replacing a mechanical time switch with tado

Hi, I have just bought the tado wireless starter kit v3 and need a bit of help on the wiring for the boiler switch. At the moment we have an oil fired boiler in an outhouse which is old as the hills (trianco 28/32) and is controlled by a mechanical timer.

The timer has l and n in and l and n go out to the heat pump and to the boiler respectively. When the timer comes on the boiler comes on, if the switch for the ch pump is on radiators are heated too as well as the hot water, so all we do at the moment is turn the ch pump switch off for the summer and manually close a tap valve which closes off the radiators.

I just want to be able to use the tado to switch on the boiler and the ch pump from the house but cannot find any information on how I should wire it to achieve this, l and n into the tado unit I understand but I'm not sure how the wires to the boiler and to the ch pump should go, any help much appreciated because it doesn't seem to be covered anywhere under the tado documentation,


  • It sounds like you have a gravity circulated hot water system, where there is no water pump or valve involved at all for providing hot water, is this correct?

    With a gravity system the Wireless Receiver should be wired with all three Neutral wires connected to the N terminal. The live wire for the central heating pump should be connected to the CH NO terminal. The live wire for the boiler should be connected to the HW NO terminal. Both included purple bridging wires should be installed.

    The Wireless Receiver should then be put into gravity mode by holding down both test buttons on the wireless receiver for 5 seconds and then pressing the heating test button to cycle through the modes until the power LED turns yellow.

  • I suggest you try the gravity-fed dual relay configuration. Connect the boiler switched live to the HW relay (HW NO) and connect the pump live to the CH relay (CH NO). This option means the HW is always turned on when CH turns on. So the CH schedule will always turn on both the pump and the boiler. For the HW only schedule just the boiler turns on. CH only is not an option for this configuration.

    The gravity-fed option is active when the blue LED is illuminated on the wireless receiver.

  • Thanks for that, correct there is no pump or valve for the hot water.

    can i check - neutral feed will have neutral in and neutral out to the boiler and ch-so 3 wires into that terminal

    The only thing i don't understand is where/ how the purple bridging wires should go?

    thanks again, much appreciated

  • Yes the neutral is not switched so all 3 wires connect to one terminal.

    The purple wires should connect the live feed to each of the COM terminals, as in this diagram.

  • Brilliant, thanks to all for your help, very much appreciated.

    I've now got everything wired up, using the test button the pump for ch works but not the hot water. If I test there is voltage across between the neutral in and com on the hw terminals and hw nc terminal but pressing the test button for hw does nothing at all.

    On the ch side the pump comes on and off perfectly, and the fact that there is voltage coming into the com on hw means its wired ok so I can only think the unit is faulty??

  • just to update i swapped the ch and hw no out and now the boiler comes on but not the pump so pretty sure it must be a faulty relay on the hw side, it's going back

  • @sjb

    Did you not get Installation Instructions from tado° for your setup ??🤔

  • No it was not listed in their database and tbh the forum was a lot quicker to respond than sending off photos of my setup.
  • starconf
    edited November 2022


    Sorry, I relise I have given you the wrong information. The power LED should be BLUE for gravity fed. Yellow is for a Combi boiler and the HW relay is disabled in that mode. I am so sorry for misleading you.

  • @sjb
    Are you sorted now ?? 🤔
  • Sort of… I’ve taken it back and exchanged it for a hive. (I was warned off tado for unreliability, I’m going to wire the hive up tomorrow, hopefully will be ok wiring looks very similar so with what I’ve been shown here, thanks to all
  • @sjb
    Getting the correct installation instructions is always the best attempt to "wing it" never works out with this type of technology.