Er3
Heatit
Internal Room Sensor Out of Range
Display shows Er3 and thermostat cannot read internal temperature
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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
Thermostat exposed to direct sunlight or drafts, Internal sensor damaged by static or impact, PCB fault in sensor circuit, Installation in recessed or insulated box causing heat buildup
How to Fix / Troubleshooting
Safety first: Turn OFF power at the breaker before removing the thermostat.
Steps to troubleshoot:
- 1. Check installation location:
- Ensure the thermostat is not installed in direct sun, above a radiator, or in a drafty location.
- Relocate if necessary to a more representative room position.
- 2. Inspect wall box:
- Remove the thermostat and check that the back box is not filled with insulation or sealed airtight.
- Provide some air space behind the unit.
- 3. Switch to floor sensor control:
- In the installer menu, set control mode to use floor sensor only (if floor sensor is installed).
- This can bypass a faulty internal sensor.
- 4. Replace thermostat front module:
- If Er3 persists and location is correct, the internal sensor is likely defective.
- Replace the Heatit thermostat front module or entire thermostat.
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Repair Difficulty
Hard
4/5
Required Part
Heatit Thermostat Front Module (with internal room sensor)
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