Er5
Heatit
External Room Sensor Out of Range
Display shows Er5 and thermostat cannot control external room sensor
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
External sensor cable extended too far, Wrong cable type causing resistance error, Sensor installed in draft or sun, Defective external sensor element
How to Fix / Troubleshooting
Safety first: Turn OFF power at the breaker before working on sensor wiring.
Steps to troubleshoot:
- 1. Inspect external sensor location:
- Ensure the sensor is mounted at about 1.5 m height, away from direct sunlight, drafts, and heat sources.
- 2. Check cable length and type:
- Verify that the cable length does not exceed the maximum specified in the Heatit manual.
- Use twisted pair or recommended cable type to minimize resistance and noise.
- 3. Measure sensor resistance:
- Disconnect the sensor at the thermostat and measure resistance.
- Compare with the expected NTC curve; replace if out of range.
- 4. Reconfigure sensor type:
- In the installer menu, confirm the correct external sensor type is selected.
- 5. Replace sensor if faulty:
- Install a new Heatit external room sensor and reconnect.
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Repair Difficulty
Medium
3/5
Required Part
Heatit External Room Sensor (NTC)
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