Disaster! Warning to others

Following a thumbs-up on compatibility from Tado support via email I purchased a Vaillant ecoTEC plus 637 System Boiler (Tado confirmed the boiler is compatible and would communicate via the bus), along with a Vaillant Unistore cylinder. Subsequently (and now with boiler in situ), via phone today, Tado told me this system boiler was not compatible in bus setup.

This leaves us frustrated, and in a rather expensive pickle. We'd been trying to connect the Tado Extension kit +/- bus connectors through wireless method (TS, HC01, HW yes, EK yes, D07).

Now trying to make the most of what we have. I've asked Tado to escalate their comms issue. The options as I see them are:

  1. Switch the system away from bus to S-Plan, meaning we lose our on modulating boiler and flow rate water control of cylinder, inefficient
  2. Push Tado for refund (doubtful they will play ball as purchased Tado parts through different vendors through ebay and Amazon) and begin setting up a new Vaillant system with Vaillant TRVs
  3. Source an older Vaillant VR65 Control centre (which is now replaced by incompatible VR66) and connect my Tado set up to that (also risk losing Vaillant warranty)

Not all great options, so I'd be very grateful if anyone has any further suggestions.




  • Hi,

    I'm sure you have tried but looking at the boiler circuit board wiring it should be the same as the 800 series. Have a look at this thread and see if it helps at all. Maybe it's the extension kit firmware?


  • rizsher
    edited December 2020
    I currently have

    1) Google Nest controlled my Alpha combi boiler,
    2) 12x Tado Radiator valves on all the radiators that we use frequently and semi frequently, there are 3 radiators which dont have Tado, but these are one in a blue moon use ones that I normally keep switched off
    3) all the kit needed to switch my boiler control over from Nest to Tado as well.

    However, after all the kit got delivered. I am actually thinking it maybe better to keep the boiler control separate from radiator control, i.e boiler by nest and tado by radiators. Reasons being overall heating controlled by the schedule, presence, geo fencing etc provided by Nest, and then, individual radiators controlled by tado... Not putting all eggs in 1 basket, reducing single point failure possibility in probably the one mission critical piece of kit in thr house (well that, and my nintendo switch!!), Giving to much control to one app.

    If the Nest (or Hive or whichever) supports your boiler thru OpenTherm, thereby providing modulation etc, consider it too. The surplus kit you have wouldve cost in the region of 130£, flog it on ebay (you wont lose too much money) and use the proceeds to finance nest or other.
  • Thanks for your help guys. I've managed to resolve my issue by purchasing a VR65. The difference as I understand between the VR65 and VR66 is that the VR66 is multizone compatible allowing for multiple heating zones. As my system is a monozone setup the VR65 works fine. It controls both the HW and CH valves and modulates the heat for both, also talking through the ebus to the Vaillant cylinder. When the cylinder HW is at the right temp it communicates to the VR65 which closes the HW valve (during the timed HW heat period). All works as expected with the system setup described earlier. This setup has been a real pain to implement, partly due to conflicting information from Tado support. But now working as I originally hoped.

  • Hi how did you wire this? I have a VR65 and no idea how to wires the receiver. Please could you help. Thanks
  • I'd love to know as well! I bought a vr65 after reading a number of forum posts like this, and it works but support are insisting it isn't working and I have doubts as to whether it's actually modulating and not just turning it off and on
  • Just a follow-up to this. It is definitely modulating now. I have the older extension kit (with ebus) wired to the vr65 and onto the ecotec 630 boiler all via ebus.

    Hot water control from tado works (just on off timer) and modulation of heating also works. If I had a fancy vaillant tank then the water would also be modulated, as it is the vr65 controls that and requests 80 degrees whilst heating the tank.
  • I've just had a Vaillant EcoTec Plus 630 installed. Having read threads like this one, I had purchased a second hand VR65 unit to go with the above setup.

    I've wired it up as per the wiring diagram that came with the VR65 replacing the optional VRT360/VRC400 with the Tado extension kit.

    The boiler fires up when Tado calls for HW but not when it calls for CH.

    From reading this thread it sounds like at least two people - @Usul and @RonnyJodgers - have got this working. So can you or anyone else share any info on how you wired it up please?