Why is my boiler not firing when calling for heat?

I'm an electrician. I've installed my tado extension kit today, everything seems to be working fine but the boiler will not fire when I request heat. Any ideas, please?


  • Sorry to say but you will have to supply a lot more information about your system if you expect to get any further assistance.
  • I've got a Worcester bosch boiler model greenstar 28i junior.

    The old stat and everything else worked fine was just damaged by kids so needed replacing. I've installed the new tado wireless extension kit. As I said that's all connected and seems fine in the app but the boiler will not fire up when I call for heat.
  • Have you wired it on relay? You can post pics if you use the desktop version of the forum.
  • Well I had it set up to combi boiler. The old stat didn't control the water either. I've just set it to relay now but still same problem not firing up boiler when I'm asking for heat. Hot water is running fine just to add
  • Do you have a system or combi boiler? If it’s a combi you wouldn’t be wiring in hot water control. How have you wired the wireless receiver on relay - switched live or volt free? I’ve linked generic instructions below.

  • The Worcester boilers are a different configuration. I took the switched live out of the boiler and put it into LR on the boiler and it fired up straight away. The Worcester boiler didn't follow the same wiring as the diagram provided. Hopefully this will help someone else in the future