Ideal
Ideal 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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F1
Thermostat display shows F1 and heating will not turn on
Open Circuit on Heating Call (CH) Output
F10
F10 error and thermostat cannot control hot water schedule
Hot Water Channel Output Fault
F11
F11 displayed and thermostat time and schedules keep resetting
Real-Time Clock / Backup Power Failure
F12
F12 error and thermostat does not respond to touch or button presses reliably
User Interface / Touch Panel Fault
F13
F13 displayed and thermostat shows incorrect date/time zone or cannot sync with cloud
Cloud Synchronisation / NTP Failure
F14
F14 error and thermostat cannot detect any paired wireless sensors or TRVs
Accessory Pairing / Zigbee or Proprietary RF Fault
F15
F15 displayed and thermostat reports internal temperature sensor overheating
Internal Over-Temperature Protection Triggered
F16
F16 error and thermostat cannot detect floor temperature in underfloor heating mode
Floor Sensor Fault (Underfloor Heating)
F17
F17 displayed and thermostat cannot drive zone valve or boiler despite correct wiring
Triac / Solid-State Output Failure
F18
F18 error and thermostat cannot read humidity or shows 0%/100% constantly
Humidity Sensor Fault
F19
F19 displayed and thermostat cannot complete firmware update
Firmware Update / Flash Memory Error
F2
Thermostat shows F2 and cannot control hot water or heating
Short Circuit on Output or Internal Relay Failure
F20
F20 error and thermostat cannot detect presence or occupancy
Occupancy / Motion Sensor Fault
F3
F3 displayed and thermostat does not detect room temperature correctly
Room Temperature Sensor Open Circuit
F4
F4 error and thermostat shows very high or fluctuating room temperature
Room Temperature Sensor Short Circuit
F5
F5 displayed and thermostat cannot detect external temperature for weather compensation
Outdoor Temperature Sensor Fault
F6
F6 error and thermostat cannot connect to the Ideal internet gateway or boiler interface
Communication Failure with Boiler Interface / Gateway
F7
F7 displayed and thermostat cannot connect to Wi‑Fi network
Wi‑Fi Connectivity Failure
F8
F8 error and thermostat cannot detect boiler status or flow temperature
Boiler Data Bus / OpenTherm Communication Fault
F9
F9 displayed and thermostat backlight flickers or unit reboots randomly
Power Supply Voltage Out of Range
Symptom
Heating stays on constantly even when thermostat is set low or off
Stuck Heating Relay or Backfeed in Wiring
Symptom
Thermostat backlight very dim or flickering but unit otherwise works
Display Backlight Degradation
Symptom
Thermostat batteries drain very quickly (weeks instead of months)
Excessive Power Consumption
Symptom
Thermostat buttons or touch areas unresponsive or laggy
User Interface Degradation
Symptom
Thermostat cannot be added to Ideal app or smart home platform
Provisioning / Account Linking Issue
Symptom
Thermostat causes boiler to short-cycle (frequent on/off) even when room not at setpoint
Control Algorithm / Cycle Rate Issue
Symptom
Thermostat clicks and calls for heat but boiler only fires intermittently
Intermittent Control Signal to Boiler
Symptom
Thermostat display completely blank, no lights or response
No Power to Thermostat
Symptom
Thermostat emits buzzing or humming noise when calling for heat
Noisy Relay or Coil Vibration
Symptom
Thermostat fails to control hot water cylinder temperature accurately
Cylinder Thermostat / Sensor Misconfiguration
Symptom
Thermostat frequently disconnects from Wi‑Fi and goes offline in the app
Intermittent Wi‑Fi Connectivity
Symptom
Thermostat loses pairing with Ideal smart TRVs or room sensors
Accessory Link Loss
Symptom
Thermostat or backplate feels unusually warm to the touch
Localised Overheating of Thermostat Electronics
Symptom
Thermostat plastic housing discoloured or warped near terminals
Heat Damage from Overcurrent or Loose Connection
Symptom
Thermostat reboots randomly several times a day
Unstable Power or Internal Fault
Symptom
Thermostat schedules not following set times (heating starts too early or too late)
Scheduling / Optimisation Misconfiguration
Symptom
Thermostat screen on but boiler does not fire for heating demand
No Heat Call from Thermostat
Symptom
Thermostat shows 'Heating On' but radiators remain cold while hot water works
Central Heating Zone Control Issue
Symptom
Thermostat shows room temperature much higher or lower than actual
Temperature Calibration / Sensor Placement Issue
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| F1 |
Thermostat display shows F1 and heating will not turn on
|
Open Circuit on Heating Call (CH) Output | View Details |
| F10 |
F10 error and thermostat cannot control hot water schedule
|
Hot Water Channel Output Fault | View Details |
| F11 |
F11 displayed and thermostat time and schedules keep resetting
|
Real-Time Clock / Backup Power Failure | View Details |
