Interaction between (Wireless) Smart Thermostat and SRV



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]


  • dealj

    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 ✭✭✭
    edited November 2023

    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

    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

    @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 :-)