Interaction between (Wireless) Smart Thermostat and SRV

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HI,

Just installed partial Tado system using (wireless) smart thermostat starter kit + a number of SRV (not yet all fitted).

I'm trying to figure out whether I should have an SRV on the rad in the room in which I have the Smart Thermostat/Temp Sensor placed. And if so, what the role of the Smart Thermostat really ends up playing.

Understand this might seem like a daft question but....

[My system is not a combi boiler, so I am also managing the h/w control through the system]

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  • I may be wrong, but it seems that the smart thermostat (when smart trv's are also used in the house) is used as an interface between the smart trv's and the combi-boiler. But because it's also a thermostat, it can tell the boiler to fire up if the room temp in that room falls low enough. So a smart thermostat in the same room as a smart trv won't work together.....Unless, the smart thermostat is set to frost protect, and therefore the smart trv will open and call for heat according to it's own internal temperature sensor.

  • wateroakley
    wateroakley Volunteer Moderator
    edited November 2023
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    A wireless room stat and smart trv will work in concert. Set the room stat as the measuring device. The first issue to consider is in some homes where you have other rooms with smart trvs and fit the room stat (e.g. in the lounge) that does not have a smart trv. The second issue to consider is whether the boiler needs an external bypass or rad without a TRV.

  • goldfinger
    edited November 2023
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    Thanks, but I'm not entirely following. Coming first to the point as to why have the temp sensor at all ? The TRVs send 'heat' commands direct to the (boiler) receiver directly via the bridge can they not ? So is the temp sensor needed because it is the brains of the hot water control ? (Bearing in mind my system is not combi boiler).

    So then, assuming you have to have the temp sensor and you have it in a room with a TRV. How do you set it up as the temp controller ? And indeed why would you need to as the TRV could just be left to do its own thing - though I guess simplicity of not having separate heating 'schedules' for two devices would be one reason.

    I can see that NOT having a smart TRV in the room where the temp sensor is could be problematic: the rad in that room will be prone to heating (regulated only by its non-smart TRV) as a consequence of any demand being made elsewhere i.e. whenever the boiler is called to heat by any other part of the system.

    A related question. And I'm not sure I want to set it up this way but it will help with my understanding. Is there a way that you can setup heating to be on/off at a whole system level i.e. there is a "master" schedule which says "regardless, only allowing any heating demand to be made if this schedule allows it". I think the answer is no.

    I have to say that while TADO have made installation straight forward, I struggle to find stuff that actually explains how the overall system can and should operate, more difficult to find.

  • wateroakley
    wateroakley Volunteer Moderator
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    @goldfinger To answer ... The starter kits can be used with or without the Tado TRVs. The wireless bridge (for CH/HW or CH/combi), or wired thermostat (for CH/combi), replace your programmer and connect to the zone valves that turn the boiler on. They are a 'zone controller'. A room stat is essential if you have no smart TRVs.

    Assign both devices, room stat and TRV, to the same room. You can set the measuring device in the room settings. The room stat should be the default. The room stat is more accurate than a TRV, +/- 0.1 vs +/-0.5 deg C.

    That's right. Our hallway rad, where the old room stat was situated, does that. It's got the wireless room stat now. Same with our rellies house. To avoid overheating the hall, our rad is throttled by a turn on the lockshield. I left our rellies hall rad alone, it seems to be OK (no complaints from there).

    Whole house? Yes. Like the old controller, room stat and trvs. Set the the room stat as the only device connected in the app room settings to a 'zone controller'. Set all the other TRVs as independent in the app room settings 'not assigned' to a zone controller. The room stat is now the single schedule that will 'call for heat' and the TRVs will act like timed/temperature dumb trvs. You still have control of the HW through the app.

    Yes, it takes a bit of working out what works well for individual homes and personal use. We spent several months tinkering and have found that the seasons are different. We heat individual rooms according our use, have reduced the summer HW ON times and use geo-fencing a lot. These are the results:









    The data and graphs show that we have significantly moved the dial for gas usage. The blue line shows that the best efficiency saving with the old controls was 10-20%. The green line is for the smart controls.

    Some say our results are an outlier. The results correspond broadly to 'price elasticity' research by UCL Energy Institute. Winter demand falls as fuel bills rise ... "Those in the top 20% of consumption reducers reported making much bigger changes to their heating practices, in particular heating homes for fewer hours than before and turning their thermostat down lower."


  • @wateroakley many thanks for that. I will look at it in more depth in due course: I'm currently head down in decorating stuff. This looks to be really informative and should help me to figure out a good setup. Also, its in my nature to want to understand things :-)

  • limeyard
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    @wateroakley, you might be the one to answer my question about the interaction between a Wireless Temperature Sensor and strvs.

