Do I need Smart Thermostat if all rads have Smart Radiator Thermostats?

Have bought Extension Kit + 8 Smart Rad valves but not yet installed. I was planning to put the Smart Thermostat in the Entrance Hall / Landing, which has two rads with no TRVs, and then have Smart Rad Thermostats in all other rooms. Will this work OK/efficiently, such that in effect the Smart Thermostat is only controlling hall/landing temperature? Would I be better getting Smart Rad Thermostats for the Hall rads too, in which case what would the Smart Thermostat be doing? If there are Smart Rad Thermostats on all rads and no bypass, is that a problem?

Best Answers


  • Thanks @samd. My boiler manual says must have at least one rad with no TRV and must also have a bypass. I've found an automatic bypass is already fitted. So I think for now at least I'll leave the hall and landing rads without control but with Smart Stat in here to cover the situation when it might legitimately call for heat. This compromise is partly as they don't have TRVs currently so avoids a drain down. I can set the Hall schedule for temps below whatever the adjoining set points are and if in the worst case the Hall overheats some at least will dissipate into the adjoining rooms actually calling for heat. Once I've seen how it is performing and the degree of hall overheating, I might bite the bullet and change to something more efficient.

  • Thanks @GrilledCheese - I might do the sensible thing and run this by the gas engineer who services our boiler now - even if not initially planning to put TRVs on everything.

  • Hypnoman
    edited March 2020

    samd wrote:

    tado can work in two different modes:

    1. Tado Boiler-controlling thermostat needs to be calling for heat in order for other tado (and none tado in your case) TRVs to get heat.

    2. Any tado device can call for heat regardless of the boiler-controlling stat.

    I had to ask support (chat line on to change mine to 2nd option above - 2 minute job.

    samd, this is astonishing. Why isn't this mentioned anywhere in their documentation?

    Is it possible to change from one mode to the other myself, or do I have to contact tado and get them to do it for me?

  • Hi @Hypnoman
    From my experience I’m pretty sure my kit was in mode 2 (any device can get boiler to start) out of the box. You can test this easily by setting everything including the Smart Thermostat to say 5deg; wait for boiler to turn off then turn one or more smart radiator thermostats up to max 25. If the boiler starts (may take a few mins) you are in mode 2.
  • samd
    samd ✭✭✭

    @Hypnoman The change has to be made via the chat line on - it's very quick once you are through.

  • Thanks. I wonder why I need a thermostat at all, given that's how it works. At the moment I have most of the rads in the house controlled by smart radiator valves, but those which don't (and have conventional thermostatic valves) are controlled by the main boiler-controlling thermostat.

    Why do I need this boiler-controlling device to be a thermostat? Wouldn't a simple on-off device do the job?

  • I’m also wondering the same thing. Something just seems logically wrong with the whole idea?!
  • Have asked Tado support but they don't seem to be able to answer the question, so will try here.

    I already have TRVs in all my rooms. I now want to buy a wireless receiver/extension kit so that the boiler doesn't have to be always pumping water round the system when none of my radiators are on.

    i) Do I need a smart thermostat/wireless temperature sensor as well as an 'extension kit/wireless receiver'

    (Tado says yes)

    ii) If so, why? Why can't the extension kit/wireless receiver control the boiler by turning it on if any of my smart TRVs are open and calling for heat?

    (unanswered by tado support, who just seem keen to keep telling me that I do need it, without explaining why)

  • Boilerman, it sounds like you were getting the same response that I got last year when asking Tado the same question.

    If by TRV's you mean the Smart Radiator Thermostats (SRT), then it does appear (according to another user on here called TadoUser100) that the if you have SRT's installed and want to use them only to call for heat, that you do not need a Smart Thermostat/wireless temp sensor at all. I am in the same boat here as I use a smart thermostat as the controller when in hindsight it looks like I never needed this at all (as it sits under the stairs where there are no radiators).

    The SRT's talk to the Internet bridge to say I want heat, the bridge tells the extension kit to then fire the boiler.

    I was told by Tado that this wasn't possible (however it didn't seem to me to be likely not the case as the extension kit does indeed have wireless capability to talk to the thermostats).

  • @BOILERMAN yes as @gary333 mentioned I only have smart TRVs, internet bridge and extension kit wired up to my combi boiler (no hot water tank)

    Whenever a radiator calls for heat, boiler turns on heating. When it's up to temperature it turns heating off