@croninsfc  OK, I'm not a heating engineer, but having wired up my own Vaillant Ecotec 831 Plus and Tado Smart Wired Thermostat for e-Bus control I thought I'd take a look at your plight.

As far as the wiring goes, references pages 26 and 27 here.…

https://www.manualslib.com/manual/538736/Vaillant-Vrt-392f.html?page=26#manual

It appears that there are just two wires between the boiler and your current wall mounted controller. If your setup is anything like mine it is a simple case of removing the old controller and replacing it with the Tado, reconnecting the e-Bus wires as indicated within the Tado thermostat.

I don't know how the internals of the Tado wireless thermostat differ from my own wired version, but I was given very clear instructions through the Tado app for the swap and the connections.

You should not need to open the boiler at all, but the diagram on page 27 section 5.1 is very familiar from my own experience. Item 1 is the connecting within the thermostat. Item 2 is the connections within the boiler. That should already be in place for you since you are simply swapping an existing thermostat rather than installing from scratch.

Whether there is anything much more complicated to consider I do not know. If you get your hands on a copy of the Tado Professional Installer Manual it should hopefully fill in any remaining blanks.

https://www.tado.com/gb-en/professional-manuals

I do recall having to set a D07 code when completing the Tado setup. Maybe that will apply to you, or maybe D05. I don't recall the ins and outs. It might be something to do with system boilers vs combi. Mine's a combi, which really is super simple to set up (at least with the wired thermostat).

Good luck.

Sounds like a bit of a frustrating experience you’ve had, @croninsfc. I’ve separated this out into a new thread so this specific question (and answer) is easier to find for others affected. I hope that’s OK. 

Keen to hear what you think about what seems to be superb first hand experience advice from @eezytiger. 

I’ll also tag @EverythingNeedsAUserName who might be well placed to help here. After they made a guide on installing their Tado thermostat, here:

Sorry, my boiler controller was covered in the app so I've nothing useful to add. I'm working on an update to my thread after a month's experience with the tado. 

So despite the fact that I have had no prompt from the Tado installation instructions to connect any wires anywhere, I decided to wire a plug to the wireless receiver and at least get the last bit of pairing done. All bits of the starter kit are now paired and apparently talking to each other.

Also I have now managed to get the configuration menu working (now that the smart thermostat is talking to the wireless receiver), and can now find the options for eBus alluded to by @eezytiger - mine being T5 for Vaillant wireless with HW configured for the separate tank as mine is a system boiler.

So back in the Tado app, I can now select my exact current boiler configuration Vaillant ecoTEC plus 600 series + VRT392f (controller and it’s receiver).

Now when I generate installation instructions, it’s prompting me to turn the boiler off

….watch this space

Instructions led me round in circles for a bit asking me about the controller attached to the boiler (I.e the VR 65 which controls the 2 port valves via the ebus), and when I mention VR 65 it says “incompatible”.

so anyway after a few more attempts at describing various configurations of eoTEC plus 600 series boilers (ending with just the boiler itself - not mentioning the connected controller/programmer etc), I got to a point where a request was generated to Tado support to produce step by step instructions for my heating system.

I await the delivery of these by email. Not sure if this is what was supposed to happen!

…and so they tell me “you can’t connect direct to a system boiler, as the boiler must have a controller”,  yes, I tell them - again- it’s a VR65 (which the installation guide says is not compatible- but a Tado forum says it is compatible), so is it or isn’t it, I ask?

Also, playing around with configuration of the thermostat (paired with the powered up and paired receiver via the connected internet bridge), I am trying to save the Vaillant ebus D07 configuration (which I can now select), but the “save” bit says “failed”.

The endless rounds of frustration continue as I await further feedback from tado support having sent them pictures of my boiler/controller and current Vaillant wireless thermostat/programmer set up (which by the way has worked perfectly - if not entirely smart by today’s expectations- for the last 6 years).

I really am wondering why I started this!

Why can’t they just tell me categorically is it compatible or not?
If it is, just tell me which of the wireless receiver terminals do I connect to the ebus terminals to make it work with my Vaillant system boiler?
 

