Why does Thermostat mode on Smart AC Control not work?

All I want the Smart AC Control to do is manage temperatures within a comfortable range. If it's above the acceptable limit, the AC unit should run in Cool mode until it brings the temperature down. If it's below the acceptable limit, the AC unit should run in Heating mode until it brings the temperature up. Schedule variations (to change the range) would be nice-to-have, but the above would be sufficient as a starter, even without time variations.

My Ecobees do this so easily; you don't even think about it. They just sit there maintaining the temperature in range. This should be a no-brainer, and sine-qua-non for a Smart AC Control unit. Don't call it "Smart" if it can't do it.

AIUI, this is what Thermostat mode is for. My Smart AC Control appears to have that functionality. I am offered the option in the App, and it is selected. My Acceptance Range is set to 2C. The Minimum On/Off Time is "On (5 min)". But it doesn't work.

All the "Smart" AC Control seems to be able to do is decide when to turn on in the prescribed mode (Heat or Cold) for that period, based on the Smart Schedule for the unit. So if the room is too hot, but the Smart Schedule is set to Heat for that period, Thermostat mode will not tell the AC unit to cool the room (and vice versa).

Maybe there shouldn't be a Smart Schedule, but if I try to delete all periods, it refuses to delete the last one, which covers every period of every day when there's only one period. So that leaves the AC unit set in Heat or Cool mode continuously, even though Thermostat mode should choose the appropriate mode.

In desperation, I long ago kludged the capability by adding a lot of time blocks in the Smart Schedule, every half-hour in daytime hours, switching from Cool to Heat mode and back. At least that will cool for up to half an hour each hour if it's too hot, and heat for half an hour each hour if it's too cold. But apart from being a ridiculous kludge for a "Smart" controller, this is absurdly inefficient and inexpensive, as the AC unit frequently switches between heating and cooling to the target temperature, rather than leaving the unit off unless the temperature is out of range.

[As a supplemental point, tado keep telling how much energy and money the Smart AC Control is saving. That's pure b****cks on this operating pattern. The AC unit is running more than if I controlled it manually. I assume the counterfactual is laughably improbable in order to make it look like the unit isn't a pile of ****.]

I've been struggling with this for a long time. This is a last desperate attempt to see if anyone knows the cause and solution, before I replace the tado with a genuinely "Smart" controller.

Answers

  • What type of AC do you have? I have a MHI AC which has an auto mode. I can choose that auto mode in Tado “standard” mode (non-thermostatic). For my AC I can choose heat, cool, auto, dry and fan in the Tado app. Within auto mode I can choose a certain temperature which is than kept by the airco itself.

  • It's a Dalkia, and it's in Auto mode, according to the remote control. But the tado requires me to choose heating or cooling mode in the Smart Schedule. The Dalkia doesn't run in the opposite way to the mode chosen for the period (i.e. won't cool for any periods that are set to heating mode, and vice versa). I'm guessing that, although my Dalkia remote control shows Auto mode, the tado is setting it to heat or cool according to the schedule, even though the tado is supposedly in Thermostat control mode.

    I've just cycled through the modes on the remote control, starting at Auto and coming back round to it. The Dalkia is now cooling the room, which had got to nearly 26C, even though the target temperature is 21C and the acceptance range is 2C. Clearly, the tado is taking the Dalkia out of auto mode at the start of any Smart Schedule period (i.e. every midnight, as a minimum).

    As I understand the difference between Thermostat and Standard mode, Thermostat mode will maintain temperature within range, whereas Standard maintains temperature towards a target. The former is presumably more efficient and how most people would want a system to function (to avoid short-cycling). The latter reduces the benefit of having a Smart Controller, because, as you note, the AC unit will maintain temperature towards a target without any input from a Smart Controller. All the Smart Control is giving you in that mode is the ability to change the target according to the time or Geofencing, which is nowhere near as significant to me as the efficiency benefit of only running the AC unit when the room is uncomfortably hot or cold.

  • * Daikin, not Dalkia!

  • MichielTado
    edited May 13

    @bgprior I think you are right about the difference between thermostat mode and standard mode. If I understood it correctly, thermostat mode means you let the Tado device determine when the airco is switched on and off (and perhaps also the fanspeed and other things). It “acts” like the thermostat of i.e. the central heating. 

    In standard mode you let the airco decide how to manage the airco temperature. In this mode the Tado device acts like an infrared blaster and replaces the airco remote only, with some additional benefits like homekit scheduling etc.

    I think you should use this standard mode as in that mode the auto mode for the Daikin should be available (as is with my airco). I cannot imaging it being less economical btw. Why would the Tado device be better at maintaining the temperature than the Tado device and be more economical? The Tado device cannot manage the airco modulation anyway.

    What is for you the difference between maintaing a temperature with a range, and towards a temperature? My airco by itself keeps the temperature in the room between 0.1 degrees up or down the setpoint temperature by itself. Do you want it only to switch on when it is too cold or too hot but at different temperatures?

    EDIT: I reread your post again and finally I understand what you want. You want, as you said, a range for the airco to switch on and off. I never had that need, or thought of it before, but understand now why someone might want that. Yes, that is not possible in standard mode. I do not use thermostatic mode so I cannot test it for you unfortunately.

  • I noticed there was an option to "Relearn" the AC commands for Thermostat mode, so I tried that. Lots of repeat attempts, because it asks whether the learning worked, and more often than not, power on/off is back to front, because the instructions you are following don't tell you which it wants first, it just asks you to press the power key and assumes the remote was in the right condition (on/off) that it's learning the right way round. This is epically, Germanically bad design (there was a reason the phrase "Jerry-built" became popular in WW1, and I suggest it's more than due a comeback).

