Support current and more recent Vaillant eBus controllers


Tado asserts the benefits of modulating boiler control and touts compatibility with Valiant and eBus. However, the reality is rather grim. It turns out that as of 2019-03 eBus is only supported in these scenarios using the now discontinued VR65 controller. No other controllers are supported (VR66 for example). This means that tado has very limited Vaillant/eBus compatibility and most will be forced to use only binary switched live controls, and not benefit from the additional comfort and efficiency provided by modulated control.

Please can we see some efforts to keep pace with what I imagine is a relatively slow moving target. It is sad that in 2019 one of the leading smart thermostats constrains home owners into choosing outmoded and inefficient control methods.

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  • Hi,

    Unfortunately we have to reverse-engineer most interfaces from scratch as not all boiler manufacturers are interested in a partnership or in assisting an alternative control device to their own, hence it can take time to do so properly (assuming that there are no legal issues preventing us from doing so).

    Best regards,


  • jelockwood

    @teabot @Frank

    I hope Tado do eventually succeed in reverse engineering the new VR66 controller.

    In the meantime another possible but less than ideal solution might be to use the Valiant VR33 OpenTherm conversion module. See -

    This is actually an official Valiant part but is intended only for sale in the Netherlands which may have a local requirement for the use of OpenTherm compatible products.

    Tado is as far as I can tell unique in supporting both eBus and OpenTherm protocols - most other smart thermostats support either OpenTherm and on/off control but not eBus, for example Nest v3 supports OpenTherm but not eBus.

    However be warned even though the above VR33 part is a genuine Valiant part and even if you get it fitted by an approved engineer Valiant will consider this to invalidate any warranty - at least here in the UK.

    Tado regard eBus as being superior to OpenTherm but OpenTherm does still give you the most important benefit of modulated control.

    This news however might lend additional weight to my plans to get a Worcester Bosch boiler instead.

  • Jurian
    Jurian | Admin
    edited November 2021

    @teabot @jelockwood

    As teabot already pointed out, we can control "system boilers" using Vaillant eBus when you use the VR65 mixing module. You might still be able to pick up this module from the 2nd hand market.

    EDIT: THe Smart Wiring Center 2 from Glowworm is NOT compatible with tado. It is based on the VR66.

    The Smart Wiring Center 1 (old discontinued one) should be based on the VR65 and might be compatible.

    Alternatively, you can always opt to for a combi boiler from a brand where we support the digital interface:

  • YoungMJ13

    @Jurian I have a multi-zone system with a combi boiler as the attached diagram. Will 2 tado room thermostats work in this configuration with Glow-worm smart wiring centre 2?

  • mirrormurr

    Got to add me the line of the inquiry if anyone has had success in using the smart-wiring centre on a vaillant or similar system? Got my hand of a v3 Tado start-up set but having a Protherm Gepard gas combi-boiler, I am reluctant to miss out on the possibility to use the modulation-capacity of the system. The alternative is to get a Vsmart Vaillant control or as it is marketed here, the Migo thermostat, with its limited functions, but profiting from its more energy-efficiency.

    regards from CZ, mirrormurr

  • jelockwood

    I was initially puzzled by Jurian's suggestion to use the Glowworm wiring centre since Glowworm is a different brand and one might think the wiring centre was therefore for use only with Glowworm boilers and not Vaillant boilers which was the original query.

    However for anyone else also puzzled by this Glowworm was purchased by Vaillant in 2001. I am still not 100% convinced this means the Glowworm Smart Wiring Centre 2 would work with a Vaillant boiler but it increases the chances it would. It would be a way to use a Glowworm boiler with a Tado Smart Thermostat.

    I found a more complete copy of the manual for the Glowworm Wiring Centre 2 here -

    It still raises other concerns, apart from it looking a lot more complex I would have thought it was possible it might result in any warranty being invalidated. It is already the case that fitting a Vaillant VR33 module to convert a Vaillant boiler from eBus to OpenTherm invalidates the warranty and remember this is a genuine Vaillant part and far easier to fit.

