Wiring for Wired Smart Thermostat

Hi all. Apologies if this has been asked before......I'm looking to replace my UFH heating thermostat. Tado have suggested using a wired smart thermostat. My UFH wiring centre is marked as Live, Neutral, Earth and Switched Live. How does this correspond to the Tado, which uses NO, NC, COM, P1, P2 and P3?

To make life more complicated, the old receiver for a wireless thermostat in labelled different. But I have the wiring diagram for that and have attached.

Thanks in advance for any support.


  • The mapping between the wiring terminals is:

    • Live to COM
    • Neutral to P1
    • Earth to P2
    • Switched Live to NO (normally open)

    P1 and P2 are parking terminals to safely isolate unused wires. Due to Tado using batteries you only need Live and Switched Live. NC (normally closed) is the opposite of NO. If you connect the wires shown above and the heating is on when it should be off, then move Switched Live to NC.

  • Thanks, really appreciate the help! That is what I had worked out, but really good to have it explained!

    The original wiring has a bridge between Live and Switched Live. Would I also need to bridge between COM and NO?

    Thanks again

  • No, you must not bridge any of the wires on the Tado thermostat.

  • Thanks. Good to know.....do not bridge!!!!

  • daniel23
    edited February 2022

    Hi! I think I have a similar situation, please see the attached wringing diagram.

    Can you please tell me if it correct to link like this?

    • Live to COM
    • Neutral to P1
    • Output (by Live) to NO

    Many thanks


  • Thanks for the info above. still unsure how NO (Normally Off) and NC (Normally Closed) are used

    My current thermostat has 5 wires, RED, WHITE, BLUE(neutral), BLACK, GREEN/YELLOW(earth)

    BLACK = Always 240v (COM)

    Thermostat turned down below room temperature (so the heating is off) RED = 0V, WHITE= 240V

    Thermostat turned up above room temperature (so heating is on) RED = 240V, WHITE =240V

    So my assumption is

    RED = NO (Normally Open circuit)

    WHITE = NC (Normally Closed circuit)


    BLUE =P1


  • For WHITE to be the normally closed circuit it should go to 0v when the thermostat calls for heat and RED goes to 240v.
  • Attach my old controller TS715Si for controlling heating.

    Could anyone can let me know how to wire the NO NC COM P1 P2 P3 and the power of Boiler ?

  • johnnyp78
    johnnyp78 ✭✭✭
    If you use the Tado app to do the install you should get customised instructions.