    After all that: no joy. It still works to instruct the unit to heat in Heat mode or cool in Cool mode, but it's too stupid to work out that you want cooling if the temperature is 30C even if it's in Heat mode (or heating if it's 10C even if it's in Cool mode), and too stupid to offer a Mode other than Heat or Cool so it decides the operation mode solely on the basis of the temperature, not a redundant (in this context) control mode. So far as I can see, there is no way in Thermostat mode to get away from the constraint that it is either in Heat mode or Cool mode, and can't cope with switching between one and the other, except on the basis of a Smart Schedule. Catastrophically stupid design, because the useful design would not be difficult logic to implement. There is a hint in this excellent review of the Sensibo Air that this is a known limitation of the tado Smart AC (see reference to 3 modes: Heat, Cool and Off, whereas Sensibo also does Auto): https://www.reddit.com/r/HomeKit/comments/mtztfd/sensibo_air_smart_ac_controller_video/

    So I tried your suggestion and switched from Thermostat to Standard mode. It needs to learn a different set of commands for this, so off we go again. It asks for the brand (Daikin) and model (FTXB25) and even a photo of the remote, but is none the wiser on the back of that. But the good news is it reckons it knows 49 Daikin command codes and just needs to figure out which apply. The bad news is you've got to go through them one by one, seeing if they provoke a response from the AC unit. The worse news is that, in my case, only No.1 was recognised. So we step through 48 other commands for no good reason, other than to learn that tado's claim to suit the European market because it can cope with the wide range of AC units available here compared to America is BS.

    Even though it knows only one code worked, it still invites you to test whether the Smart AC can now control the AC unit. Of course it can't, except On/Off. But in small font, there's an option to teach tado the commands, which I correctly infer will mean pointing the remote at the tado and pressing key sets for various combinations.

    But here we experience more good/bad news. The good news is this is a versatile AC unit with lots of options for different operating combinations. The bad news is the tado wants to know about all of them. I've got 5 operating modes (Heat, Cool, Fan, Dry and Auto). There are 14 temperature steps in cool mode (18-31C, actually 32, but the tado can't handle more than 31C). There are 5 fan strengths plus auto, but again the tado can only handle three fan strengths, so we're going to ignore options 2 and 4 and just program for 1, 3, 5 and Auto. And there is swing on and off. That's 112 permutations just for the options for Cool mode. When we get to the other 4 modes, there are presumably similar numbers of permutations. The bad news is tado wants to step through every one. Each step is several seconds while it reads and stores the signal. At this point, I've done two fan strengths with swing on for Cool mode, and lost the will to live if I've got to do that another 6 times (strong and auto fan with swing, and low, medium, strong and auto fan without swing) before repeating the process for the other modes. The Sensibo Air is around £100, but frankly if you multiply the value of my time by the time it will take to configure this in the forlorn hope it will work adequately, it's better value to buy the Sensibo Air and retire the tado "Smart" AC as the dumb brick that it actually is.

    Of course, I don't really need 14 temperature steps. In cooling mode, 18 to 21C would probably do. I could probably lie to the tado, and reduce the configuration time. But the tado doesn't tell you this is what it's going to do. It just instructs you to find out the available temperature range on the remote, and input it to the tado app, and then uses that to decide the steps it wants you to complete. I could restart the configuration process with this knowledge and lie to it this time, but it doesn't deserve it. I get a lot of smart home equipment to see how they go, knowing they won't all be perfect. They generally range from adequate to excellent. This is one of the few that's so hopeless that no one should consider buying it, in my opinion. Rather than figure out how to make the best of it, I'll take that as a lesson learnt, and advise people accordingly.

    Besides, this is an older Smart AC and therefore doesn't work with Homekit, which the Sensibo will (yes, I know the v3 Smart AC will too, but I never want to see the words tado again). And the Sensibo works better with Home Assistant. I don't know (other than Amazon) who is investing in tado (with all their recent fundraising, which itself ought to be an alert), but fools and their money are soon parted.

  • Postscript: I thought I'd abandon Standard mode configuration and leave it in the Thermostat mode it was configured for, until the Sensibo arrives. But no chance. Once you've started configuring Standard mode, there's no way out other than to complete the process. So I've started going through it again, with the intention of lying to it profusely, and this time it is recognising more of the 49 Daikin commands (around 10/20 so far). Don't know why.

  • In the end, about 20/49 commands recognised this time, which is enough for most functionality without having to teach it all the permutations, so I will see whether Standard mode provides adequate functionality.

  • Weirdly, the Auto mode in the tado option does not allow you to set the target temperature (which is a fundamental part of Auto mode on the AC unit). I have no idea what temperature tado is going to automatically target.

  • * tado app, not tado option

  • @bgprior clearly Tado does not have your specific daikin remote in their database. With my MHI airco I can choose auto mode AND choose a temperature. I also can choose several options for left/right swing and up/down swing. Unfortunately in homekit the choices are much more limited.

    I also had the issue of the Tado app not recognizing my MHI airco remotes. When I contacted support via their chat, after a week or so they had apparently added my specific remote and it worked (without the cumbersome learning experience you had; learning Tado smart AC 112 permutations is weird :-). I needed to provide photos of the remote and the specific airco make and model. I hope sensibo works better for you. After the model was added I only needed to push the on/off button for recognition by Tado.