    One of my three heating zones includes three spaces of which one - a 'garden room' is subject to wildly (no, widely) variable solar gains. To counter this, the original installation (pre-tado) had dumb trvs on the two radiators in that room as limiters. Since tado, these are now strvs, set to independent operation. Independent, because I don't want them to interfere with the main zone control, a wired thermostat in another room. These improvements have been significant, but trvs of any kind suffer from their proximity to the floor and their proximity to the radiators themselves, not to mention the possibility of being caught by sunlight. So, I am now considering a Wireless Temperature Sensor which is more accurate and - most importantly - can be sited properly. Now for the difficult bit.

    Devices can be given 'Room' names** and, can be 'linked' or 'assigned' to a zone controller, but to be useful in my situation the Wireless Temperature Sensor would need to be set as the controller (of the strvs) in the 'Garden Room'. I cannot see any way that that can be done. Indeed, it seems that the system is unable to do that. Please tell me I'm wrong.

    ** I have discovered by trial that devices do not have to have unique 'Room' names. So, both my strvs are now named 'Garden Room'.

    I hope the above is understandable - any questions, please fire away.

  • davidlyall
    davidlyall ✭✭✭
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    @limeyard I assume your garden room is already set up as a room in Tado with the two TRVs as devices in that room. One of those devices would be set as the measuring device while the other would be a slave to it. If you add a wireless temp sensor, that would then be set as the measuring device and the TRVs would both be slaved to it.

    You can still have the entire room set to be independent or have a zone controller to be able to call for heat

    Hope that makes sense

  • limeyard
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    Thanks for the response @davidlyall . Yes, that superficially makes sense, but how do I make one device the master? For instance, both of my strvs are now called 'Garden Room', but I cannot see any way to make one of them a slave. I have also looked at my wired thermostats' settings and I cannot see a way to select any other device as the 'measuring device'. In all cases, the 'measuring device' is the device itself. Is the Wireless Temperature Sensor different from the other devices? (I don't have one to look myself). Can you share a screenshot where the choice of 'measuring device' is available? tia

  • limeyard
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    I suddenly thought that maybe there was a way to define a room and associate devices to that room - that might be a way to do what I want. But Under 'Rooms and Devices' there is no option to add a room - only 'Add device'.😕

  • davidlyall
    davidlyall ✭✭✭
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    If you go to Rooms and Devices in Settings and select "Garden Room", you should see something like the below

    If you select Measuring Device, it should give you the option to select either of the TRVs to be a measuring device. Once you add a wireless temp sensor to the room, that will appear as an option to be the measuring device

  • limeyard
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    That's brilliant. Presumably, your screenshot is from a system that includes a Wireless Temperature Sensor. None of my devices has that bit. So, it appears that adding a Wireless Temperature Sensor into the system adds those options. However, we can't set up or define a 'Room' per se, only a device that we happen to give a room name. In my case, for each of the two devices, both called 'Garden Room' there would be three devices in the list; the wireless sensor and two strvs.

    Please say if the above is not right. I am most grateful to you for taking the trouble to help.

  • cbd20
    cbd20 ✭✭✭
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    @limeyard you should be able to add both devices to the same room. Unless I've misunderstood, from reading your posts it sounds like you've got two devices assigned to different rooms that just have the same name? You should have a single room called "Garden Room" with a corresponding single tile on the Home screen. If you've got multiple tiles called Garden Room, then you've done something wrong.

    Please note that on the Rooms & Devices screen you can click both the room name and the device name. They give different different options beneath.

  • limeyard
    limeyard
    edited June 17
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    @cbd20, @davidlyall This is interesting. I have repeatedly said that there seems not to be such a thing as 'Room', only devices that are given room names. You have not picked me up on that. Are you really saying that we can define a room and then associate devices with it? That would certainly make sense, but I can't see any way of doing that. My two strvs were originally called 'Garden Room East' and 'Garden Room West' and I renamed them just to see if there was a requirement for unique names. Perhaps I should uninstall one of them and then add it back in to see if it can be associated with the first one's 'room'? Maybe I will then get the option to choose a 'measuring device'

  • limeyard
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    @davidlyall I am so grateful to you for your patience with this. I went to delete one of the strvs but couldn't find a way to do it (does that sound familiar? ☺️). However, I saw an option to move it to . . . another room. So now in the 'Rooms and Devices' list, under 'Garden Room', I have two devices. And if I go to 'Room Name' » 'Measurements'» 'Measuring Device' I am offered two options. Interestingly, I am only allowed to choose one.

    Thank you both for your assistance with this. It is much appreciated. Now I know if I buy a Wireless Temperature Sensor it won't be a total waste of money. Thanks again.

  • davidlyall
    davidlyall ✭✭✭
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    @limeyard glad you got it sorted.

    I did have a suspicion that you had two rooms with the same name but thought that wouldn't be possible. now I see that you had "East" and "West", it makes sense what you were seeing.

  • wateroakley
    wateroakley Volunteer Moderator
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    @limeyard sorry for the delay in replying. Glad to see that other users have helped you with the answer.