Bring back Modulation (OpenTherm) to their wireless thermostat (UK)



  • I've now got the Tado Wired thermostat. My current one is Nest which is two wires into the boiler's open therm terminals.

    I know the tado would wire to the same boiler terminals but am I right in thinking that they are polarity free as I can find no reference about polarity of these two connections?


  • johnnyp78
    Yup, Opentherm is polarity free.
  • Thanks. I'll do it tomorrow, getting too dark now.

  • It didn't work. I

    The installation was easy. The existing wiring from the Intergas boilers two opentherm connectors was simply connected to the Tado wired thermostat opentherm connections + and -.

    Went through Configuration (my Intergas combi boiler is not listed in the table so used the line Various- open therm D0/1.)

    Ran the test. Heated OK but would not switch off.

    Ran config again. No heat.1

    I assume my boiler has its own config menu ID rather than D01.

    Anyone know what the config menu ID should be for an Intergas Combi Compact HRE 36/30, or where I can find this?

  • I was on the cusp of buying all the trv's and thermostats from tado for my house and my mums house. Thankfully a review mentioned tado don't support open therm. I nearly wasted close on £1,000. Come on tado, sell the wireless controller with OT.
  • Klaus_Ludwig
    edited October 2022

    Suggest that anyone who votes for this also votes for "Relay and Opentherm together"

    If I understand correctly, OT will not work properly on Tado Y plan or S Plan systems at the moment, and there are probably a lot of those in the UK...

  • andyblac
    andyblac ✭✭✭
    edited October 2022
  • Thanks @andyblac

    Excellent video.

    I have an open-vented Y Plan system with a Viessmann Vitodens 100-W WB1B heat-only boiler. I would like to go for some type of bus control for improved modulation if that is possible. I have switched live 2 relay control at the moment. Still need to confirm if Opentherm or some other bus control is possible on my system. Both my Wireless Thermostat and Extension Kit have 3 low-voltage terminals that I assume are for bus connections.

  • Just watched the HG video, it mentions Worcester EMS bus, is that on all Worcester boilers? I have a greenstar 30i ErP.

    Is there much advantage over the inbuilt modulation Worcester do based on return flow temp?
  • caj109
    edited October 2022
    Heat Geek spoke to tado in this video and he says it's coming back, can order from the installer website.
  • Miffed I have to pay even more when I thought it came with it.

  • johnnyp78
    @Charliegn52 if you’ve recently bought your equipment you should be able to return it and buy the eu wireless starter kit.
  • rafm5
    rafm5 Volunteer Moderator

    It was officially announced yesterday via social media -

  • I have a heat only boiler on a Y Plan system with Tado controls. Both my master wireless thermostat and my extension kit have Opentherm terminals. Unfortunately the boiler manufacturer (Viessmann) has advised that none of their heat only boilers are compatible with Opentherm due to the 3 way valve control requiring 230v control so I may go for the manufacturers own weather compensation system which includes changing Y Plan to W Plan and adjustable boiler modulation curves relative to outside ambient temperature. I have noted on a You Tube video that EPH manage to combine Opentherm with S Plan. Something that Tado as yet do not offer.

  • Jurian

    @Klaus_Ludwig Your post perfectly illustrates the issue with system boilers and modulating control.

    In the end, Y-Plan/S-Plan systems are only present in the UK and Ireland, and my personal view is that long term this type of wiring should be discontinued in favor of "integrated systems".

    Outside the UK/Ireland, there are also boiler / storage tank combinations, but in those cases, the storage tank always talks to the boiler directly using some form of digital communication and you can just connect any normal digital thermostat to control heating/hot water.

    For the UK/Ireland:

    Tado currently only offers modulating control for systems boilers using the Vaillant VR65 (discontinued, we are not compatible with the VR66) since the VR65 module takes a modulating EBUS signal and translates that to the correct Relay signals for the valves present in S-Plan / Y-Plan.

    And we are compatible with any combi-boiler supporting OpenTherm, Worcester HT_BUS, Vaillant ebus etc... (using either the wired tado thermostat OR the EU version of the wireless receiver)

  • Does anybody know if it is possible to use the OT connections if I have 2 number tado thermostats operating zone valves?

    I take it OT operates instead of a 230v run signal and not as well as it?



  • johnnyp78
    The only way I could think of doing this would be to have a wireless receiver on the boiler connected via Opentherm and then two wired thermostats connected to each zone valve, though then you would have the issue of what to make the zone controller.
  • I believe that my boiler is connected to a 2017 wireless receiver by Opentherm.

