Vaillant VR65 with eBus and system boiler - hot water works but heating doesn't


I've just installed a Vaillant EcoTech Pro 630 (system boiler with two zone valves and a vented HW tank) and have added a second-hand Vaillant VR65 wiring centre as I read on here that this is the way to make the V3 Extension Kit talk to the boiler via eBus.

Has anyone done this successfully and can you tell me how you wired it up please?

I've got the two eBus wires going from the Tado EK to the VR65 and then from there to the eBus connector on the boiler. I have removed the old 240V connection from the EK.

The two zone valves are wired into the VR65 using only live/neutral/earth and without the orange/grey wires that go to the zone valve microswitches. This is as per the wiring diagram for the VR65 (see attached image).

The HW stat is also connected to the VR65.

I have followed the Tado instructions to apply the Vaillant D07 eBus config to via the smart room stat.

When Tado calls for hot water, the boiler fires up as expected.

However, when there is a call for CH, nothing happens.

The only way I can get the CH to run is to apply a jumper link across the RT 24V pins shown in the attached photo of the boiler circuit board, or if I put a 240V live onto the lilac-coloured RT connector. But then the CH runs continuously and doesn't turn off when Tado tells it to.

Several people claim to have got Tado working with Vaillant system boilers over eBus using the VR65 unit, so any ideas on how to do it would be much appreciated please.


  • Hi. I'm also looking at this. My system is a Vaillant EcoTEC 624 system boiler with uniStor water tank VR65 and wired VRC470 on eBus. The CHS and DHW circuits each have a diverter valve.

    1. I contacted TADO support chaps and they said VR65 is not supported. TADO support also made suggestion that the 2 circuits pose a problem for the TADO stat.
    2. My investigations thus far suggest that TADO support is wrong. Folks online do suggest that the VR65's successor VR66 does not support boiler modulation but that VR65 should work.

    I'm looking further at this and compiling a wiring map-over circuit diagram from VR65 to TADO.

    Meanwhile, here is a photo of my current working VR65 if it helps tho' you'd have to guess which cable goes where.

    I'll stay on it - let's get this working.

  • I thought the VR65 would be replaced by the TADO control unit:

    Now, I'm no longer sure if the VR65 has to stay and how that'd be. The diagram above is TADO S-plan wiring diagram.

  • That’s what you’d do if you didn’t want a modulating system - you’d need the vr65 if you wanted modulation rather than relay.
  • You need to bridge the "Rt-24v" if you want the TADO to work with Vaillant (Bulex) through Ebus.

    It took me a lot of effort to make it work in my installation.

    I bridged the "rt-24v" and indeed the system was constantly on and heating on the internal temp control of the heating system... (same way as you would connect a normal on/off thermostat)

    Wiring was correct but the system didn't recognise the eBus thermostat (normally in the service menu of your Heating system you can see if the eBus is detected,(I just had a look in the manual of your CV system, and it's the same parameter as in my system : d90).

    After a while I switched the heating system off and on ... (Tado correctly configured with Id D07). And after the rebooting of the heating system the TADO thermostat detected and was working correctly.

    Now the heating system and also the pump are controlled gradually (not the same Cv system as yours but wiring is quite similar -> Bulex Isotwin condens)

    Only issue I have is that the temperature curve of the system can't be changed anymore (using and external temp sensor on the cv system), these parameters need now to be changed through the ebus Thermostat... but this is not possible in a TADO. (so I will remove the outside temp sensor today)

    Hope this helps

  • Thanks for the replies. I actually got it working yesterday in the end before seeing what you’d all written. I’ll post again later today with details of what I did in case it help anyone else.
  • @autolycus I'm waiting for an extension kit from ebay to arrive to go with the V3+ starter kit, but I have the Ecotec Plus 630, and a VR65 so it'd be great to get a guide on how to install it without having a headache, please!
  • Ok. Here's my solution in case it helps anyone else in the future.

    As an aside.... The solution that @Cliff_in_Auld_Reekie would probably work. However, as someone else said, that's a 240V relay setup where the Tado will simply call for heat but without telling the boiler how much heat it needs - i.e. it won't do modulation. What I wanted to do was to control the boiler via eBus so as the Tado can tell the boiler to reduce the amount of heat being supplied as we get nearer to reaching the target room temp. This makes things more efficient and reduces the risk of overshooting the target temp. Tado can't directly control Vaillant system boilers via eBus, which is why the VR65 needs to sit between the Extension Kit and the boiler.

    So to get eBus working, here's what I had to do.

    1. Apply the Vaillant D07 eBus config to the Smart Thermostat as per the instructions at page 12 of
    2. Connect a 240V L/N/E supply to the Extension Kit. In theory this is not required but I found that the Extension Kit didn't always respond to commands from the app on my phone until I did this.
    3. Connect the +/- eBus (low voltage) connections on the Extension Kit to the eBus connection on the VR65. Also connect the eBus on the VR65 to the eBus on the boiler. And connect the cylinder stat and 2 x zone valves to the VR65 as shown in the diagram and photos in my original post above.
    4. As per my original post, that allowed me to get HW but not heating. To fix that, I had to do the following...
    5. Connect a jumper wire to bridge the two 24 V= RT pins on the boiler circuit board (my boiler came with a jumper for this). Once I did this, the Tado was able to turn on the heating - but only if there was no demand for hot water.
    6. Now go into the installer menu on the boiler. On my one, this involves pressing the top two buttons together and then scrolling down to select the installer menu option and providing the passcode (which is 17).
    7. Once in the installer menu, scroll through to D70 - Set Diverter Valve Position. By default this is set to 0. Change it to 1 (centre position), as this will allow the boiler (via the VR65) to open both the HW zone valve and the CH zone valve at the same time.
    8. Save the setting and exit the menu

    Any questions, just shout.

    Also, if anyone knows an easy way to test if the modulation really is working correctly then please let me know.

  • I've just opened up my boiler and the PCB looks completely different to yours above, and what's in the Vaillant manual 😰

    Trying to figure out where the 24 V= RT pins are. Posting here in case anyone else might have run into this?

  • Just found this PCB wiring diagram which helps understand what I've got going on!

  • What boiler model is that? The PCB looks similar to the design I've seen in other threads on here, such as this one

  • It's an ecotec plus 630 R1. I didn't need to put in a jumper cable on my setup.

    I've now installed my tado setup and all is working fine. I had to set my central heating motorised valve to manual mode, and now it all works great. Thanks for your guide!
  • GazzaH
    edited December 2022

    Hello, so just to confirm, more than one of you has managed to successfully get a working Tado V3 controlling a Vaillant System boiler via a Vaillant VR65 module ebus and you can see and set the heating and hot water temperatures on the Tado app? The Vaillant thermistor connected to the VR65 means that you can see and alter the hot water set-point (temperature) from the boiler and from the Tado app as you would be able to do with vaillant Smart controls? Also I heard that the UK market Tado V3 cannot control opentherm but it can control ebus?


  • Hello all. I’ve got a vaillant ecotec plus 630 system boiler too, and am considering buying a VR65 so I can do all of the above.

    Are any of you guys actual installers? Do you want to come and fit mine? I’m in east London.