Smart Thermostat turning on/off constantly


I have just replaced 4 thermostats with Tado Smart Radiator Thermostats in my house on the ground floor. I want to test it, before considering replacing the rest of our old thermostats in the house.

I have a lot of positives to say about our tado-thermostats, but one thing I find a bit annoying and concerning is how it turns on/off the radiator several times during the day.

When the room has reached the target temperature, it turns off the thermostat completely, which concludes that the radiator gets cold. Then when the room temperature gets below 1 degree (approx.) of the target temperature it turns on the thermostat with full power (noise and smell). And that continues..


1.      When it turns on the thermostat on full power, I am afraid that the returning water in the radiator is to hot, which give an extra billing (regelation in Denmark), because it is turned on, on full power.

2.      When our radiator is turned on, on full power (full open) it makes a semi loud sound and this happens quite often doing the afternoon with 4 thermostats. With my old manual thermostats I would just turn them on, so they kept the radiator a bit warm all the time, which make no noise/sound.


Is it not possible with tado thermostat that it turns on the radiator all the time and find the exact level of open, and keep it like this? Instead of turning it on/off all the time?

Or is it something the tado smart thermostat would learn over time?



  • Hi
    I’ve had the same concerns and would love to hear if there is a solution.

    Bw, Peter
  • I've been meaning to ask about this as well. Mainly because the noise wakes me up repeatedly in the early morning when I'm heating up the house (it's 6 am and the heating woke me up at 5:30). Instead of the heating gradually letting hot water into the heater it opens the valve fully with a blast of hot water with huge noise to the radiators. If the can't be fixed soon I'm going back to the old valve in the bedroom at least - have 9 Tados in the house already.
  • Does anyone have a suggestion to help? Thank you!
  • I would like to second this. For a system which is meant to save energy, I think there is a lot of loss which could be prevented by not putting full power on the heating to try and heat up fast.

  • My suggestion to the tado team would be to add additional levels for the radiator thermostats, since currently it can only go to 33%, 66% or 100% open. Often the 33% open is not enough to heat the room, but at the same time 66% is too much and lets a lot of warm water go directly through the radiator without cooling. Especially when the thermostat goes to 100% open a lot of hot water goes directly to waste. So it would be good to have more "manual" control of the how open the valves are. I suspect the concern from tado's side is that the thermostat should not correct too often, so maybe the solution would be for the firmware/software of the thermostats to implement a cooldown to protect the mechanical parts of the thermostats. In the ideal case, there should be API functionality to manually set the valve state to 1%, 2%, ..., 100% open (or even just 10%, 20%, ..., 100%).

  • Thank you for all the reply’s, but I wonder where is Tado? Don’t they have people looking through this forum?


  • I contacted tado's support yesterday, to make them aware of this forum post. The answer I got from the online support was that they could assure me that they would look into this post at some point. So let's see when that will be.

  • Adzyp
    edited February 2020
    I dont know what you're all expecting?? This is how smart TRVs work, the whole idea of a TRV is that it opens to allow water in and when it reaches temp, it closes. If it was left open constantly even if only a little bit then its not smart heating and your radiator will actually be warmer than what you want it to be, never mind the boiler constantly running all day which is not efficient.

    If you want it how you describe, you need to go manual, so not sure what you were expecting to achieve with a smart setup?
  • @Adzyp

    In Denmark, we usually do not have our own boiler, since the majority of Danish homes are connected to district heating. We pay for the amount of hot water that enters our property, and if the water is still 50 degrees when it exits our property, then we are wasting a lot of money on paying for heating that we do not use. This also means that it is not very efficient to set the heating on full power for a few minutes and let the temperature rise several degrees above the wanted temperature, and then let the temperature fall below a threshold before heating again. It would be much more efficient to heat up slowly and later "catch" the temperature from falling, by letting the valve open up on a low level once in a while to keep a stable temperature inside the room.

  • And I would not manually set a valve state of 10%, 20%, ..., 100% open. I would write a script to keep the temperature stable inside all of my rooms, and maybe even based on additional temperature sensors of another brand than tado.

  • @mnauhei of course you would, thats exactly what a manual TRV or even a lockshield valve does. Unless you go round multiple times a day adjusting them?
  • @Adzyp

    How would I make a manual TRV automatically turn down the heat when I am not at home / during the night and then automatically turn it on before I arrive at home / wake up?

