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Riello NXHM fault H1

Communication error between inverter module PCB A and main control board PCB B

Heat pump

What it means

Communication failure between the inverter module PCB A and the main control board PCB B.

Likely causes

  1. No power connected to the PCB or driven board
  2. Wire connection between inverter module PCB and main control board PCB loosened or broken

Where to start

  1. Check the inverter module PCB indicator light is on or off
  2. If light is off, reconnect the power supply wire
  3. If light is on, check the wire connection between inverter module PCB and main control board PCB

The full answer, free

  • 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