    In my case I am considering a Worcester Bosch boiler instead which like Vaillant uses eBus but unlike Vaillant is apparently still supported by Tado but others might want to look at other brands which support OpenTherm natively e.g. Baxi.

  • After numerous contact with customer support with the confirmation of the compatibility with the eBus system, I took the chance and had the Tado installed for our small Vaillant boiler, the Protherm Gepard, and can confirm the inability of the Tado system to be controlling the temperature of the hot-water and the radiator-temperature.

    Basically, Tado is just an expensive remote on-off switch...-guess I should have gone for Protherms own products, namely the Vsmart or as its called here, the Migo Thermostat. *sigh*

  • AdrianC

    Is there any news on support for the Vaillant VR66? I'm "unfortunate" enough to have one fitted in my new house. Or is there a list or someway I can be notified of updates?

  • jelockwood

    @AdrianC @mirrormurr

    I fortunately have not yet bought a new boiler but all this is convincing me to go for Worcester Bosch rather than Vaillant.

    I think your best option is as previously suggested by Tado to try and find an older VR65 controller module and get that fitted to 'downgrade' your boiler. I did a quick search on eBay and there seem to be a number listed.

    It should be noted there is the potential for a similar compatibility issue with Worcester Bosch. British Gas make a module for Worcester Bosch boilers called Boiler IQ. This module sends diagnostic information to British Gas over the Internet. However if you have this fitted it at a minimum prevents Tado's own diagnostic reporting and might also prevent eBus working altogether.

    Hive an alternative smart thermostat solution has been designed so it can work alongside Boiler IQ. It does this by accessing British Gas' cloud service and downloading the diagnostic information from that. I believe Hive is actually owned by British Gas.

    This is a shame as I might have gone for the Boiler IQ module/service. Thankfully I discovered this in advance.

  • For those of you interested, I’m able to control my Vaillant boiler from Tado. A bit complex to setup but work perfectly...

    in a nutshell:

    • My Tado thermostat is not wired to my Vaillant boiler
    • I’ve setup a node-red flow that periodically check, via Tado API, the requested temperature in each of my rooms vs the current temperature of that room. So I got a delta per room. My script takes note of the highest delta.
    • then my flow talks to my Vaillant boiler using ebusd ruining on my RPI - it “adds” the highest delta to the current temperature in the room where the Vaillant thermostat stands: this causes the boiler to turn on.


    • Room 1: living room with Vaillant thermostat and Tado thermostat and valves
    • Room 2: bathroom with Tado valves
    • Temp in Room 1: 20, asked temp: 20 so delta is 0
    • Temp in Room 2: 18, asked temp: 22 so delta is 4
    • Therefore highest delta is 4
    • Then I take the temperature of the room where the Vaillant thermostat is (20), add the highest delta (4). This gives 24; then I instruct Vaillant boiler that my desired temp is 24.
    • every 30 seconds, routine is executed again


    • Works with all Vaillant equipment supported by ebusd
    • Reliable: have been using it for months without any issue
    • Benefits from the Vaillant regulation


    • If Tado turns down their API, I have a serious issue :)

    if anyone is interested, I could take some time and write a tutorial...

  • jelockwood


    Congratulations. Your effort goes beyond my desire or knowledge, it does however sound like ebusd understands or at least better understands Vaillant's variety of eBus protocol than Tado do.

    This would suggest it might be worth Tado studying the implementation in ebusd for hints on how to resolve their compatibility issue.

    For the benefit of Tado you should look at the following links -

  • stefaanv

    I have bad experience with the Tado system

    I have Tado connected to a Vaillant burner for central heating with radiators and I monitor the communication between the Tado system and the burner with ebusd - many thanks to john30 for his nice software.

