Heatmiser
Heatmiser Smart Thermostats Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E01
Thermostat display shows E01 and heating does not switch on
Floor Sensor Open Circuit
E02
Thermostat shows E02 and temperature reading is incorrect or heating locked out
Floor Sensor Short Circuit
E03
Thermostat displays E03 and shows no room temperature, heating output disabled
Internal Air Sensor Fault
E04
Thermostat shows E04 and heating output is locked out
Over-Temperature Protection Triggered
E05
Thermostat shows E05 and cannot control heating correctly
Remote Sensor Open Circuit
E06
Thermostat shows E06 and temperature reading is unstable or locked
Remote Sensor Short Circuit
E07
Thermostat shows E07 and cannot connect to Wi‑Fi or app
Wi‑Fi Module Communication Error
E08
Thermostat shows E08 and fails to join the Heatmiser Neo or cloud service
Cloud / Server Communication Error
E09
Thermostat shows E09 and backlight or display is dim or blank intermittently
Low Supply Voltage / Power Fault
E10
Thermostat shows E10 and cannot control heating zones via wiring centre
Wiring Centre Communication Error
E11
Thermostat shows E11 and fails to pair with NeoHub or RF receivers
RF Communication Error
E12
Thermostat shows E12 and schedules cannot be saved or are lost after power cycle
Non-Volatile Memory Error
E13
Thermostat shows E13 and backlight or touch keys are unresponsive
Touch Panel / Keypad Communication Fault
E14
Thermostat shows E14 and heating output is stuck on or off
Relay Output Fault
E15
Thermostat shows E15 and cannot detect or control the boiler via OpenTherm or digital bus
OpenTherm / Digital Boiler Bus Error
E16
Thermostat shows E16 and fails to control electric underfloor heating load
Load Overcurrent / Triac Protection Fault (Electric UFH Models)
E17
Thermostat shows E17 and time/date keep resetting
Real-Time Clock / Backup Power Fault
E18
Thermostat shows E18 and cannot join Zigbee/Z‑Wave or other smart home network (on compatible models)
Smart Home Radio Module Error
E19
Thermostat shows E19 and cannot control hot water or secondary zone via wiring centre
Zone Mapping / Addressing Error
E20
Thermostat shows E20 and fails to update firmware via app or NeoHub
Firmware Update Error
Symptom
Heating stays on constantly even when thermostat is turned down or off
Stuck Relay / Backfeed in Wiring
Symptom
Radiators or UFH zones controlled by Heatmiser thermostat are hot when they should be off, especially when other zones call for heat
Zone Valve / Actuator Backfeed or Sticking
Symptom
Room temperature reading is significantly higher or lower than actual
Temperature Calibration Error
Symptom
Thermostat buttons or touch screen intermittently unresponsive
Intermittent User Interface Failure
Symptom
Thermostat cannot be discovered or added in the Heatmiser app
App Pairing / Discovery Failure
Symptom
Thermostat cannot control hot water cylinder even though heating zones work
Hot Water Channel Control Fault
Symptom
Thermostat clicks or relay chatters rapidly when calling for heat
Relay Chatter / Unstable Control
Symptom
Thermostat display completely dead, no lights or response
No Power to Thermostat
Symptom
Thermostat does not follow programmed schedule, heating comes on at wrong times
Scheduling / Timekeeping Fault
Symptom
Thermostat frequently overshoots set temperature, room gets too hot
Poor Temperature Control / Overshoot
Symptom
Thermostat is on but does not call for heat even when setpoint is higher than room temperature
No Heat Demand Output
Symptom
Thermostat loses Wi‑Fi connection frequently and drops out of app
Unstable Wi‑Fi Connectivity
Symptom
Thermostat or surrounding wall feels unusually warm to the touch
Thermostat Overheating
Symptom
Thermostat powers on but screen is very dim or unreadable
Backlight / LCD Degradation
Symptom
Thermostat randomly resets or reboots during normal operation
Intermittent Power / Firmware Instability
Symptom
Thermostat shows correct status but boiler does not fire
Boiler Interlock / Control Signal Failure
Symptom
Thermostat shows floor temperature only and ignores room temperature
Incorrect Sensor Mode Configuration
Symptom
Thermostat shows room temperature only and does not limit floor temperature, floor feels excessively hot
Floor Limit Protection Not Active
Symptom
Underfloor heating controlled by Heatmiser thermostat is slow to warm up or never reaches setpoint
Insufficient Heat Output / Flow Issue
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E01 |
Thermostat display shows E01 and heating does not switch on
|
Floor Sensor Open Circuit | View Details |
| E02 |
Thermostat shows E02 and temperature reading is incorrect or heating locked out
|
Floor Sensor Short Circuit | View Details |
| E03 |
Thermostat displays E03 and shows no room temperature, heating output disabled
|
Internal Air Sensor Fault | View Details |
