Confused! Electrician couldn’t replace existing Thermostat with Wired Tado device?

Hi Everyone,

So we have a new build property with an Ideal boiler which is capable of Opentherm and modulation.

I purchased the Wired version of Tado as I read that it was capable of achieving this via digital set up.

Electrician was round yesterday and when he took off the existing Thermostat, he mentioned that he could set up Tado on relay, however if we wanted the Opentherm/Modulation it wasn’t possible as it mentioned max of 30V.

Anyone come across this before and any suggestions??


  • How far away is the wired thermostat from the boiler?

    Will probably need a separate cable run from the boilers Opentherm terminals to the smart thermostat

  • Thanks for much for your reply @NeonDusk :)

    Quite far I’d say. Boiler is in the utility whereas the original thermostat is in the hallway and I think this is what he mentioned too.

    Is it just better/cleaner to get the EU version in that case? Does that come with everything I need? Will the Tado thermostat just be freestanding in that case i.e. no need to replace the existing thermostat if I didn’t want to? (I probably would anyway but just trying to understand the set up)
  • NeonDusk
    edited February 3

    Just looked at you your other post where you describe your setup. Existing thermostat in hall, combi boiler in kitchen sound similar to mine before I installed Tado.

    When I installed mine I couldn't be sure that the existing cables at the hall thermostat went directly to the boiler. As I didn't want to risk the possibility of connecting mains to Openthem and running a separate cable from the boiler to thermostat wasn't practical I did the following:

    Removed existing thermostat and replaced with Tado Smart thermostat acting as the hall temperature sensor (this could also be the wireless temperature sensor) existing cables are parked here and not used.

    Installed another Smart thermostat next to boiler and ran short length of two core cable between the boiler and Smart thermostat Opentherm connectors. Instead of using a Smart thermostat at the boiler it's possible to use the extension kit (which is now discontinued but you may be able to find someone selling one) or the EU wireless receiver (EU version has Opentherm UK one doesn't). If using the extension kit/wireless receiver you'll need an additional cable supplying mains voltage to power it.

  • This is fab and starting to make a lot more sense so thank you!

    Am I right in saying that I could I essentially just:
    1. Return the wired UK Tado version
    2. Purchase the EU version
    3. Replace my existing thermostat with the Tado version (but not wire it up from the back, purely for aesthetics to remove the old one)
    4. Wire up the extension kit to the boiler directly

    Do you have a link/name of the additional cable required please?
  • NeonDusk
    edited February 3

    Yes. Returning the UK 'Wired Smart Thermostat Starter Kit V3+' and replacing it with 'Wireless Smart Thermostat Starter Kit V3+ (EU Version) - for Combi Boilers' would be best thing to do.

    The EU wireless starter kit should come with cable which can be used for the Opentherm connection. If you do need a cable something like would be fine

    It does come with an EU mains cable to power the wireless receiver which your electrician could replace or change to get the mains power from the boiler instead of plugging into a socket.

  • Have a think about it Tado is for you. The TRVs are NOT representative of room air temperature. As such they heat up quickly due to being on the riser pipe. Gives false readings.
  • @SPT - I just installed 8 x TRVs and they all seem to be reflecting quite accurately. Have you tried recalibrating them?

    Also, what a mess! I have it set up on Relay at the moment because the electrician couldn't work out the Opentherm digital connection - I think my Ideal Logik 35 builder requires an additional part but Ideal won't speak to me without giving them a gas register number which is beyond me.

  • @bearwoodlakes : when you say reflecting nicely. Have you checked the room temperature with an external thermostat or thermometer?

    I did the ideal Logic 38 installation myself it was pretty easy.