My tado is consistently overshooting

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I have an issue with our underfloor heating.

Because of the thermal mass the temperature continues to rise for many hours after the tado temperature has been reached.

Some of the cause is that tado does not turn off until about 1° after the desired temperature. We do not have a modulating heat pump (ours doesn’t have that feature).

I would like the thermostat to simply turn off at the target temperature. Is this possible?

Comments

  • tm010
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    Here are the charts

    https://ibb.co/Zzp7T7M
    https://ibb.co/RQk9x08
  • Phillip_PAL
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    Raise a support ticket they will be able to amend the behaviour so that it is more aware of overshoot characteristics.

    In my experience the tado system doesn't have much capability for self learning if any, but works well once its properly configured if the default out of box doesn't cope.
  • GazzaH
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    Hello, is the thermostat in the best location? Is there solar gain from the sun? Is cooking heat or other appliances increasing the Kitchen temperature? Can the flow temperature of the underfloor circuit be reduced in any way at the manifold which would heat the area more gradually and use less fuel as it would have lower flow temps? Can the start times be stepped-up in increments, like 7am go to target of 19C, 7:30 - 19.5C, 8am - 20C? Maybe time it to not be on at mealtimes when heat from cooking may affect it? If you wanted 21C and it overshoots by 1C then you could set it to 20C. Would early start learn how your system heats better? Are you sure the Tado is calling for heat after it reaches the required setpoint. It's very accurate so it would be ignoring ten 0.1C increments if it was still actually calling for heat after reaching setpoint. I think it's more likely to be off at the Tado side but the floor still giving off heat. The same can happen in a house with large radiators or radiators set with too warm a flow temperature - overshooting after the boiler has finished producing heat.

  • GazzaH
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    On 7th April no more heat is being produced by the Tado from about 9am. The graph then noticeably jumps in temperature at lunchtime and dinner time. It rockets up in temperature between 11am and 1pm then rockets again between 5pm and 6 pm. Underfloor heating can't cause peaks and troughs on the graph after it's been off for hours. It would be a gradual heat build up and then a gradual cool down. The floor can't suddenly give off more heat at 11am and 5pm but not inbetween. Other factors are at play here I think. There could also be something like a passing 2 port zone valve for the underfloor loop keeping the heating on but it doesn't explain the jumps unless that's when the other heating zone in the house kicked in and it's accidentally heating the underfloor when the rest of the house's heating is on?

  • GazzaH
    edited April 2023
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    Sat 8th April is different and looks, like you say, the mass of warm floor still giving off heat long after the Tado cut out rather than meal time peaks.

    I still think that lowering the underfloor flow temp is the way to go for gradual heat and no overshooting.

    I take it you have more than one Tado thermostat for this house as the underfloor needs to be on a different zone?

  • tm010
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    Thank you for the replies! Cooking could certainly be a factor, but not really solar gain (north facing). And correct, there are multiple thermostats (but just one in the kitchen, where these temps are taken).

    I've reduced the flow rate to 1l/min via the manifold across all the circuits in the kitchen. Perhaps my next step is to turn some of them off entirely, but then I suspect in the winter that won't give enough heat.

    Staggered increments sadly won't help much - the night time temp was only one degree lower than the daytime.

    Even when I set the temp to all day at 19 degrees the profile was similar - it gets colder at night, UFH takes ages to warm up and then overshoots. I still think it would be better if Tado did at least turn off at the target rather than overshooting - at least that would then reduce the actual overshoot that I see.

    I can't really lower the target temp either to reduce the overshoot, because then the heating will turn on too late and it'll be unnecessarily cold.

    A conundrum :)
  • GazzaH
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    Hello, can you ask your heat pump or underfloor installer what can be done to stop this overshooting?

  • Frank126
    edited April 2023
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    Hi, I have a similar issue here since the tado is installed. I have an underfloor heating (~150square meter) what is heated by a Bosch Tronic Heat 3500 (12kW).

    tado thermostat turns on the heating system once the temperature is under the desired temperature by 0,1C. But because of the thermal mass the temperature is decreasing back ~0,5 Celsius in the next ~2 hours. As example, if the desired temperature is set to 22 Celsius then the tado will turn on at around 21,9 Celsius and it will decrease back to ~21,5 in the next two hours because of the thermal mass. It takes another two hours to reach the desired temperature. Then tado turns off the heating system but because of the thermal mass the temperature will be increased up to 22,5-23 Celsius. From tado point of view the thermostat is working fine because it turns on the heating system once the desired temperature is decreased below the limit and turns off once the desired temperature is reached. The end result is totally different. :)

    I am planning to replace tado thermostat to a bit smarter thermostat what can self-learn the inertia of the heating system (thermal mass) and it may can monitor the temperature of the water inside the heating system. I don't see any other option to solve this issue.

    I have one tado thermostat in the living room (Starter kit - Wireless smart thermostat v3+) but my setup does not follow the recommendation of the below article. I don't want to control the temperature separatelly in the rooms therefore I don't think that my current setup is causing the issue described above.

    https://support.tado.com/en/articles/3482224-how-does-tado-control-underfloor-heating-systems

  • tm010
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    Thanks @Frank126 , sounds like you have a similar problem. Surely Tado can introduce controls to deal with this.

    @GazzaH sadly I don’t know the original installers.
    Thanks
  • davidlyall
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    How long has the system been installed for? I used to find that Tado would overshoot by a long way but gradually it does appear to have learned my house and now turns off the radiator flow sometimes more than 1 deg below set point as it knows that the rad will continue emitting heat and get the room up to temp. I do feel that it's working well for me but I appreciate underfloor isn't as immediately responsive as radiators and holds more latent heat


    I would be tempted to use it for longer just to see if it improves as it learns how your house heats and cools


    Still worth discussing with Tado support to see if they can make any adjustments in the short term that might help save fuel while it's learning

  • tm010
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    Just a quick update - I contacted Tado and they set the relay so that the thermostat only turns on when the three heating arrows are shown, ie there no ‘low’ heating at the beginning and end of the cycle. Will see what impact that has.
  • I've always thought how this would be an issue. I'm surprised there's not an option to say if a room uses a radiator or wet underfloor.
    My system is currently set so the underfloor heating will run whenever the upstairs radiators call for heat.
    World well at the moment.
  • tm010
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    I agree - I don’t really believe the learning capabilities and I think the system should have more manual configurations :)
  • @tm010 just out of curiosity, do you know the thickness of your screed? What temperature do you have the water in your UFH pipework?
  • tm010
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    @mojomoomoo Sadly I don’t know the thickness. The water temp is about 30 degrees at this time of year and the floor temp is about 20/22 I think
  • @tm010 this Tado fix this for you? I’m having the same issue
  • @Lukeobrien92 They made a change but to be honest I never really understood the impact. I’ve now lowered the water temp sufficiently that the heating is always on and doesn’t overshoot…didn’t trust Tado enough!