Smart Thermostat V3 and it's batteries

Just installed a smart thermostat V3 and find it quite silly that the thermostat is sold as a wired thermostat but is battery powered. It seems the only wired part of it is that it switches a relay to activate the always LIVE. But the thermostat itself depends on batteries to work. My existing room thermostat had a complete power circuit including neutral and earth and I had to place those wires in the park terminals. So I basically have power provision where the thermostat is but don't have the option to hard wire the thermostat. Surely Tado should have allowed direct power option. How long does the 3x batteries actually last and I assume if the batteries are dead then relay cannot activate?


  • I’m assuming your old room thermostat was the mechanical type. I think every thermostat with a digital display is battery powered only, I’m yet to find one that isn’t.

  • Rob2
    Rob2 ✭✭✭

    Well, there are different solutions for this. Some smart thermostats have a powersupply located at the boiler, that powers the thermostat via the same wires as are used for the control.

    That solution of using mains power at the thermostat is of course possible, but is likely only used for native thermostats sold with the boiler and installed professionally. The "3rd party" manufacturers like Tado (or Google or others) would not want to use that because it is usually not available and there is a risk when such installations are tampered with.

    The Tado thermostat can be used either wired or in a wireless configuration (with a wireless receiver or extension kit as it was previously called). I presume that is the reason why they use batteries.

    My V3+ thermostat is running on its first set of batteries for nearly 2 years now. But I do not use the relay control, I use OpenTherm. That probably uses less of the battery power.