducer module temperature too high protection
- E0Water flow fault (after 3 times E8)
- E1Phase loss or neutral wire and live wire connected reversely (three phase unit only)
- E2Communication fault between controller and hydraulic module
- E3Final outlet water temp. sensor (T1) fault
- E4Water tank temp. sensor (T5) fault
- E5Condenser outlet refrigerant temperature sensor (T3) error
- E6Ambient temperature sensor (T4) error
- E7Buffer tank up temp. sensor (Tbt1) fault
- E8Water flow failure
- E9Suction temperature sensor (th) error
- EADischarge temperature sensor (tp) error
- EBSolar temp. sensor (tsolar) fault
- ECBuffer tank low temp. sensor (Tbt2) fault
- EDInlet water temp. sensor (Tw_in) malfunction
- EEHydraulic module EEprom failure
- F1Low DC generatrix voltage protection
- H0Communication fault between main board PCB B and main control board of hydraulic...
- H1Communication error between inverter module PCB A and main control board PCB B
- H2Refrigerant liquid temp. sensor (T2) fault
- H3Refrigerant gas temp. sensor (T2B) fault
- H5Room temp. sensor (ta) fault
- H6The DC fan failure