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What is the relationship between radiator, thermostat and extension kit?

I used to have just smart valves everywhere, the thermostat in the hall, and an old analog style timer in permanently ON position for heating. Worked a charm.

I added the extension kit and can now control HW too - great - except something has changed. The radiator valves no longer turn the boiler on. The thermostat does, but that means I have to heat the hall if I want to heat any other room. This is not cost effective, and not what I wanted.

e.g. My hallway is 19.1, set to 18. My living room is 17, set to 20 - so should be heating but is not. If I override the hall schedule to, say, 20, it kicks in and heats the hallway and the living room.

Is this how this is SUPPOSED to work with an extension kit? If so can I reconfigure it somehow so radiator valves trigger heating, or do I have to rewire something somewhere?

As an aside I am still using the 230V switched (wired) settings as I replaced the thermostat first, and added the extension kit later.

Thanks in advance.

Best Answer


  • Had to do the same with mine when I installed. This is something the end user should be able to manage without having to contact support

    They will change it so any device (thermostat or TRV) can call for heat. You will notice that once done, the room thermostat relay no longer clicks as it's always closed. The heating is turned on/off using the relay in the extension kit

  • Hi there, I have the same set up and issue here whereby the Radiators without Smart TRVS in my home are being heated whenever one of the SMART TRV's ask for heat. Where you able to get this resolved?

    Support just told me it is not possible to resolve and that I either neeeded to fit Smart TRVS to all Rads or just turn down the heaters without Smart TRVS that are controlled by the Smart Thermostat....this seems a little silly to me.

    Any advice would be appreciated.

  • samdsamd ✭✭✭

    @Sebski Support are correct. The only way that I can think of is to have a smart thermostat controlling a zone valve but even that would only work if your non-smart TRVs are on a closed or separate circuit.

  • GrilledCheese answered my question. I asked support and they sorted it within 24 hours and now all works a treat.
  • What is the relationship between smart thermostat and smart rad valves in the same room. Which takes priority? What settings should I adopt?

  • Mog_walsh12, in the default set up, the Smart Thermostat has priority so heating is only turned on if it calls for it regardless of what your Smart Rad Valves might be calling for.

    Tado can change the configuration to give all devices equal priority to call for heat. I believe you must have the extension kit for this to work as it uses the heating relay in that device to turn on/off the boiler

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