| F12 |
F12 error and thermostat does not respond to touch or button presses reliably
|
User Interface / Touch Panel Fault | View Details |
| F13 |
F13 displayed and thermostat shows incorrect date/time zone or cannot sync with cloud
|
Cloud Synchronisation / NTP Failure | View Details |
| F14 |
F14 error and thermostat cannot detect any paired wireless sensors or TRVs
|
Accessory Pairing / Zigbee or Proprietary RF Fault | View Details |
| F15 |
F15 displayed and thermostat reports internal temperature sensor overheating
|
Internal Over-Temperature Protection Triggered | View Details |
| F16 |
F16 error and thermostat cannot detect floor temperature in underfloor heating mode
|
Floor Sensor Fault (Underfloor Heating) | View Details |
| F17 |
F17 displayed and thermostat cannot drive zone valve or boiler despite correct wiring
|
Triac / Solid-State Output Failure | View Details |
| F18 |
F18 error and thermostat cannot read humidity or shows 0%/100% constantly
|
Humidity Sensor Fault | View Details |
| F19 |
F19 displayed and thermostat cannot complete firmware update
|
Firmware Update / Flash Memory Error | View Details |
| F2 |
Thermostat shows F2 and cannot control hot water or heating
|
Short Circuit on Output or Internal Relay Failure | View Details |
| F20 |
F20 error and thermostat cannot detect presence or occupancy
|
Occupancy / Motion Sensor Fault | View Details |
| F3 |
F3 displayed and thermostat does not detect room temperature correctly
|
Room Temperature Sensor Open Circuit | View Details |
| F4 |
F4 error and thermostat shows very high or fluctuating room temperature
|
Room Temperature Sensor Short Circuit | View Details |
| F5 |
F5 displayed and thermostat cannot detect external temperature for weather compensation
|
Outdoor Temperature Sensor Fault | View Details |
| F6 |
F6 error and thermostat cannot connect to the Ideal internet gateway or boiler interface
|
Communication Failure with Boiler Interface / Gateway | View Details |
| F7 |
F7 displayed and thermostat cannot connect to Wi‑Fi network
|
Wi‑Fi Connectivity Failure | View Details |
| F8 |
F8 error and thermostat cannot detect boiler status or flow temperature
|
Boiler Data Bus / OpenTherm Communication Fault | View Details |
| F9 |
F9 displayed and thermostat backlight flickers or unit reboots randomly
|
Power Supply Voltage Out of Range | View Details |
| – |
Heating stays on constantly even when thermostat is set low or off
|
Stuck Heating Relay or Backfeed in Wiring | View Details |
| – |
Thermostat backlight very dim or flickering but unit otherwise works
|
Display Backlight Degradation | View Details |
| – |
Thermostat batteries drain very quickly (weeks instead of months)
|
Excessive Power Consumption | View Details |
| – |
Thermostat buttons or touch areas unresponsive or laggy
|
User Interface Degradation | View Details |
| – |
Thermostat cannot be added to Ideal app or smart home platform
|
Provisioning / Account Linking Issue | View Details |
| – |
Thermostat causes boiler to short-cycle (frequent on/off) even when room not at setpoint
|
Control Algorithm / Cycle Rate Issue | View Details |
| – |
Thermostat clicks and calls for heat but boiler only fires intermittently
|
Intermittent Control Signal to Boiler | View Details |
| – |
Thermostat display completely blank, no lights or response
|
No Power to Thermostat | View Details |
| – |
Thermostat emits buzzing or humming noise when calling for heat
|
Noisy Relay or Coil Vibration | View Details |
| – |
Thermostat fails to control hot water cylinder temperature accurately
|
Cylinder Thermostat / Sensor Misconfiguration | View Details |
| – |
Thermostat frequently disconnects from Wi‑Fi and goes offline in the app
|
Intermittent Wi‑Fi Connectivity | View Details |
| – |
Thermostat loses pairing with Ideal smart TRVs or room sensors
|
Accessory Link Loss | View Details |
| – |
Thermostat or backplate feels unusually warm to the touch
|
Localised Overheating of Thermostat Electronics | View Details |
| – |
Thermostat plastic housing discoloured or warped near terminals
|
Heat Damage from Overcurrent or Loose Connection | View Details |
| – |
Thermostat reboots randomly several times a day
|
Unstable Power or Internal Fault | View Details |
| – |
Thermostat schedules not following set times (heating starts too early or too late)
|
Scheduling / Optimisation Misconfiguration | View Details |
| – |
Thermostat screen on but boiler does not fire for heating demand
|
No Heat Call from Thermostat | View Details |
| – |
Thermostat shows 'Heating On' but radiators remain cold while hot water works
|
Central Heating Zone Control Issue | View Details |
| – |
Thermostat shows room temperature much higher or lower than actual
|
Temperature Calibration / Sensor Placement Issue | View Details |
No matching codes found
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