Heat pumps · Error codes · Cool Energy
E2Cool Energy · EcoStore all-in-one exhaust-air DHW heat pump
E2 on a Cool Energy EcoStore all-in-one exhaust-air DHW heat pump: Tank and Wired Controller communication error
Short answer
On a Cool Energy heat pump, E2 means: Tank and Wired Controller communication error. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Tank and Wired Controller communication error.
Likely causes:
- Connection between controller and PCB released or PCB broken.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
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
- 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.
What you might notice
Sources
- Cool Energy EcoStore Heat Pump Water Heater - manual Rev1 ↗ · Rev1 · page 24-26 (printed) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026