Er10 on a Cool Energy heat pump: Communication failure of inverter driver module (occurs when communication between outer board and driver board is disconnected)
Short answer
On a Cool Energy heat pump, Er10 means: Communication failure of inverter driver module (occurs when communication between outer board and driver board is disconnected). The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the ecoTech DC Inverter (R32 EVI)
The manual says: Communication failure of inverter driver module (occurs when communication between outer board and driver board is disconnected).
On the Inverter range CE-iH (R410A, c.2020)
The manual says: Self Check.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
What you can check
- Read and note the code shown on the controller display, then contact your installer or service engineer.
- Check the heat pump's breaker/isolator at the consumer unit is switched on (do not repeatedly reset if it trips).
What the engineer will check
On the ecoTech DC Inverter (R32 EVI)
- Check communication cable between controller/PCB/driver board (type, polarity, termination).
- Check power supply to the remote module.
- Replace faulty PCB/controller if wiring is sound.
Who to ask for: heat pump controls / electrical.
Certification: Electrical competence.
On the Inverter range CE-iH (R410A, c.2020)
- Power-cycle / re-initialise parameters as instructed by the manufacturer.
- Check controller firmware/parameters.
- Replace controller/PCB if the fault persists.
Who to ask for: heat pump controls.
Certification: Electrical competence.
What you might notice
Sources
- Cool Energy ecoTech Monoblock Series R32 EVI Heat Pump Water Heaters - Installation and Users Guide v2.1 (2022) ↗ · Version 2.1 · page 31 · Reviewed 23 September 2026
- Cool Energy Inverter Monoblock Series Heat Pump Water Heaters - Installation and Users Guide Version 5 ↗ · Version 5 · page 22 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026