    The optimization problem would be to, at any chosen set temperature, keep a steady temperature without wasting hot water going directly through the radiator without heating the room. Of course, when the set temperature is changed from e.g. 18 to 22 degrees (Celcius) it would make sense for the smart TRV to try and reach 22 degrees in the shortest time possible, and not over a duration of several hours. But when the aim is to keep a set temperature of 20 degrees, it does not make sense to wait until the temperature reaches 19 degrees, then do a full power (100%) heat for 15 minutes to make the temperature reach 23 degrees and then cool down to 19 degrees over the next 3 hours and repeat. Then it would be more optimal for the "smart" TRV to find the valve state (e.g. 30%), which keeps the constant temperature of 20 degrees in the room(s). This would actually also reduce stress on the mechanical parts (both TRV and actually the entire heating system).

  • @mnauhei ok, so how exactly do you expect this to work? What i dont get with your theory is how you expect a constant temperature to be kept? The TRV cant do this (no matter how smart it is or isnt, it can either be open or closed, nothing else) and the boiler cant do this as its dumb and will just pump water round at 60 degrees or whatever you are set at
  • I am not sure I understand what you are trying to argue. Tado can currently control the valve to be 33% open, 66% open or 100% open. What I suggest is that they change the software to allow it to be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% open (or even more precise by 5% or 1% increments if possible). Depending on how much the TRV is open, the flow rate of the hot water through the radiator will change. The lower the flow rate, the more the cold air around the radiator will cool the water inside the radiator before it exits the radiator. I agree that the water that enters the radiator will always be approximately 60 degrees (or at least somewhat constant), which is in fact a big advantage when trying to keep a constant temperature in the room while having a constant flow rate of water inside the radiator.

  • samd
    samd ✭✭✭
    edited February 2020

    @mnauhei Hi - Just as an example, I had my heating on this morning for 3 hours. Using a recently calibrated (iced water) thermometer placed on an internal wall opposite both radiators, I can say that the 19c selected only varied by 0.6c during that 3 hours. Remarkable and does not need to be improved in my opinion of course.

  • @samd

    Well, I can also make tado keep a somewhat stable temperature where I live. However, it is simply not possible for tado to do this without letting an insane amount of hot water run directly through my radiator and back to the district heating provider. And this is due to the fact that it insists to fall way below the set temperature before it turns on 100%.

  • samd
    samd ✭✭✭

    @mnauhei OK and my data shown above was with a smart thermostat controlling both radiators. I take your point.

  • @mnauhei ok, maybe its because mine seems to be working a bit differently to yours. If i have a room set to 19 degrees, if it drops to 18 it will call for heat but at heat level 1 out of 3. It wont fall way below before it calls for heat.

    If my room is set to only 15 overnight but then 19 in the morning at 8am. 8am comes and it will kick in at heat level 3 (100%)
  • @Adzyp

    Usually the first case also works for me. However, sometimes it allows to go way below, and then it kicks in with 100% without having started with with 33% or 66%.

    The same is the case for me. Even if my room is set to 17C overnight, and I gradually turn from 17C to 18C, and then 18C to 19C and then 19C to 20C, it will still kick in with 100% everytime and this is actually one of the things that I would like to avoid, in order to be able to heat my apartment without waking up the entire building at 5.30 in the morning. (Yes, it really makes enough noise to wake up all four aparments running on the same heating system). That is why it would really be beneficial to have a better precision on the valve settings.

  • I have the same problem.

    It’s noisy and expensive. And bad for tke climate..

    Tha engineers at tado can make this better...

  • +1 from Denmark, we really need an option to limit flow rates in radiator when on district heating.

    #1 - Because it a key part that the water is returned as cold a possible to "the grid", which is done by circulating slowly so it is cold is leaving the radiator. We gets penalty charges if we don't pull enough heat.

    #2 - To limit noice. District heating comes with very high water pressure, which can be noisy to a degree where you have to turn up the tv. Impossible to use preheating in the morning, it basically works as an early alarm clock :(

    In my opinion the could simply be solved by allowing us to set max flow rate pr. termostat.

    Or more advanced a setting the tries to maintain a temperature with a steady flow rate. I see in the new "Care & Protect" settings that tado should be able to do fine control.

    I love many of the tado features, but this seems like an overlooked issue.

