Have I bought the right kit? Tado "Whole home bundle" + Baxi 830 boiler

Hi there,

I'm completely new to Tado but was sold on it when there was an offer on Costco a few months back. We've just bought our new house and are having a new boiler and radiators installed.

The plumber is recommending a Baxi 830 boiler.

The kit I've purchased is:

I've also purchased a couple of extra TRVs.

Can anyone in the know tell me if this will all work well with the Baxi?

I've seen some threads suggesting that some of the tado stuff sold here in the UK isn't fully functional with OpenTherm?

Any pointers before I open any of the boxes Costco supplied would be so welcome.




  • It depends if you're getting a Baxi 830 Combi or Baxi 830 Heat Only. The latter is used with a hot water cylinder.

    If you have a hot water cylinder then you definitely have the correct kit as you will need the twin relay control for CH and HW. If it's a Combi then you won't be able to use Opentherm with that variant of the wireless receiver. Opentherm has a benefit over relay control, but it's not significant.

  • If you want to use Opentherm it will need to be a combi boiler rather then a system (hot water tank) boiler. You’ll need to get either the EU extension kit or the old single button one. Otherwise use what you’ve got with 230v relay. You’ll need to if it’s a system boiler anyway
  • Thanks to you both for your comments.

    It is the Baxi 830 Combi (without a hot water tank).

    I am so new to this stuff - can anyone give me a basic explanation of what features I'd be missing if I used the current kit I have versus ordering the EU Extension kit?

  • With relay control the heating system is either fully on or fully off. The boiler has no idea what the room temperature is and is just blindly responding to the thermostat. If your heating engineer sets the CH water flow temperature to 60°C then the boiler will always aim to supply water at this temperature to the radiators.

    With Opentherm the thermostat is communicating to the boiler by telling it both the room temperature and the required temperature. The boiler will modulate/adjust the CH water flow temperature to suit the conditions. So when the room is cold the boiler will set the CH flow temperature to a high temperature to get the radiators hot and to heat the room quickly. But when the room temperature approaches the required temperature the boiler will reduce the CH flow temperature (e.g. 40°C), which reduces the the radiator temperature and avoids the room temperature exceeding the required temperature. Better temperature control gives better efficiency, plus the lower flow temperature will increase the condensing of flu gases.

    However, smart thermostats learn the characteristics for heating a room/home and use a control mechanism called TPI to mange the relay switching on and off. The end effect is the smart thermostat is predicting when to turn the boiler on and off to avoid the temperature overshoot associated with the old manual thermostats.

    The best thing you can do is reduce the return temperature for water going back from the radiators to the boiler. The cooler the return temperature the more condensing will happen. For a gas boiler condensing will not happen above 56°C. Lowering the boiler's CH water flow temperature and balancing the temperature drop across each radiator will lead to a lower return temperature. Set the flow temperature too low and your radiators will not get the room up to temperature on a cold winter's day.