Heat pumps · Error codes · Cool Energy
VF10Cool Energy · ProInverter (R290, 75C)
VF10 on a Cool Energy ProInverter: Driver board fault: Input phase loss
Short answer
On a Cool Energy heat pump, VF10 means: Driver board fault: Input phase loss. 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: Driver board fault: Input phase loss.
When it shows: Detected after power on; alarm action 'Stop the compressor'.
Likely causes:
- Abnormal input voltage or power failure during operation - check input power supply and wiring.
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
- Abnormal input voltage or power failure during operation - check input power supply and wiring.
- Check supply voltage, phase presence/rotation and balance.
- Check cabling, terminals and MCB/RCBO sizing.
- Check inverter drive/PFC board.
Who to ask for: heat pump electrical.
Certification: Electrical competence (Part P / qualified electrician).
What you might notice
Sources
- Cool Energy ProInverter Monoblock Series R290 Heat Pump Water Heaters - Installation and Users Guide v7.0 (2025) ↗ · Version 7.0 · page 45-46 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026