Potterton Promax Combi boiler with "Myson touch"

Hello Everyone,

I have 2 Heating Zones (upstairs and downstairs) controlled by individual zone valves wired to a Potterton Promax Combi boiler. Each zone is controlled by a "Myson touch" Programmable WIRED Room Thermostat .

The Upstairs WIRED thermostat is in one of the bedrooms and the Downstairs WIRED thermostat is in the Hallway passage. They are both hard wired into a junction box on the top floor where the boiler is located.

I intend to have TADO smart thermostats to replace the existing WIRED programmable thermostats as well as replace the existing TRV valves with TADO Smart TRV's.

Question is what Tado kit list do I need to replace my existing system ?

I am attaching a pic of the layout for reference.


  • starconf
    edited November 2022

    Hi @Cecil

    I would suggest getting the Wired Smart Thermostat Kit, an add on Wired Smart Thermostat and as many Tado Smart Radiator valves as needed. This will give you all you need for your setup.

    Thanks for the wiring diagram, it makes it much easier to know what is needed.

  • Thanks @starconf for your prompt inputs , pictures helps me to articulate better :)

    I have listed down the below links based on the understanding so far , am I correct ?

    Wired Smart Thermostat V3+ : https://www.tado.com/all-en/wired-smart-thermostat

    Add-on – Wired Smart Thermostat : https://www.tado.com/all-en/wired-smart-thermostat-add-on

    Following the above installation .. add Smart TRV's as needed.

    Am I correct in understanding that the radiator within the vicinity of the wired thermostat shouldn't have a TRV installed to avoid the temperature around the Thermostats being mis-read ?

  • johnnyp78
    johnnyp78 ✭✭✭
    edited November 2022
    You’re thinking about dumb TRVs. For Tado trvs it’s not an issue - if the thermostat is in the same room it becomes the measuring device for the room. Having Tado trvs in the same room gives it more control because it can turn the radiators off for that room rather than just turning off the boiler.
  • To add to this, please see the below picture for reference. I have a few queries in regards to the proposed layout If I go in for the Wired thermostats for both the floors.


    1. The existing "Myson touch" Programmable WIRED Room Thermostats have the Live (COM & L), Neutral and the Switched Live (NO) connections to them.

    2. The TADO back plate has COM,NC & NO

    3. Am I correct in thinking that I will need to use the existing connections Live (COM & L) and the Switched Live (NO) connections only and connect them to COM & NO on both Tado's respectively ?

    4. If my understanding is correct , then I need to isolate the existing Neutral wires as they are not needed ? considering the Tado's are battery powered ?

    5. Does this mean that the Tado thermostats take over the Programming functions that my existing Myson wired thermostats are doing ?

    Thanks in advance for your time.

  • @johnnyp78 I have the radiators connected as depicted in the pic for the room that has the Wired thermostat in it for both floors (The rest have Manual TRV's on them.) .. does this mean that I could install Tado TRV's on these 2 dumb radiators thereby being able to achieve the granular control in every room ?

    The reason I am asking is because currently say for example, if I need the Living room to be warmed up .. I turn off all ground floor radiators (manual TRV's) except the passage radiator as its dumb and doesn't have controls to be switched off . I then raise the temp on the ground floor wired thermostat which is located in the passage. The resulting actions are that the Living room heats up as expected but at the same time the passage radiator heats up as well thereby wasting energy heating up the passage which I do not need.

    The same is the case upstairs , there is a dumb radiator next to the wired thermostat in bedroom 1. If I need bedroom 2 to be warmed up .. the system ends up heating up bedroom 1 as well, thereby losing out on energy consumption.

    Hence I was wondering in my simple mind :) if I get the Tado TRV's installed on all radiators , will it give me the granular control that I am thinking of without worrying about probably damaging the boiler in any way?

  • starconf
    edited November 2022

    Regarding the wiring you are correct about only using the Live and switched Live wires, conencted to COM and NO. The Tado Wired Thermostats have isolated 'parking' terminals labelled P1, P2 and P3 where you can place the neutral wire or any other wires that are no longer used.

    The Tado allows you to set a schedule in the app for each room, this will replace the programming functions from your old thermostats.

  • johnnyp78
    johnnyp78 ✭✭✭
    edited November 2022
    @starconf has answered the wiring question. Those links seem to be referring to dumb trvs. Like I said, with Tado trvs and Tado thermostat it won’t be an issue. Not a bad idea to leave one rad trv free if you don’t have a bypass valve though.
  • @Cecil

    Sorry to say that I cant actually help you......but......just wanted to say that I used to live in Clackmannanshire (The Wee County).

  • The setup has been finally completed , 2 TADO Wired smart thermostats for the Multizone setup with 8 smart radiator TRV's.

    All works well. Its good to have individual room controls per radiator and call for heat as and where needed .

    @starconf & @johnnyp78 Thanks for all your prompt inputs that added to my confidence to complete the setup by myself.

    I also managed to replace 2 radiator valves with TRV's by myself … replace/bleed/repressurize etc .. 😑