Help installing Tado to Baxi combi boiler

I'm trying to install my Tado to my Baxi Duo-tec Combi. Got power going to it but the boiler isn't kicking in. I didn't have an existing thermostat but do have a programmable timer which I've disconnected but not sure if that's right or not.
I've followed the Potential Free diagram so have Neutral wired in with the Neutral wire on my boiler, same with the Live from the Tado into the Live wire on the boiler. I'm assuming that two wires can be connected in the same terminal.
I've connected the black wire from CH NO to terminal 2 on the boiler and then grey wire from CH COM to terminal 1 on the boiler. I'm not sure where I'm going wrong or what to check. Do I need to reconnect the programmable clock?
I did the configuration on the yellow light for combi boiler. When I do the test the heating light comes on but the boiler doesn't kick it.


  • Yes have the official installation instructions
  • johnnyp78
    You might need to bridge the circuit where the timer was, or put it back in set to permanently on.
  • I had the same problem you should have a small u shaped wire that needs to bridge the timer its not power it is a signal that is sent to the programmable timer
    its a signal it is 9 am heat no heat think of it as a loop gone around doing the same thing until say the thermostat needs heat
    The signal changes loop continued until a change
    As your using a wireless room temperature control it takes that loop away from the wired receiver to your boiler
    Hence the need to bridge the timer
    I have a baxi combi boiler had the same problem I asked for more information just came back with same instructions to start with
    I came across by accident as watching instalation I keeped seeing them grouping the old thermostat wires together in a block or twisted together and placing the tado room temperature control
    over the top of the hole covering the wires
    If you need pictures I will try to upload them
  • Do I read this rgiht? Does the old thermostat connection on boiler needs to be bridged with an extra wire?
  • marksabin
    How did you resolve this? baxi does not have the loop on there terminal block, the 2 black wires go elsewhere within the unit