What is this?
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.
Common causes
- 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 to 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 an electrician 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
Typical cost
£60 – £200
Wiring checks and simple fixes are at the lower end. If the thermostat unit itself needs replacing, add the cost of the new unit (£100-£250 depending on the brand).
