Home Getting started

Installing the extension kit on a Vaillant EcoTech Plus 831

Hi,

How do I wire up the extension kit to a Vaillant EcoTech Plus 831 so that it can use the OpenTherm protocol?

There are no room thermostats connected nor does it have the built in programmer on the boiler.

Have a good Google around and nothing seems to be clear. My boiler has terminals 3 and 4 bridged so that the call to heating is always on, and assume that this is what the extension kit needs to be connected to to switch the heating on and off?

Or should it be wired up to the eBus?

Any help gratefully received 😀

Best Answer

Answers

  • Here is the board schematic of my boiler that I have just found if that helps.


  • @guardianangel

    Vaillant boilers normally come only with eBus unless you are in the Netherlands. In the Netherlands it appears to be a country requirement to support OpenTherm so Vaillant boilers come with a Vaillant VR33 module which converts the boiler to OpenTherm.

    Annoyingly even though this is a genuine Vaillant part if you get it fitted here in the UK even by an official engineer it will invalidate your warranty according to Vaillant.

    Also be warned, Vaillant boilers with the VR66 control module are not supported by Tado as apparently Vaillant changed the eBus protocol compared with the VR65 controller module which Tado does work with.

    I have not yet seen any news from Tado that they have managed to add support for the VR66 controller.

    Worst case you could control the boiler in old/dumb 'call for heat' mode and not eBus or OpenTherm. Another suggestion has been to buy an old VR65 module.

    Personally I am avoiding the problem and intend to buy a Worcester Bosch boiler and use its eBus control.

  • @jelockwood

    Thanks for the info. I specifically asked Tado whether my boiler was compatible with Tado before I bought it and they said yes it was. So it is on them to get this working.

    But you mentioned setting it up for call to heat (which it has the jumper fitted so that is always enabled). How would one setup the Tado extension kit wiring to do that?

    Thanks in advance.

  • @02_london

    Many thanks, I will give it a try and report back.

    Just to clarify, when you say "and dont forget the link wire in 24V RT (boiler side)", that I think equates to pins 7 to 9 according to my diagram above? I don't currently have a jumper on any of those terminals, so do I need to add one, and if so between which ones?

    I also currently have a call for heat jumper between terminals 3 and 4 on the 240v side, do I need to remove that?

  • OK so thanks to the guidance of @02_london I now have this working. On top of the instructions in the PDF he shared above, I needed to do the following:

    1/ There was not currently, nor was it needed, a jumper for the 24V RT on the boiler side.

    2/ The jumper between pins 3 and 4 on the 240V side which I already had fitted needed to remain. This is not shown in the board diagram in my earlier post but is used to permanently enable "call for heat".

    It was just a case of connecting the eBus + and - terminals on both sides. My Extension Kit was already at the right patch / firmware level for this to work.

    Hope this post helps someone in the future.

  • Hi Guardianangel

    Glade you got it working, I suspect you didn't need the 24V RT pins 7 and 8 link wire as you already had the 240V link in place. Link wire keeps the boiler on and our eBUS tells it to turn off to tado requirements.

    Regards James

  • I’ve got a bit of a dilemma on my hands. I bought a Tado on a Black Friday deal in preparation for my new boiler being fitted in the weeks after it, however my local heating engineer who installed my new combi boiler - Valiant Ecotec Plus 832 was unable to get the Tado extension kit working with the boiler via the ebus(they’re all connected to the internet bridge ok). He spent 2 hours trying to get it all working, even going to the lengths to call up a Valiant rep and they done some diagnostics and it came with some ebus error on the screen and a small spanner icon - that’s when they both decided to give up. So now I’m left with a nice new boiler and no thermostat to use with it(resorting to manually turning the boiler on /off and making temperature changes throughout the day), despite Tado claiming to have support. I stumbled across this issue and was hoping someone could give me some pointers with the thin hope that I can have a try at making it all work before sending the Tado kit back in the hopes I can get a refund. Any help you can give me will be much appreciated, I've attached a few pictures below.



  • @dnic

    It could be your issue is the same one I cautioned about to guardianangel.

    Vailllant have apparently changed their eBus protocol with their newer VR66 controller module compared to the VR65 controller module. The Tado system works with the VR65 but not the VR66.

    Your options are as follows.

    1. Find an older VR65 module to replace your VR66 module, I have seen them listed on eBay but you might want to discuss this with your boiler engineer
    2. Get a VR33 module, this translates the eBus commands to OpenTherm commands which Tado also support, the VR33 module is a genuine Vailllant part and fitted as standard to their boilers in the Netherlands but will invalidate a UK warranty despite this
    3. As done by guardianangel configure the boiler to run in 'call for heat' mode

    I still hope that Tado will eventually upgrade their software to add support for the VR66 but this might require them either buying a new one to reverse engineer or Vaillant releasing new documentation. (The later is sadly unlikely I feel.)

