Hi all, long time tado user with a new setup and need some help!

I've just had a new boiler fitted that is opentherm compatible and I'm having issues getting it up and running properly.

My Tado system consists of:-

V2 internet bridge
Smart thermostat
Extension kit
7 TRV's

All has been running perfectly fine on my old vaillant ecotec plus 831.
I've had an ideal logic max c35 fitted which is openherm compatible.
The extension is wired up to the boiler using the low voltage opentherm connections and set up through the smart thermostat as per the professional installer instructions I.e. D01 as opposed to R01 etc etc.

The boiler runs all the time, mainly pump and fan and doesn't show as opentherm connected in the boiler sensor readings.

If I wire up my smart thermostat direct to the boiler, do away with the extension and trv's and set the smart thermostat to D01 then it works as an opentherm system. It turns on and off as expected and does show on the boiler as opentherm on.

If the extension is wired to the boiler stat connection then it works fine but obviously not modulating through the opentherm.

Any idea what the issue is?


  • Hi, we have a similar setup. Our boiler is an Ideal boiler, for a 3rd Party based on the C35.
    "D01" is for a Wired setup, you need to change this to the "TS" option in step 1, then turn off Hot Water "HW" in step 3, Turn on Extension Kit "EK" in step 4, then set "D01" in step 5, then Save.
    That is the step I followed and as long as your Smart Thermostat is not in the coldest part of your house the heating should stop as expected.
  • Hi thanks for.your reply.
    I sorted the problem by buying a new extension, the early ones must not be opentherm compatible.
    Identical looking and clipped straight into the existing mount.