    Without checking the connections can I see the configuration of my system via the app or web browser in some way?



  • I was looking for a wireless thermostat setup with opentherm and the tado v3+ looked perfect...until I found this thread and found that the UK version has been crippled with no opentherm capability....sooooooo order cancelled. Time to continue looking elsewhere

  • Just seen there's a link making the EU version available however it's twice the price of the UK version 😐 making it a fair chunk more expensive than other options
  • Hi, I am a bit late to this party (as always lol) In March 2022 I purchased and had fitted a UK Wireless Smart Thermostat Starter Kit V3+ (without opentherm) I now want to upgrade to get opentherm on my system working, I have an Ideal Max Combi C30 boiler (new in 2020) so it has opentherm available, so here is the thing, what do you think my best solution would be:

    1. Swap out my Tado wireless receiver for the add-on wireless EU receiver @ £89.99
    2. or swap it for the WiFi Add-On Thermostat For Multizone Control with OP @ £ 97.97 from Amazon

    If I go for 2, do I leave the receiver from the starter kit V3+ in place and add the wired thermostat as well, or does wired thermostat replace the existing receiver, all the wiring to the boiler is still in place from the existing wired thermostat fitted prior to the Tado stuff.

    My boiler also has its own weather adaption setup wired to an outside sensor, which is running independently to Tado, should I leave this connected?

    Thanks for your valued help

  • andyblac
    andyblac ✭✭✭
    edited January 2023

    @graham35 IMO option 1 would be a simple swap, and as for your weather comp on your boiler you would have to disconnect it (OT would just override it), BUT unless your weather comp is not setup correctly, I don't see the need to replace for OT, as both do basically the same job, WC = Weather Compensation, and OT = Demand Compensation.

  • andyblac Hi Andy thanks for your prompt reply yesterday, I understand what you are saying and if there is no gain for me then maybe I will give up on the idea of opentherm.

    Just as a point of interest, Tado use their own form of weather adaptation/compensation, so would Tado have over ridden my boilers WC in favour for its own WC system. I believe I am getting the use of WC, even though I don't know which, whether it is the Tado or the Boilers WC, as my room use graph shows what I believe is modulation and the use of either 1,2 or 3 flames as necessary to get the room up to the required temperature.

    One further point, if I went for the opentherm, and disconnected the boilers WC, would the Tado system shut down either their own WC or the opentherm if presumably it can only run one or the other?

    I am not questioning whether you are right or wrong, I am just trying to get my head around how these things work and I obviously want the best from my boiler, gas consumption and my money😊. Thanks for your help

  • andyblac
    andyblac ✭✭✭
    edited January 2023

    @graham35 from what I understand (i'm not an expert, other here might be able to advise in more detail), tado˚ controllers only use "Demand Compensation" the more the system (radiators) are demanding heat the more demand is put on the boiler and OpenTherm (OT) uses this demand to modulate the boiler, just like Weather Compensation (WC) does with the outside temperature. As far as i understand all it is either or, either OT or WC you can't use both.

    tado˚ only use weather data to help assist the demand load algorithm, it is not true Weather Compensation, thats why I said if your WC is setup correctly you would probably IMO have more or at least equal saving with your current setup.

    as for the 3 wavy lines line in tado˚, I have found there have no real world usage on OT, by that I mean 1 bar could fire my boiler anywhere between 25-35˚c, 2 bars 30-55˚c, 3 bars 40-80˚c, 1 rad by it self calling for 1 bar could sit at 26˚c flow temp, but 4 rads all at 1 bar could make boiler run at 35˚c, if you get me, so when using OT it best to try have all rad run on same schedule times. I have also found limiting the max flow temp when using OT makes OT inefficient and usage more gas, as if you limit the flow temp OT would ask for heat, realise it take too long and demand more, and it would keep going till it hits the MAX, as OT is trying to heat the room quickly, this is why I have my MAX FLOW rate set to 80˚c. (currently using about 34kWh of gas a day, for heat, hot water, and cooking)

    With WC the demand would not matter, it would be set by outside temp, it would just take longer to heat the room as you would have a lower flow temp, so in WC it best to try not to have fluctuating room temps, ie have a constant day temp and a setback night temp.

  • Simple way round this is to buy the German TADO like i did on the AMAZON.DE website - its about a tenner more because the pound is so weak at the moment.

  • Crazy Tado removed its year 2023 we need more than ever now!

  • I want to check something does opentherm work on system boilers with unvented tank or is this only for combi boilers?

  • johnnyp78
    See my reply in your other thread