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Thermostat only - when does it call for heat?

edited November 22 in Technical Questions

Greetings all

First time poster - I am considering getting the Thermostat but have a crucial question. Apologies if the answer is documented elsewhere. I have searched before posting and downloaded the app,

Until recently we had an aging dial thermostat which started and stopped the the boiler solely based on temperature. If it seemed slow to react we would turn the dial until it clicked. I hope this sounds familiar to you.

We recently replaced this thermostat with a Honeywell DT90E digital thermostat. Great, we thought, we can see we the temperature is and what it should be accurately. And it does. However the thermostat has a feature we have come to loathe, called TPI https://heatingcontrols.honeywellhome.com/products/temperature-controls/temperature-tpi-control/

This feature maintains the temperature by 'topping up' on a cycle set on the thermostat. Default is every 6 times per hour, but can be 3, 6 or 12. In terms of maintaining temperature it is great.

So the DT90E thermostat now clicks 6, 12 or 24 times an hour as it goes on and off.

So, my question is how does the Tado thermostat work in this regard? Does it click ? Does it cycle on a timed basis? or react based on temperature changes? and can this be configured ?

The thermostat is outside our bedroom door and the clicking is so loud and frequent it wakes us up. We turn it off every night to shut it up...

The question probably applies for the TRVs too but that would be irrelevant if the thermostat is a non-starter for us.


  • Tado does operate in a similar manner to a TPI thermostat. When the room is up to temperature it tops up the heat by cycling the boiler, but it’s a bit more intelligent as it uses additional data to calculate the cycle time. The user cannot alter the cycle time; it is all done by Tado’s cloud computers.

    This may mean that you get similar performance to your current thermostat where it clicks on/off a number of times in an hour. I would describe the relay sound as fairly quiet, but when the house is quiet the sound of the relay is easy to detect.

    The Tado thermostat can operate wirelessly and when it does it is 100% silent. To do this you need to install an extension kit near to your boiler. If you have a CH/HW programmer the extension kit is a direct replacement. The extension kit does click, as it is switching the boiler instead of the thermostat.

  • GrilledCheese2

    Thank you for taking the time to provide a comprehensive reply. I really appreciate it.

    For now I have emptied my Amazon basket of the equipment and will read much more about the extension kits and replacing the programmer. We have a three way programmer currently (UFH, CH, HW) so I suspect this will not be a simple matter if I pursue this.

    But at least I can make an informed decision now. Thank you again.

  • SpecialKSpecialK
    edited November 22

    Looking at the app again, I see Heating can be toggled off and on during the schedule.

    Now I wonder if that by scheduling heating off overnight will mean the thermostat would effectively be "asleep" and not try to maintain temperatures, and therefore not click?

    Suddenly I am bit hopeful again.

    If anyone is able to confirm that scheduling Heating off will actually cause the thermostat to stop its equivalent of TPI, I may rush out to Screwfix!

  • I can confirm if you schedule the thermostat to be off, or at a low temperature during the night then it will remain silent. The relay only clicks on/off during the active part of the schedule. The scheduling is quite flexible and works well.

    As you have a 3 channel programmer you will not be able to swap it for the wireless extension kit.

  • Brilliant. Thank you. Ordered!

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