Er29 on a Cool Energy heat pump: Return gas temperature sensor fault
Short answer
On a Cool Energy heat pump, Er29 means: Return gas temperature sensor fault. 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 · 3 sources
What it means
On the ecoTech DC Inverter (R32 EVI)
The manual says: Return gas temperature sensor fault.
On the Inverter range CE-iH (R410A, c.2020)
The manual says: Cooling temperature too high fault.
On the Pro Range CE-H (fixed-speed)
The manual says: Faulty compressor suction temp sensor.
Likely causes:
- Compressor suction temperature sensor faulty.
- Sensor plug disconnected/oxidised.
- Controller/PC board faulty.
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
On the ecoTech DC Inverter (R32 EVI)
- Read and note the code shown on the controller display, then contact your installer or service engineer.
On the Inverter range CE-iH (R410A, c.2020)
- 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.
On the Pro Range CE-H (fixed-speed)
- Read and note the code shown on the controller display, then contact your installer or service engineer.
What the engineer will check
On the ecoTech DC Inverter (R32 EVI)
- Check the named sensor/probe connection at the PCB (loose/oxidised plug).
- Measure sensor resistance against the manufacturer table and replace if faulty.
- Check controller/PCB if sensor is good.
Who to ask for: heat pump controls / electrical.
Certification: Electrical competence.
On the Inverter range CE-iH (R410A, c.2020)
- Check water flow rate and temperature sensors.
- Check set-points and system design temperatures.
- Check refrigerant charge.
Who to ask for: heat pump engineer.
Certification: None specific.
On the Pro Range CE-H (fixed-speed)
- Replace or reconnect/clean sensor.
- Replace controller/PC board.
- Check the named sensor/probe connection at the PCB (loose/oxidised plug).
- Measure sensor resistance against the manufacturer table and replace if faulty.
- Check controller/PCB if sensor is good.
Who to ask for: heat pump controls / electrical.
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
- Cool Energy Pro Monoblock Series Heat Pump Water Heaters - Installation and Users Guide Version 5 ↗ · Version 5 · page 25 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026