I found this

https://www.tado.com/start/manuals/st/Wireless%20Smart%20Thermostat%20Manual.pdf

which looks like my wireless receiver (and says it’s a V3+ kit), but it shows 12 terminals!
The receiver I have, has 11 terminals, and are not labelled anything like shown on the diagram.

So I wonder what it is exactly that OVO think they are supplying?

@croninsfc  As far as I can tell these are the instructions that match up with what Ovo is offering, with 11 connections and no mention of e-Bus. These are available from the professional installers page.

https://www.tado.com/start/manuals/st/Wireless%20Smart%20Thermostat%20Incl.%20Programmer%20with%20Hot%20Water%20Control%20Manual.pdf

It does look very much to me as if e-Bus and system boilers did not play together with the Tado thermostats/extenders. You can have e-Bus on combi boilers only, like mine.

Mind you, it does seem needlessly confusing, with differing products using similar terms for different components and barely a word about e-Bus compatibility. There is a lot of reading between the lines required and it's a bit of pot luck whether you end up with the product you thought you wanted.

In short it seems to me that it is assumed that relay switching is the default and universally supported connecting method. If you want e-Bus on a system boiler that's not going to happen. If you want e-Bus on a combi boiler then make sure you pick the right Tado product.

Finally an acknowledgment from Tado themselves that the system supplied by OVO will not be able to be connected to my Vaillant system.

Their answer is for me to try and source the older extension kit, which apparently is compatible!
So they want me to spend even more money when I have absolutely no faith in what they tell me any more.

I don’t think so.

I’ll await the results of my complaint to OVO where I have asked for my money back

It’s clearly a minefield then. Reading this entire thread is starting to make me consider whether this topic would make for a really good forum guide idea.

I’d have to think about it for a bit first, as there’s little value in attempting to create a guide if it’s impossible to get the source data from anywhere reliable. Especially if Tado keep changing their products and throwing compatibility all over the place.

Hi @Blastoise186, well the last step in the guide for my dabble into trying to have an OVO Energy smart home ends with the receipt of the returns instruction for the tado!

Explained the situation to OVO via email to smarthome@ovoenergy.com and hopefully will still get the full refund, as it’s impossible not to use the kit to establish compatibility in the first place!

Really hope I can find something that can do what the tado would seem to have been brilliant at if only it had been compatible with my Vaillant heating system.

But not now! I’ve had enough of this for the time being

I’ve passed on the comments you’ve made here to our Smart thermostat team, @croninsfc - as it sounds like the compatibility of the Tado starter kit with your boiler set-up hasn’t been made clear at every step of the purchase/installation journey.

I really appreciate that you’re now seeking a refund and an alternative thermostat solution, so please get in touch if you need any further help with getting the product returned and refunded.

For others considering a Tado thermostat with your type of boiler we’ve had this feedback from the team, you can also check this compatibility guide from Tado themselves:

There may be a previous thermostat which was wired using the ebus connection, providing further boiler efficiency. This is not supported on the Tado starter kit V3 that we currently sell. However, this starter kit can be installed on a Vaillant ecotec 618. The difference is that it should be wired using the traditional on/off relay. If you’re not sure how to do this yourself, we’d recommend getting a local engineer to fit it for you.

After trying the Tado smart thermostat I returned it as it was incompatible with my heating system.

OVO acknowledged that I had cancelled and acknowledged receipt of my returned thermostat.

They even gave a refund for 2 months that had passed from trying the thermostat to returning it.

However, they are still billing me the £10 charge to pay for the thermostat under the heading of “upgrades” despite the fact that I have no upgrades on my account!

Anybody else had this experience of basically being robbed?

Thanks for sharing this on the OVO Forum, @croninsfc - what a pain to still have those ‘Upgrades’ charges applied to your account. 

Can you email the OVO Smart Home team to let them know, and they can get those charges stopped and reversed? Email address to use is: smarthome@ovoenergy.com. If you or anyone else would prefer to call, use our main Support team number and the Smart Home team can be sent the call: 0330 303 5063.

If you go for the email route, feel free to simply link them to this topic to save you having to type anything. It just needs to be from the registered email address so that they can take actions on your account. 

Out of interest, was it the manufacturer of boiler that meant the Tado smart thermostat was incompatible? I can see you posted a similar topic above which outlined your Vaillant ecotec 618…