| E04 |
Thermostat shows E04 and heating output is locked out
|
Over-Temperature Protection Triggered | View Details |
| E05 |
Thermostat shows E05 and cannot control heating correctly
|
Remote Sensor Open Circuit | View Details |
| E06 |
Thermostat shows E06 and temperature reading is unstable or locked
|
Remote Sensor Short Circuit | View Details |
| E07 |
Thermostat shows E07 and cannot connect to Wi‑Fi or app
|
Wi‑Fi Module Communication Error | View Details |
| E08 |
Thermostat shows E08 and fails to join the Heatmiser Neo or cloud service
|
Cloud / Server Communication Error | View Details |
| E09 |
Thermostat shows E09 and backlight or display is dim or blank intermittently
|
Low Supply Voltage / Power Fault | View Details |
| E10 |
Thermostat shows E10 and cannot control heating zones via wiring centre
|
Wiring Centre Communication Error | View Details |
| E11 |
Thermostat shows E11 and fails to pair with NeoHub or RF receivers
|
RF Communication Error | View Details |
| E12 |
Thermostat shows E12 and schedules cannot be saved or are lost after power cycle
|
Non-Volatile Memory Error | View Details |
| E13 |
Thermostat shows E13 and backlight or touch keys are unresponsive
|
Touch Panel / Keypad Communication Fault | View Details |
| E14 |
Thermostat shows E14 and heating output is stuck on or off
|
Relay Output Fault | View Details |
| E15 |
Thermostat shows E15 and cannot detect or control the boiler via OpenTherm or digital bus
|
OpenTherm / Digital Boiler Bus Error | View Details |
| E16 |
Thermostat shows E16 and fails to control electric underfloor heating load
|
Load Overcurrent / Triac Protection Fault (Electric UFH Models) | View Details |
| E17 |
Thermostat shows E17 and time/date keep resetting
|
Real-Time Clock / Backup Power Fault | View Details |
| E18 |
Thermostat shows E18 and cannot join Zigbee/Z‑Wave or other smart home network (on compatible models)
|
Smart Home Radio Module Error | View Details |
| E19 |
Thermostat shows E19 and cannot control hot water or secondary zone via wiring centre
|
Zone Mapping / Addressing Error | View Details |
| E20 |
Thermostat shows E20 and fails to update firmware via app or NeoHub
|
Firmware Update Error | View Details |
| – |
Heating stays on constantly even when thermostat is turned down or off
|
Stuck Relay / Backfeed in Wiring | View Details |
| – |
Radiators or UFH zones controlled by Heatmiser thermostat are hot when they should be off, especially when other zones call for heat
|
Zone Valve / Actuator Backfeed or Sticking | View Details |
| – |
Room temperature reading is significantly higher or lower than actual
|
Temperature Calibration Error | View Details |
| – |
Thermostat buttons or touch screen intermittently unresponsive
|
Intermittent User Interface Failure | View Details |
| – |
Thermostat cannot be discovered or added in the Heatmiser app
|
App Pairing / Discovery Failure | View Details |
| – |
Thermostat cannot control hot water cylinder even though heating zones work
|
Hot Water Channel Control Fault | View Details |
| – |
Thermostat clicks or relay chatters rapidly when calling for heat
|
Relay Chatter / Unstable Control | View Details |
| – |
Thermostat display completely dead, no lights or response
|
No Power to Thermostat | View Details |
| – |
Thermostat does not follow programmed schedule, heating comes on at wrong times
|
Scheduling / Timekeeping Fault | View Details |
| – |
Thermostat frequently overshoots set temperature, room gets too hot
|
Poor Temperature Control / Overshoot | View Details |
| – |
Thermostat is on but does not call for heat even when setpoint is higher than room temperature
|
No Heat Demand Output | View Details |
| – |
Thermostat loses Wi‑Fi connection frequently and drops out of app
|
Unstable Wi‑Fi Connectivity | View Details |
| – |
Thermostat or surrounding wall feels unusually warm to the touch
|
Thermostat Overheating | View Details |
| – |
Thermostat powers on but screen is very dim or unreadable
|
Backlight / LCD Degradation | View Details |
| – |
Thermostat randomly resets or reboots during normal operation
|
Intermittent Power / Firmware Instability | View Details |
| – |
Thermostat shows correct status but boiler does not fire
|
Boiler Interlock / Control Signal Failure | View Details |
| – |
Thermostat shows floor temperature only and ignores room temperature
|
Incorrect Sensor Mode Configuration | View Details |
| – |
Thermostat shows room temperature only and does not limit floor temperature, floor feels excessively hot
|
Floor Limit Protection Not Active | View Details |
| – |
Underfloor heating controlled by Heatmiser thermostat is slow to warm up or never reaches setpoint
|
Insufficient Heat Output / Flow Issue | View Details |
No matching codes found
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