Mode that emulates a manual TRV behavior for Smart Radiator Thermostat

I wonder whether anyone else would find this useful:

Problem: old leaky house that is unable to retain heat, potentially with mixed heating modes.

Second problem. How to make best use of a boiler firing when zone is not expecting it.

Solution: introduce 2 new modes for Smart TRVs - Passive and Passive Limited.

The idea would be that (for example on a cold night) the TRV would move to a passive mode. This would set the TRV to full open and in the case that another heating zone called for heat, then this TRV would benefit from the heat too. This is for bedrooms where there are several cold rooms but one that needs to stay at a steady temp (baby room) but the other kids rooms would benefit from the heat too.

In a passive (limited) mode, then the behaviour would be the same except that it would cap the temperature of the room. The trv would stay open until a specific temperature was reached and it would then close. This is essentially the same as a normal TRV.
Again this would be for bedrooms.

These passive behaviours would particularly benefit houses with mixed underfloor and radiator heating where the ufh needs to be on several hours before the radiators, but once the boiler is on, it may as well pump hot water to the radiators too, but the heating wouldn’t be on otherwise.
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  • jcwacky

    I'd like this too, but not for the use cases you mention. As the TRVs are pretty noisy when opening/closing, I set my schedule to ensure my bedroom heating never goes on when we're likely to be in bed.

    But this results in a cold bedroom in the morning, and upon waking up I need to manually turn on the bedroom heating.

    With a "passive" mode, I could tell the bedroom to enter a "passive" on state when we go to bed, this would open the TRV, but the room wouldn't heat as all other zones would be off by this time. Then, at 5am when the other zones start calling for heat, as the bedroom valve would be open, it too would start heating and there wouldn't be any noise from the TRV!

  • jcwacky

    @Rbbhghs Don't forget to vote for your idea by clicking the grey up arrow.

  • Rbbhghs
    Nice use case also for the solution.
  • DaveP

    We have a similar situation. Old house (UK) with north facing rooms so they cool down faster but we don't need to explicitly have them at a set temperature all the time.

    But because they can cool down a lot they draw warmer air from the surrounding areas.

    I'd probably put them into "passive" mode when they are not being actively used so they benefit from active rooms.

    i'd also like them to follow a target or maximum temperature and close the valve to prevent over heating.

  • AlexHeylin
    Yes please! I'm using two zones of one TRV each and a multi-room main zone from wall stat. All can call for heat, main zone always gets it and TRVs can shut down at temp. It'd be good for TRVs to preemptively open up a bit if temp is falling in their zone and another zone fires the boiler. Otherwise what can happen is main zone calls for heat, hits set point and shuts off then while system is still warm a TRV calls for heat (causing boiler to fire as system temp below boiler set temp) which reheat whole system and causes overshoot in main zone as well as wasting fuel.
  • jelockwood
    jelockwood ✭✭✭

    It took me a while to understand what was being requested but I now see the benefit.

    Since this does not involve any hardware changes a software enhancement like this even if it is somewhat counter intuitive is worthwhile.

    If the TRVs were quiet enough it would be less important. 💤

  • andyblac

    if you contact tado, they can stop the TRV from calling for heat, it will the act as you described 'Passive Limited' mode, you can set a max temp on the TVR via HomeKit or the Tado app, but it will NOT call for heat, But it is like this all the time, I have had my hall TRV like this for well over a year.

    I asked tado to allow users to do this within a schedule and he agreed it would be a great addition, and said they would look into adding it, But this was well over year ago, and still nothing..

  • ziki

    Tado engineers were not able to made a chilld lock for valves in 4 years...let alone this relative complex feature...sorry, but support were teasing you, as usual.

  • Haresh

    Can Tado please enable an Open option on the radiator valves whereby they remain in the open position and is not controlled by any other device such as the wall smart thermostat?

  • mperedim

    This is also useful in multi-floor setups like mine. Right now I have four different TRVs in second floor (2x bedrooms, 1x office, 1x hallway) which open up and call independently for heat from the boiler. During the night I'd like to still be able to have either one of the bedrooms call for heat, but all four radiators up (so that the temperature at the floor is more even). Others have suggested marking a TRV as "INDEPENDENT", but evidently this doesn't work (during the morning I want the Office TRV to be able to call for heat).

    Ideally this "Open" option will be an additional parameter to temperature, which one can control through smart schedule as well.

  • XKRMonkey

    This is a great idea in principal, and I can see how it can be useful in some scenarios, although each open valve adds to the thermal load on the heating system and correspondingly makes the boiler work harder - no such thing as a free lunch.

    To extend the idea a little, but significantly increase the complexity of the algorithm, the real wins come from "scavenging" heat at the end of a normal heating cycle, or to keep the boiler active when programs have short gaps between them. Pre-emptive opening of a valve in a room that is due to heat soon, whilst shutting down the boiler and just running the pump on to move the hot but now un-needed water through to cold or cooling radiators that will demand heat soon. I think this would effectively be the same as the action to OPEN without actively demanding heat, should be actively used by the system to maximise the use of available energy.