  • +1 more from DK. This is a rather serious issue with an easy fix, as Tranbjerg pointed out, and it is indeed possible to make a much more fine-grained solution for a much higher quality of experience.

    And it is absolute nonsense that “that’s how TRVs work”, then clearly someone doesn’t know the first thing about TRVs. They normally don’t either switch on or off in that very binary way, Tados apparently work. Rather, they increase or decrease the flow, depending on the temperature, keeping the radiator temperature somewhat stable.

    Honestly, I find it hard to believe that a simple fuzzy logic controller (and a few more steps than just 33-66-100%) shouldn’t do the trick.
  • Elaborating a little on Tranbjerg’s quick fix: applying a simple scale factor would be a marvellous improvement. For example, 0.5 for high-flow district heating systems. Then the 33-66-100% would become 17-33-50% instead.

    I imagine this would be a fun little exercise for technical undergraduates... ;o)
  • +1 from Croatia.

    I have 13 SmartRadiatorThermostats and 5 SmartThermostats (4 are for 4 floor heating zones, 1 is 'main' which is connected to boiler).

    I have issues with SmartRadiatorThermostats, they are constantly MAKING NOISE.

    In my living room I have 5 of them. My temp is set to 25 degrees (I tried with 24 also but it is the same principle and same resulting noise) and in the afternoon nap in living room I can't do afternoon nap. Basically every 2-10min I hear one of them working and making noise. And then it gets frustrating like when you have one house fly in the room which your brain then focuses on and hears only that (and is waiting to hear that). This is getting on my nerves recently up to the point that I was thinking about full refund even though I have 13+5 of them.

    Not just that, now this noise is so frustrating that I hear it in my bedroom also (I have 2 in my bedroom) when it starts heating in the morning. This was not a problem before but what living room did to my brain is now affecting rest of the rooms and when I hear that sound I immediately get uncomfortable and then I process that it is the SmartRadiatorThermostat 'doing its work' and why I got uncomfortable.

    I like many Tado features but this one is too much annoying and needs some love from Tado team, please don't ruin good experience that I had until now.

    It has been a full year now since this thread was created. Obviously Tado didn't set hight priority on this issue so that engineers can work on it.

    Please, fix this, then make new features. In this year Tado released another wireless smart thermostat, ok, nice. But fix what you already created and sold and what you hear feedback on.

  • vale4674
    edited December 2020

    Is Tado planning to ignore this for this whole winter? Since that is what happened last winter obviously and now people again are not satisfied when heating season began.

    I contacted Tado support and pointed to this thread. Waiting for reply...

  • Correct, it have now been 1-year and I have not heard anything from tado, absolutely nothing. They will not win best user support for 2020 ;-)

  • It seems all your problems are caused by too much flow passing through the radiators, this would normally be controlled by shutting down the lovkshield partially as was always the case in older uncontrolled set ups where you had to balance the heating between rooms to get an even heat throughout a house.
    It will obviously make the heating slower to take effect in any particular room but the maximum flow once adjusted down to the appropriate level should make everything work more smoothly.
  • Hello, I am not sure if this helps with minimising the flow through the radiators (and thus reducing the return water temperature) but I have recently added a Smart Thermostat to a room containing a number of Smart Radiator Thermostats, and the Smart Thermostat is now used as the temperature sensor for controlling the room temperature. The fact that the temperature feedback is no longer attached to a radiator (as is the case when using Smart Radiator Thermostats) makes temperature control in the room much better and avoids the radiators from cycling through heating/cooling phases.

  • @ceeceedee thanks, I will try this. I have one ST in living room where other 5 SRT are. I set measuring device to one of the SRT because of the logical position in the room (away from windows side of the room) but should be the same temp on both of them (almost same). Setting it now and will monitor through the day. But still this need to be fixed from Tado's side whatever the outcome.

  • +1

    I've create a similar case to Tado. But, sadly currently they do not support this :(

    This is quite a step-down from my 10-year old Danfoss thermostats (They have a configurable preset to handle this pr. radiator)

    The really sad part is, my heating-bill has gone up by about 30% since installing Tado.

    And I get billed extra due to the way to high return-temperature.

    In my case (And I would assume, a lot of other district-heating radiator cases),

    • Tado are more expensive to run - compared to old fashion thermostats.
    • Tado are very unfriendly to the environment - due to the way to high return-temperature.
    • Tado's initial cost are way higher than traditional old fashion thermostats.