Heat pumps · Error codes · Riello
H0Riello · NXHM (R32 monobloc)
H0 on a Riello NXHM: Communication fault between main board PCB B and main control board of hydraulic module
Short answer
On a Riello heat pump, H0 means: Communication fault between main board PCB B and main control board of hydraulic module. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Communication fault between main board PCB B and main control board of hydraulic module.
Likely causes:
- Wire not connected between PCB B and hydraulic module board.
- wrong wire sequence.
- electrical interference.
Is it safe?
Switch the heat pump off at its isolator and call an engineer.
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
What you can check
- Read and note the exact code shown on the controller display.
- Check the heat pump's breaker/isolator at the consumer unit is on.
- If the breaker has tripped or trips again, leave the unit off and call an engineer; do not keep resetting it.
What the engineer will check
- Wire not connected between PCB B and hydraulic module board.
- wrong wire sequence.
- electrical interference.
Sources
- Riello NXHM Installation and Owner's Manual (IT/EN), cod. 20192830 rev. 0 07/2021 ↗ · 20192830 rev. 0 · page PDF 64 (printed 136) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026