    All Tado is doing is switching the old thermostat on and off and setting the flow temperature. Their control strategy is actually very crappy :

    • Tado sets the flow temperature way too high - up to 70° when outside temperature is 10°. Their claim to save energy is very unrealistic with this control scheme. Good for comfort, bad for the wallet and the planet.
    • Tado often (daily) asks heat from the burner while closing all the radiators. On occasion (monthly) my burner makes a very weird loud noise - I suspect cavitation in the circulation pump - so that I have to turn it off and on again. Never had that before the Tado system.
    • Swing in room temperature is high, I see overshoots of up to 1° over the set temperature
    • The systems is non-learning, they actually use a simple PID algorithm.

    The thermostats and the app looks nice, but that's all there is to Tado. Nice branding and marketing, but lousy engineering. They don't deliver the claims they make. Having to pay 2,5€ extra for basic geofencing on/off on top of an already expensive installation is a flat out rip-off.

    My advise : don't buy Tado !

  • jelockwood


    I can't find the forum articles right now I read some and they sound applicable to your situation.

    1. I recall reading that the Vaillant does not advertise the max/target flow temperature to the Tado during initial setup and hence the Tado defaults to an excessive value but in theory over time should learn a better value. This if true would be the fault of Vaillant, indeed I believe the article also said this happened with other brands of thermostat and that the discussion was that Vaillant were not properly implementing the protocol.
    2. Having read the above I contacted Tado about this - more specifically about Worcester Bosch boilers. They said that during initial setup of the Tado it is possible to manually enter an initial target flow temperature but this cannot later be changed. (I would assume that Tado would again 'learn' a better value during continued operation.)

    I am puzzled that if all your TRVs are reporting they are satisfied that your boiler is being turned on. I can only conclude this is because modulated control is 'working' in that it is calling for heat to prevent temperatures dropping too low as there is always a lag. So this could be correct behaviour as long as it does not result in rooms becoming excessively warm. I presume you have also taken in to consideration any Tado Smart Thermostat(s) as well as TRVs as if a Smart Thermostat wants heat then they would obviously have to be obeyed.

  • Mazza

    Folks, I live in the UK and have a Vaillant EcoTec 831 combi boiler (installed over 15 years ago). A few year ago i upgraded the basic thermostat/timer with a Vaillant wireless modulating controller (VR470F) with weather compensation and eBUS modulation. I have asked via the TADO support (ticket 1048047) if my boiler/thermostat combination is eBUS compliant. Ignacio in support replied and said it would work with my setup and all i need is the Tado thermostat and extension kit. Having read the thread here I not entirely convinced it is simple as that. My setup has a Vaillant radio unit that pushes into the main control facia of the boiler using a three pin header interconnect, which talks to a wireless battery powered thermostat/timer.

    My question is, can I just connect the Tado extension unit to my boiler motherboard eBUS terminals and hey presto! I have full control of my boiler including flame modulation like the old Vaillant controller?

  • jelockwood


    Tado would obviously be the best source for a definitive answer but I would expect that if you leave your current weather compensation controller connected this will conflict with Tado. I do seem to recall comments in other forums that weather compensators do cause conflicts - not only with Tado. Similarly if there is some other timer connected this will conflict with Tado's control. Once these are disconnected then I would expect you connect the Tado Extension unit to the eBus terminals.

    What is also worth checking is to see if you can spot a VR65 or VR66 or VR33 module inside your boiler. The VR65 is an eBus controller that should be compatible with Tado. (As much as it can be.) The VR66 is the newer eBus controller which Tado is not compatible with. The VR33 is an OpenTherm to eBus converter which is normally only used in The Netherlands but if present then Tado would be compatible with it and would use OpenTherm rather than eBus.

    Note: As mentioned weather compensation modules do cause a conflict - not only in Vaillant boilers. For this reason smart thermostats use Internet accessed weather information to perform the same function based on your post code. However you still need to remove the weather compensation module as otherwise both it and the smart thermostat 'fight' each other. I have suggested Tado add support for the Netatmo smart weather station as a local weather source.

