Smart Thermostat Not Working

What's happening?

Smart thermostats like Nest, Hive, Tado, and Honeywell Evohome connect to your Wi-Fi and allow remote control of your heating. When they stop working, you may lose the ability to control your heating from the app or the thermostat itself may be unresponsive.

What usually causes it?

• Wi-Fi connection lost: router issue or thermostat too far from router
• Thermostat battery dead or charging issue (common with Nest)
• Power supply to the thermostat interrupted
• Software or firmware glitch
• Thermostat receiver or hub offline
• Wiring fault behind the thermostat

Is it dangerous?

A smart thermostat that is not working is not a safety concern. However, if your heating is stuck on or off as a result, you may need to use manual overrides until the thermostat is fixed.

Can I fix it myself?

Restart the thermostat by removing it from the wall plate and refitting it, or holding the reset button. Check your Wi-Fi router is working. For Nest thermostats, charge the battery by connecting it to USB. Check the receiver unit (usually near the boiler): make sure it has power and the lights are on. Reinstall the app if it is not connecting.

When should you call an electrician?

Call an electrician if the thermostat has no power and you have checked the supply, if the heating does not respond even with manual controls, if the thermostat was recently installed and never worked correctly, or if you suspect a wiring issue behind the unit.

What will the electrician actually do?

• Check the power supply to the thermostat and receiver
• Inspect wiring behind the thermostat for correct connections
• Test the receiver unit and its relay outputs
• Replace the thermostat or receiver if faulty
• Commission and set up the replacement unit

Questions people ask

Sources & References

1. Energy Saving Trust: Heating Your Home
2. Electrical Safety First: Safety Guidance
3. NICEIC: Householder Guidance