Heating not working

I have an installation that has been working for 3 years now. However, I've just started up the heating for the winter and the boiler isn't firing. With the extension kit disconnected, the heating works just fine with the boiler's standard controls. I've had an engineer out today who confirmed that the boiler is ok and the extension kit is wired correctly, but isn't sending the signal to the boiler to start up. The smart thermostat is set to 25 degrees and is calling for heating, both my radiator thermostats are calling for heating too - so there's plenty of signals for heat from the devices.

I've removed all devices from my apple home so they're only active in the tado app. I've tried doing a reset of the bridge (HomeKit enabled one) and reconnecting the extension kit. Everything looks good in the app - all showing connected. The bridge lights are all on. The extension kit light is solid on (doesn't seem to be pulsing like the website says it should). The only thing that looks a little off is the smart thermostat shows arrows in a circle for a second or two before reporting the temperature - I haven't seen that before.

Any ideas? I've reached out to Tado, but so far haven't gotten a response.

Best Answer

  • DanO74
    Answer ✓
    The new boiler is working fine with the extension kit. Must have been a problem with the old boiler. Very happy to have heating again!!!!


  • Update: I tried activating the Extension Kit while it was unpaired. You can press the button on top to turn on the heating full or turn it off when it's in an unpaired state. It didn't do anything, although it did change the light as though it was functioning correctly. Seems like it's either the extension kit or the boiler that have failed. Luckily I'm getting a new boiler next week so we'll find out then.

  • Can you please update us? Was it the Extension kit?

  • Hmmm. I have a similar issue described in another thread:

    I will say, I won't be replacing my boiler just to get this to work. It works fine with the old, "dumb" wireless thermostat.

    But, on the bright side you may have just saved me 100's of € in Tado kit that will be going back to Amazon!

    To the OP, was your old boiler a combi, and if so was it still supplying hot water to taps?

  • Yes, hot water was working fine and the heating worked when I removed the extension kit. The old boiler didn’t have the ability to override the hot water though.

    Did you get hold of Tado? They took a few days, but responded to my support help request eventually and were ready to do some diagnostics from their end. I didn’t need them as the new boiler was being refitted at that point.

  • Thanks for the quick reply!

    I haven't heard anything back from the regular email support, but to their credit when I called the UK support line and left a voicemail that I had lost my heating, a technician called back in a couple hours.

    I installed my Extension Kit connecting to my boiler's 1-2-4 low voltage DC bus. The previous thermostat's wireless receiver had been connected to the 230V AC bus - a simple on/off relay control.

    This was as per the Tado installation instructions, very easy. They mentioned I would have to disconnect the old control wires, but completely neglected the fact that I would need to jump the LS & LR (line supply and return) pins on the 230V relay bus for the heating portion of the boiler to function at all.

    This was what the very competent tech on the phone informed me of. Which, now that I've had to learn more about boiler operation than I ever intended to, makes perfect sense. But would have perhaps been nice to mention in the instructions to a layperson. So I quickly stripped and installed a small jumper and now everything is working fine.

    Tado phone tech: 5 stars.

    Tado email support: 1 star.


  • Glad you got it sorted and you’re rapidly becoming a reluctant expert in boiler wiring!

    The heating engineer that installed my new boiler told me that there’s no way the Tado would work with this system. He even tried to take the extension kit with him because he was convinced it was faulty.

    Luckily I kept it and it took me 2 minutes to install with the new boiler and of course it works perfectly.

  • Good to hear! We bought our apartment recently and the current boiler is working fine but definitely closer to the end of it's life than the beginning. So it's nice to know that when it's eventually replaced a new one should also work fine.


Sign In or Register to comment.

Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!