Hd on a Ferroli heat pump: Communication fault between master unit and slave unit
Short answer
On a Ferroli heat pump, Hd means: Communication fault between master unit and slave unit. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 3 sources
What it means
On the OMNIA LIFE M monobloc R290
The manual says: Communication fault between master unit and slave unit.
On the OMNIA M 3.2 monobloc R32 (4-16 kW and 18T-30T)
The manual says: Communication fault between hydraulic modules in parallel (cascade).
Likely causes:
- Master/slave signal wiring.
- More than one wired controller.
- Power-on interval > 2 min.
- Duplicate addresses.
On the OMNIA S 3.2 split (wall-hung hydronic unit + OMNIA UE 3.2 outdoor)
The manual says: Communication error between hydronic boards (cascade applications).
Part involved: cascade bus.
Likely causes:
- Master/slave signal cables not correctly connected.
- Two or more hydronic boards on one user interface.
- Master/slave start delay > 2 min.
- Duplicate slave addresses.
Is it safe?
On the OMNIA LIFE M monobloc R290
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Manual reset: Manual 13.3: reset the unit by powering it off and on; if resetting is invalid contact the local dealer.
On the OMNIA M 3.2 monobloc R32 (4-16 kW and 18T-30T)
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Manual reset: Manual (13.4): reset the safety by turning the unit OFF and back ON; if unsuccessful contact your local dealer.
On the OMNIA S 3.2 split (wall-hung hydronic unit + OMNIA UE 3.2 outdoor)
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Manual reset: Manual (sect. 10.3): reset the safety device by turning the unit OFF and back ON; if unsuccessful contact the local dealer.
What you can check
- Note the code shown on the user interface and contact the installer/Ferroli service.
- The manual says the safety can be reset by switching the unit OFF and back ON; if the code returns, do not keep resetting - call the installer.
What the engineer will check
On the OMNIA LIFE M monobloc R290
- Diagnose per Ferroli/controller service information (Annex G gives description only; the wired controller shows the explanation).
Who to ask for: heat pump engineer (R290).
Certification: Electrical competence.
On the OMNIA M 3.2 monobloc R32 (4-16 kW and 18T-30T)
- Master/slave signal wiring.
- More than one wired controller.
- Power-on interval > 2 min.
- Duplicate addresses.
Who to ask for: heat pump engineer.
Certification: Electrical competence for board/wiring work.
On the OMNIA S 3.2 split (wall-hung hydronic unit + OMNIA UE 3.2 outdoor)
- Master/slave signal cables not correctly connected.
- Two or more hydronic boards on one user interface.
- Master/slave start delay > 2 min.
- Duplicate slave addresses.
Who to ask for: heat pump engineer.
Certification: Electrical competence for board/wiring work.
What you might notice
Sources
- OMNIA LIFE M - Installation, use and maintenance manual (IT-EN-ES-PT) ↗ · Cod. 3540001560 - Rev. 00 - 07/2024 · page 90 · Reviewed 23 September 2026
- OMNIA M 3.2 mod. 4-16 - Reversible heat pumps for outdoor installation with DC inverter compressor - installation/owner manual (IT-EN...) ↗ · Cod. 3QE47740 - Rev. 02 - 11/2023 · page 71 · Reviewed 23 September 2026
- OMNIA S 3.2 - Installation, use and maintenance manual (IT-EN-ES-PT-FR-DE-NL) ↗ · Cod. 3541V942 - Rev. 01 - 06/2026 · page 126 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026