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System Boiler Permanently Firing/Running - No Call for Heat


I have a Worcester Bosch Greenstar 8000 Style system boiler connected to a Tado° system with 13 smart TRVs on every radiator in the house, except two towel rails. The system's been running since 2020.

For the last week or so, the boiler's started running constantly - sometimes it just sounds like the fan or pump, but much of the time the flame icon shows on the display indicating it is firing. Although all TRVs are off, there is a gradual build up of heat in many of the radiators - not hot, but noticeably warm. The Tado° app does not seem to show any calls for heat being made from any of the TRVs when I look at the individual history charts, and when the boiler is firing, neither the heating nor the hot water lights are lit on the Tado° control unit (the extension kit wireless receiver directly wired to the boiler).

Any one able to offer any suggestions?




  • SteveIreland

    Sounds like a part of the system is faulty for sure. I would put money on the Control Unit, because if the lights are off, but there is still a call for heat or hot water, it would make sense its your problem………assuming your boiler is not faulty of course and doing this off its own back.

    Might be worth contacting support to see if they can help diagnose.

  • hugbilly
    hugbilly ✭✭✭

    Is this a Y plan system, if so the mid position valve (which is what fires the boiler) might be faulty . . .

  • Emcee
    Emcee Admin

    Hello @NeilJones,

    Thanks for your question and posting on the forum 🙂

    Having had a look at your Home data, it appears that a few rooms in your Home were set to 19° last week and that calls for heat were made when the ambiant temperature dropped below 19°. In other words, the system was working as intended (in theory).

    However, if your Smart Radiator Thermostats were switched off and the app did not show calls for heat, then something might be amiss. The best course of action would be to contact tado° Customer Support to diagnose the cause of these miscommunications.

  • NeilJones
    Thanks for the replies everyone. Whilst digging deep inside the airing cupboard I found another few issues - one of the pressure relief valves is dripping, and there’s also a leak on the outlet pipe from there so I’m going to need to get an engineer in anyway.

    @Emcee thanks for looking into this -I did notice that the temperature did drop a few days ago as you mention leading to a call for heat, but this issue persists with all the TRVs set to off/frost protect as they are currently
  • davidlyall
    davidlyall ✭✭✭

    @NeilJones , if you're finding radiators getting warm even if they are off, the TRVs may not be able to properly close the valve. It could be worthwhile forcing a recalibration by taking the batteries out and re-inserting