Wired Thermostat & Boiler Controller

I have just installed my Tado wired thermostat as per instructions which went quite smoothly. I still have a boiler controller next to my Vailliant boiler. Somewhere during the installation process I’m sure I read somewhere that I need to set my controller to permanently on to allow the Tado app to control it, but I now can’t find this anywhere. Can anyone give me a lead please?

Thanks in advance.


Best Answer

  • eezytiger
    edited November 21 Answer ✓

    OK. I think it operates as a series of switches. All of them have to be on for the boiler to fire. By setting your controller permanently to "on" it leaves Tado to operate the last remaining switch with final on/off control.

    If the controller was left "off" then Tado could not complete the circuit and the boiler would remain off.


  • eezytiger
    edited November 21

    @gerryryder I'm not sure what you mean by "boiler controller".

    I have a Vaillant Ecotec 831 Plus combi boiler and when I fitted my Tado Smart Wired Thermostat the instructions guided me to remove my existing timer/thermostat (boiler controller?) and to reconnect the pair of switching wires from that into the Tado thermostat. This was using Relay switching.

    To convert to e-Bus required the two wires to be moved within the boiler and the Tado thermostat and then a bridging wire had to be added inside the boiler to set it to "always on" for Tado to control via e-Bus.

    I'm not a heating engineer, but from the little information you've provided I don't understand why your existing "boiler controller" is still part of the equation - shouldn't the Tado wired thermostat have replaced it?

    This is the innards of my old "controller?". Just two wires to be disconnected here and reconnected inside the Tado thermostat once I'd removed the old controller from the wall. Note that they are live at mains voltage if using Relay switching, so obviously the power supply to the boiler needs turning off before meddling.

    For e-Bus control these are the modifications required to my boiler internals to change from Relay to e-Bus. Move two wires and add a bridging loop as shown. The bridging wire is the "always on". Previously this connection would have been an open/close switch operated by the timer/thermostat (or Tado thermostat).

  • Many thanks for your detailed response. I have a wired thermostat in the hallway and a controller next to my Vaillant ecoTec plus 832 boiler which allows be to schedule on/off times. I would post a photo if I knew how to include it in this response.

    Swapping out the wired Drayton thermostat for the Tado one was straight forward. I have now just switched my controller to “ON” and can now schedule on/off times via the Tado app.