E10 on a Grant Aerona 290: Communication failure between hydraulic PCB and refrigerant PCB
Short answer
On a Grant heat pump, E10 means: Communication failure between hydraulic PCB and refrigerant PCB. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Communication failure between hydraulic PCB and refrigerant PCB.
Part involved: hydraulic PCB / refrigerant PCB / comms cable.
Likely causes:
- Communication cable incorrectly connected.
- The main hydraulic PCB is faulty.
- The refrigerant PCB is faulty.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: Not stated in DOC 0204.
Manual reset: DOC 0204 s11.1: once the fault is resolved, reset by turning the unit OFF and back ON; s11.5: power cycle can be done from the Aerona Smart Controller touchscreen instead of the external isolator (installer procedure).
What you can check
- Note the exact code shown on the controller display and tell your installer or Grant-trained engineer.
- Check the heat pump isolator switch and the consumer-unit breaker/RCD for the heat pump are ON (do not repeatedly reset a tripping breaker).
What the engineer will check
- Check correct connection of communication cable; replace or repair.
- Check the hydraulic PCB; replace if faulty.
- Check the refrigerant PCB; replace if faulty.
Who to ask for: Grant-trained heat pump engineer.
What you might notice
Sources
- Grant Aerona 290 Air to Water Air Source Heat Pump Range - Installation & Operating Instructions (UK DOC 0204) ↗ · Rev 1.9 · page 55 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026