Heat pumps · Error codes · Cool Energy
Er25Cool Energy · Inverter range CE-iH (R410A, c.2020)
Er25 on a Cool Energy Inverter range CE-iH: Antifreeze protection
Short answer
On a Cool Energy heat pump, Er25 means: Antifreeze protection. 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: Antifreeze protection.
When it shows: During antifreeze mode, outlet water <=2C warns 'water pump fault Er25' until outlet >=4C (p.21).
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
| 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 heating system pressure gauge reading against the value in your handover documents (manufacturer commissioning values: typically 1-2 bar) and that the filling loop is closed.
- Check the outdoor unit/air grilles are not blocked by debris, leaves or snow.
What the engineer will check
- Check glycol concentration/antifreeze protection.
- Check water flow and outlet temperature sensor.
- Check defrost operation.
Who to ask for: heating / plumbing heat pump installer.
Certification: None specific.
What you might notice
Sources
- 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