    In my own case I plan to get a Worcester Bosch boiler instead. This also uses eBus. The following is a link to a reseller for the VR33 module, they are mainly sold by Netherlands resellers due to their being required in the Netherlands and not supported by Vaillant in other countries. However plenty have people have ignore Vaillant.


  • Looks like you have the correct firmware on your extension kit 64.6 Thats great, now follow the steps below:

    You need to have your Smart Thermostat paired and your extension kit paired with bridge and you can see them in tado app or webpage under SETTINGS | DEVICES - Other Devices (if they are still in setup get tado to move them to Other devices basically informing them all wiring is done, tado will then move them to Other devices.

    1. follow pages 16 to 19 (of the attached) to configure your smart thermostat (use D07 Standard Vaillant eBus )
    2. Then connect vaillant BUS + and - (boiler side) to the + and - on the MAX 36V DC side of extension kit

    There is no need for L and N on extension kit as it gets its power from eBus, jumper link can be set to ether, it doesn't matter which way its round.

    If you need further help leave me a contact number or email and ill get in touch to explan over the phone, Its really simple once you know the procudure of which took me 4 to 5 days with tado support.


    Regards

    James

  • You also could do away with the Extension Kit and just connect the Smart Thermostat MAX 36V DC + and - to boiler BUS + and - as we have combi boilers where hot water is always on.

  • Thank you both very much for your help. I *believe I have it working* using @02_london's instructions above. The only reason I say that is because it seems to take a long time between issuing a command on the mobile phone app and the boiler doing anything about it - is this normal?

    I have a few other technical questions if you don't mind:

    1. Currently I only have + - in the max 36V DC side of the extension kit, is that all I need plugged in there?
    2. I still have the jumpers in Burner off and 24V- RT - do I keep those in there?
    3. The smart thermostat itself seems to have different icons now when I press the button, and I'm not sure what controls what?
  • @dnic @jelockwood

    My installation using eBus works as per the instructions detailed by 02_London further up this thread, but I have an 831 and not an 832, and your circuit board is a different layout.

    However, @dnic looking at your photos, you have the eBus (grey and black wires) wired up to the 240 side on the extension kit which is wrong. You only need to go from the eBus +/- on the boiler to the +/- on the extension kit. This is a low voltage feed that will power the extension kit and also carry the protocol as well. There is no need for the 240v line and neutral feeds. Overall you only need two wires out of the four.

    Just as a side note, if your plumber wired up that extension kit I would never have him in your house again. The line (brown) cable has half the strands hanging out, and if he does not know the difference between a 240v feed and the low voltage eBus feed then he is a chancer. If he had got that wrong the other way around that extension kit would have gone bang.

  • @dnic

    1/ I cant really answer for your boiler as the main board is different to mine, but I had a jumper on the 240v side which permanently enabled the "call to heat" function on the boiler, so when ever I turned up the thermostat dial on the boiler itself, the boiler fires up. This has not been removed, and is needed to enable eBus to fire the boiler when it needs to. In my setup, I only have the +/- wired up on the extension kit (and this will be the same if you wire to the thermostat directly), and this is in turn wired to the eBus +/- on the boiler side. Only two wires are then needed when wiring up the Tado system. You don't need any feeds or wires to/from the 240v side.

    2/ You will find a delay between changing settings on the app and the boiler reacting. Typically this can take about 30 seconds, so it is normal. As long as it is doing what you expect it to do then don't worry about it.

    3/ What icons are you seeing? Can you post up some pictures?

  • @guardianangel

    However, @dniclooking at your photos, you have the eBus (grey and black wires) wired up to the 240 side on the extension kit which is wrong. You only need to go from the eBus +/- on the boiler to the +/- on the extension kit. This is a low voltage feed that will power the extension kit and also carry the protocol as well. There is no need for the 240v line and neutral feeds. Overall you only need two wires out of the four.

    I did notice this, now I have only the grey and black wires going between eBus +/- on the boiler and the MAX 36V DC +/- on the extension kit and removed any other ones that were plugged in and covered them with electrical tape to stop them from coming in to contact with anything else. Thanks for confirming that I did the right thing with this 👍️

    Just as a side note, if your plumber wired up that extension kit I would never have him in your house again. The line (brown) cable has half the strands hanging out, and if he does not know the difference between a 240v feed and the low voltage eBus feed then he is a chancer. If he had got that wrong the other way around that extension kit would have gone bang.

    Your spot on with that one, I came to the same conclusion after he left me without a thermostat, blamed Tado and left the boiler with an error on the display(I think removing the 240v brown and blue wires made the error icon disappear) he's never setting foot in my house again. I'm tidying up this wiring myself!

    I'm still at work, but will give some more info and post some picstures a bit later when I'm home, but in regards to the delay I mean like 10 minutes. My internet is also very good at home(300mbps+) across Google wifi mesh so I can't see that being the issue.

  • All worked ok for me on an 835 which has the same circuit board as @dnic

    I still have the 240v supply running via the extension kit as that it how it was wired but all works ok. Have tested via the thermostat and a TRV and heating comes on each time.

Sign In or Register to comment.