  • Mazza

    @jelockwood. thanks for the advice. TADO support replied back. I just wire the extension unit directly into the eBUS on the motherboard and it should work fine. fingers cross. I will reply back on here on how it went.

  • EdGi

    Watching this with interest - I've just purchased Tado thermostat & extension to connect to a Vaillant ECOtec 831 like @Mazza and was expecting proportional control, and some degree of 'smart' control with a 'smart thermostat' so we will see.

    I'd say @beetlejuice is on the right track though it's not someting that everyone can do.

  • EdGi

    I can confirm that an 11/2019 Tado 3+ does apply modulated control to a U.K. Vaillant EcoTEC+ 831 boiler.

    The Tado requests an output temperature of the boiler (as seen in the boiler diagnostic display), which does vary depending on current/required temperatures.

    That's great, though I did ask technical support if it did actually do this, and didn't get a reply.

  • smgeee

    I agree with EdGi.

    Recently installed (September 2020) a Tado V3+ to a Vaillant ecoTEC Plus 838 using a wired eBus connection from the thermostat straight into the boiler. It's a UK boiler, just about 2 years old. The thermostat is running firmware version 67.2.

    The Tado modulates the boiler output flow temperature as required. As the weather is still mild, there is a low heating demand and I've seen flow temperatures (on the boiler display) in the high 20s-low 30s Celsius.

    Incidentally, the Tado replaces a Vaillant VRC700f (wireless thermostat with wireless outside temperature sensor) which was an utter piece of junk, in both basic function and performance. So far the Tado is an enormous improvement. I'll see how it performs when the weather gets colder.

  • gary333
    gary333 ✭✭✭
    edited October 2020
    On my Vaillant Ecotec 938 (basically a 838 with tank) whatever heating temperature you set in the Vaillant boiler control panel is what the boiler will be limited to. Thus if set to 65oC on the boiler, the Tado at 100% / 3 bars will be limited to 65oC.

    The boiler cannot accept under 35oC requests thus Tado in minimum setting of 1 bar could be going as low as 35oC (something i see happening a lot for temperature “top ups”).

    It would be better if tado could be a little smarter on the flow temperature request so the default Vaillant 75oC could be left in place, however i found this with around good enough. Just means i might have to turn it up in winter. Time will tell as it gets colder.
  • Anouj

    On my ecotec pro 28 the ebus connected tado is detected by the boiler but the tado is only requesting 30 Celsius which isn’t doing much to heat the house. Anyone know why this is?

  • RayA
    edited October 2020

    I recently bought the Tado V3+ starter kit with two smart TRVs, to be installed on my Vaillant ecoTec Pro 28, which is currently controlled by Vaillant's VRT-350F wireless thermostat. Through my research and limited knowledge in this area, I understood that I don't need an extension kit coz the boiler is already controlled by a wireless thermostat.

    Could someone please guide me how to make the Tado thermostat communicate with the VRT-350F's receiver unit fitted on my boiler? Thanks much.

  • jelockwood


    The following applies to all boilers.

    It is possible to connect a Tado Thermostat directly to a boiler without an Extension unit. If you look on the back of the Tado Thermostat you will see it has a standard (Drayton style) mounting plate with wiring connections. It supports either old-style 'call for heat' wiring which is possible with the Vaillant but it also supports newer eBus/OpenTherm wiring and Vaillant supports eBus.

    eBus/OpenTherm uses just two wires. These would have to be connected to the Vaillant boiler. If you use the Tado setup wizard it should generate wiring instructions for you.

    The Tado Thermostat would talk to the Tado TRVs wirelessly. It would not talk wirelessly to the boiler.

