Heat pumps · Error codes · Riello
HERiello · NXHM (R32 monobloc)
HE on a Riello NXHM: Communication error between main board and thermostat transfer board
Short answer
On a Riello heat pump, HE means: Communication error between main board and thermostat transfer board. 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 error between main board and thermostat transfer board.
Likely causes:
- RT/Ta PCB enabled but thermostat transfer board not connected or communication not established.
Is it safe?
| 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.
- Restart once via the controller (OFF then ON) as the manual allows; if the code returns, call an engineer.
What the engineer will check
- RT/Ta PCB enabled but thermostat transfer board not connected or communication not established.
Sources
- Riello NXHM Installation and Owner's Manual (IT/EN), cod. 20192830 rev. 0 07/2021 ↗ · 20192830 rev. 0 · page PDF 65 (printed 137) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026