Tado V3+ thermostat relay mode
I’ve just installed a wireless Tado V3+ system with the extension kit to control my combi boiler (relay only).
The problem is, that it’s turning the heat on every 10-15 minutes for only 5 minutes, so it turns on even if the temperature only drops by 0,05 degrees. Not sure if this is the intended behaviour, the old non-smart thermostat ran the boiler for about an hour every few hours.
I'm also not sure if a very frequent on-off cycle is good for the boiler.
Also the mobile application’s graph shows only one wavy line (low heat request) 99% of the time, no matter if the boiler is turned on or off. This makes hard to check when the boiler runs or not.
The thermostat is set up correctly with the relay setting (TS, HC01, HW-, Ek+, R01).
Is there any way to change any setting, so the boiler would turn on less ofter, but for longer times? Window detection, early start, geofencing all turned off.
Is this how it works for everyone, or is it some error on my end?
Comments
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That looks quite normal to me. Your old thermostat was probably a traditional thermostat with a large hysteresis between on and off cycles. Tado, like most modern thermostats, uses TPI control for the on/off cycle. This gives better temperature control and is meant to be more efficient. If you click on the Care & Protect menu you should see the real time TPI value calculated for the boiler to maintain the set point temperature. Because the temperature is more constant you may be able to reduce the set point, without the room temperature feeling cooler.
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I have the same problem. I used Netatmo previously and there is possibility to set minimum heating time (2-7 minutes). With tado, the boiler doesn't even heat up the water in the radiators properly and it's turned off. Over and over again. What's the minimum heating time for tado? It would be really great to have an option to set the minimum heating time.
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I suspect the "problem" is that your boiler is overpowered and cannot modulate down low enough to maintain lower flow temperatures.
Unlike old fashioned systems, without smart TRVs, with Tado you might only have one radiator needing heat (plus your bypass radiator). This means that the boiler output cannot be dissipated fast enough. The boiler "overheats" (i.e. reaches set flow temperature) quickly and is forced to shut off. It then overruns the pump for a few minutes before entering anti-cycling mode and delaying restart of the boiler.
This is not the fault of Tado, but it is a consequence of having tight control of each radiator valve when the boiler is too powerful. There is just too much heat and nowhere for it to go. My boiler is max 24 kW, minimum 9 kW. One or two rads can't chuck out 9 kW into an already warm room on a mild winter day.
Before Tado all the valves would be loosely "open" throughout the house. But now you can shut down upstairs entirely during the day and downstairs overnight and easily turn individual unused rooms off entirely. But nobody downsized the boiler when they downsized the heating requirement for the property.1 -
@eezytiger It's not the boiler problem. The thermostat turns on and off within 2-3 minutes. I was listening to the clicking that the thermostat does when it turns on and off.
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@toxicdog Hi, how is your thermostat working now please? Did it learn something and does it work better now? I have similar problem as you did. I had the thermostat connected for 2 days and it constantly turned the boiler on and off for just 2-3 minutes. So I disconnected it and put the old thermostat back.
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Likewise have just installed a V3+ wired thermostat to replace our analogue thermostat, and we found (based on our electricity imports) our heat pump changed from running every 45 minutes to seemingly constantly.
On contacting support they advised they can remotely change the minimum on and off times from the default 3 mins. Apparently this is what they advise for heat pumps, so we now have ours set to minimums of 20 minutes on, 20 minutes off.
I can't find any mention of this anywhere on their main or support websites, but to be fair they've responded really quickly to emails to support. No wonder people give up trying though... If it is this hard, they should just be open and add a support article.
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