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Riello NXHM fault F1

Low DC generatrix voltage protection

Heat pump

What it means

DC bus voltage is below required level, indicating a fault in power supply, main board, inverter board, or rectifier bridge.

Likely causes

  1. Power supply issue
  2. Main board fault (if F1 occurs when compressor starts)
  3. Inverter board fault (if F1 occurs when fan starts)
  4. Damaged IGBT
  5. Damaged diodes in rectifier bridge

Where to start

  1. Check the power supply
  2. Check if LED light is OK
  3. Check the voltage PN - if 380V, problem usually comes from main board

The full answer, free

  • 3 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 67), 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