    This could be called "miser mode", and it's more advanced features like this that will ultimately boost the Eco credentials of the product.

    This would require more direct control of the boiler and pump demand mechanism on the boiler, since most boilers control pump behaviour. Interestingly, independent control of the pump and the boiler are also key to good temperature management if you don't have TRVs installed and are relying on a more traditional thermostat control only for room temperature management.

  • o00batman00o

    Please don't make things too complicated. Tado system does not have a close control of the boiler. It acts as a thermostat retuning the ambiant and target temperature of the room that call for heat.

    By using the planning and the boiler advanced settings I can stop the pump while the rooms temp are above target temp.

    For cold rooms that does not need accurate temp control I disabled the heat calling feature.

  • Passive mode is a great idea! I would like some rooms heated if the the heating is on anyway but only at certain time of the day. Other times I would like the TRV to be able to call for heat
  • Bob20
    edited May 2021
    Yes, this would be a great feature and it should also create savings.
  • +1 !

    This would be super useful as described. Asked tado support to configure some TRV's as passive in my home. They can do that be it would be so much better if we could simply do this from within the app.

  • Pete
    Pete ✭✭✭
    Don't understand why anyone would need a trv passive mode?!
    Surely you would just save your money and batteries and screw on a standard mechanical TRV?
  • Jurian
    Jurian Admin
    edited June 2021

    As @GrayDav4276 stated above, I think most use-cases are already covered by setting a room as "independent" via the rooms/devices settings?

    Continuing on the original post:

    Passive mode: Set a room to "independent" and set the temperature to 25 degrees permanently for that room.

    Passive mote (limited): Leave that room permanently on 20 degrees (or the temperature/schedule you desire). And it will only heat up if there is a heat request from one other room that is connected to the "heat source controller".

    This feature, allowing you to link/unlink rooms to the heat source controller at will was introduced a few months back and can be found by clicking on the room name in the rooms/devices settings section in the app or

  • mperedim

    @Jurian as you well know, the "zone controller" setting is not exposed via smart schedule. If you feel that most use cases are covered, would it be too much to ask to move this setting under heating / smart schedule rather than "Room & Devices"

  • Jurian

    @mperedim Since this is something that is a "room based" setting that can't be activated/deactivated per time block, the best place for it to be is in the rooms/devices settings page.

    What would be the use-case to put it in the smart schedule ?

  • Syberyan
    edited July 2021
    @Jurian I think the original post describes some use cases already.
    In my particular case, I’d like all bedroom SRV’s to become passive during the night, so that they don’t activate the boiler individually, but instead benefit from available heat whenever e.g. the baby room (=active mode) calls for heat. However, around wake-up time I’d like them to become active, as to ensure a comfortable temp to get dressed.
    This makes for a much more energy efficient setup (at the cost of some comfort).
  • Hi to all,

    My first post here, so please be patient.

    I guess in common with many of you we're seeing major fuel price hikes this year

    Last year was quite happy with my setup of a Smart Stat in each room (around 10) and had kind of worked out a way to fix the issue where rads were inside covers and the game of setting offsets. Not really happy with that or the faff needed to connect to my Mi room stats for a more reliable reading (in the end I gave up). I played around with Apple homekit etc. but the whole thing was such a pain and time consuming I gave up.

    Anyway, to the point.

    This year I cant afford to call for heat every time one of the 10 rooms drops below the min temp. Basically I want only the Smart thermostat to have the power to fire up the boiler. For the other rooms I just want them to operate as TRVs.

    Before I put traditional TRVs on the rads and ebay all my smart thermostats - is there a way to dumb them down? Maybe using a different gateway for the rads so that they can't burn gas - (ie. that only the master stat can do that).

    Hopefully once I've got my heat-pump installed I can go back to the old setup - but for now I need this.

    Thanks for any advice.


  • jcwacky
    jcwacky ✭✭✭
    @kevinshepherd In the Tado app, go to Settings > Rooms & Devices. Tap on a room name for one of the TRV only rooms and set the “Zone Controller” to “No Zone Controller”. This means the TRV will still open and close based on the set and room temperature but it will not call for heat, so the radiator won’t get hot unless another zone is calling for heat, eg the one with your Smart Thermostat. Is this what you’re trying to achieve?
  • Thanks guys! That sounds like exactly what I was looking for - so glad that I posted my question here :)

    I'll experiment a bit and come back if I get stuck.

    Thanks again.


  • mperedim

    any chance someone in this thread knows how to manipulate the zone status via API?

  • Perfect - win/win/win :)

    Got the problem of Tado V3 bridge not being recognised by homekit.

    Starting to wonder if it's the smart thermostat that I should be adding instead of the bridge...

    Thanks a million guys for all your help so far.

  • andyblac

    it would be nice to control this via schedule, not just via"INDEPENDENT" mode. ie add a tick box to schedule whether to allow call for heat or not in the schedule.

  • @mperedim It is indeed possible to manipulate the zone setting via an API call, just change the setting via a browser and inspect the console ;-)

    I might try to automate this myself. Doesn't look like Tado is going to build this into the schedule anytime soon.