    Note: The Tado Thermostat by itself only controls central heating heat, not hot water. For hot water control you would need the extension unit. If you have the Tado Extension unit then it instead of the Tado Thermostat is wired to the boiler in exactly the same way the Tado Thermostat would be. (But only one of them.) The Tado Thermostat would then communicate wirelessly to the Tado Extension Unit.

  • RayA
    edited October 2020

    Thanks @jelockwood for your advice.

    However, my boiler is in the garage and I was hoping to not have to pull wire into the living room where I'd like the Tado thermostat fitted. From the setup on the Tado app, it seemed that the Tado thermostat could communicate wirelessly with the existing Vaillant receiver on the boiler. Or is that not true?

    I did contact Tado a few days back with this question, mentioning the specific model of my current thermostat (VRT-350f). They only sent back instruction on how and where to physically mount the Tado thermostat, but did not mention anything how to connect it to the receiver wirelessly.

    It is a combo-boiler, so I am guessing the hot water would just get triggered on demand.

  • jelockwood


    There will be an extra cost but a solution for you would be to get the Extension unit and fit that next to the boiler in the garage and link the Tado Thermostat wirelessly from the living room.

    Yes being a combo-boiler the hot water will be on demand.

  • I wonder if somebody here can provide some advice as the Tado customer support is beyond terrible at answering specific questions....

    I have a Vaillant EcoTec Pure 625 connected to a HoneyWell SmartFit (that is completely non-standard and on its last legs), MegaFlow cylinder and external pump.

    I know that I need to replace the SmartFit low power valves- I also seem to have a bit of a 'funky' cylinder thermostat. I need to end up in a position where I can control the heating and hot water. I could just replace the bits, remove the SmartFit controller and install the extension kit, if I do this I am presuming that I will have to use the same 'traditional' method of connecting the extension kit, and that swapping it over to use the eBUS will not work?

    Another option would be a Vaillant VR66 - this would be the ideal as I get all of the functionality of the boiler and I could connect my thermostat straight to it, but my understanding is that the Tado will not communicate with it.

    Any knowledge, advice or suggestions would be welcome - could I use the VR66 in VR65 mode (monozone) or would the Tado Extension kit be better?

    At the moment. as VR66, a Raspberry Pi with eBUSd and a bit of tinkering sounds like it might give me the best of everything, but would be the most complex to implement.

  • jelockwood


    I have not seen an update from Tado regarding Vaillant VR66 compatibility since they confirmed (originally) that they were not compatible with its newer eBus version. I do not believe it is possible to put a VR66 in to VR65 mode but I am not a plumber or expert. It hypothetically would be possible to swap out the VR66 for an older VR65 module with the risk it might invalidate the warranty.

    Note: One would also have to check if your boiler is compatible with a VR65 module.

    A Tado Thermostat and Extension unit should give you heating and hot water but in old fashioned and less efficient 'call for heat' setup regardless of VR66 or VR65 or other. This involves different wiring to the boiler. If the VR66 was supported or you had a VR65 then it would work in newer more efficient 'modulation' control mode.

  • scgf
    scgf ✭✭
    edited November 2020

    For the benefit of those arriving here after a search, I thought I wound mention my situation. It is Nov 2020 and I had a new Vaillant ecoTEC Pro 28 boiler installed yesterday. I had the engineer connect the Tado extension box + and - terminals on the right side of the backplate to the Vailant eBus + and -. I went into the thermostat installer menu and changed it from R01 (relay) to D07 (eBus). He did the usual checks and proclaimed success. As a Vaillant engineer he had been told only Vaillant controllers worked with the Vaillant eBus so he was pleasantly surprised to see it worked.

    Although I have had my Tado system for five years, I had to buy a new extension box a while ago because the relay had failed. The new box already had recent firmware, 71.2.

  • jelockwood


    This is good news! Can you see if you can confirm what version of Vaillant controller module your boiler has fitted? That is VR65 or VR66 or even something else?

  • scgf

    @jelockwood - how do I find out which version my boiler has?