I think it will be a matter of visually inspecting it. Obviously ideally done by your fitter.
I don't have a Vaillant boiler myself. I did some Googling and found the following link which is (apparently) for a VR66 manual.
The following is for the VR65.
According to a now old response from Tado they were compatible with the VR65 but not the VR66. It could be your boiler has something else altogether.
@jelockwood Thank you, but I am still none the wiser. All I know is that my boiler was sourced by my installer within the last week or so.
I would presume that some on the VR65 or VR66 would indicate which it is, this might be a sticker or printing on the back or inside.
@jelockwood I've been looking through those manuals you sent. To me it looks like the VR 6x is a control unit, similar to the Tado extension box, and is installed on near the boiler. I am now even more confused. I have nothing like this and my Tado extension box is simply wired to the + and - terminals on the eBus inside the boiler.
Thank you for your comments @Ajh. My new boiler fires exactly like the old one did (Vaillant TurboMAX) , much of it due to having comfort mode set, and occasional random firings. The temperature set on my thermostat is being maintained, the schedule works and the home/away mode is reliable, as always. Everything works from my point of view as a user. To be honest that's all I'm bothered about. If the life of the boiler is shortened, so be it. I'll probably have moved house by then. What is the firmware on your extension box?
@Ajh I have the same firmware. I'll leave things as they are and see how it goes long term.
@Ajh Did you go into the thermostat installer menu and change it from R01 (relay mode) to D07 (Vaillant eBus mode)? I noticed that the basic Vaillant user installation instructions do not mention this step, but the professional installer instructions do.
@Ajh My Vaillant engineer warned me that the boiler would do all sorts of strange things for a few days after installation. He said it would be learning about the system to which it is connected. I could imagine there might be situations where Tado and the boiler's onboard computer might be in a minor conflict until it all settles down. Did you allow for this when you connected your Tado? As i said before, I'm happy that from my point of view as a user everything works and my home is always almost exactly at the temperature I have set. The system doesn't under or overshoot in the way it did when I had my old boiler and Todo was in call-for-heat mode.
@RV93 Have you configured the thermostat? It needs to be set to D07 rather than the default of R01. 'D' is for digital interfaces, 'R' for relay interfaces. I have attached the relevant installation manual. The thermostat configuration is the only thing you'll need to do. I have HW x (ie. hot water off) since the ecoTEC Pro is a combi boiler. Running through the thermostat configuration options it should be TS, HC01, HW X, EK ✓, D07.
Only two wires need to be connected. + and - from the Vailant eBUS to + and - on the right side of the Tado extension box backplate. No other connections should be made.
My extension kit firmware is 71.2. Bear in mind there is often an intentional delay after Tado calls for heat until the boiler fires. It could be two minutes or so,
I thought a small update on my experience with an apparent Vaillant-boiler (a Protherm Gepard, CZ model) and the Tado since installed one year and a half ago would be well deserved after venting my frustration on this forum last time.
In short, it works!
It seems as if the water-temperature on the radiators is being modulated after demand, same goes for hot-water temperature. Had a technician over for the annual check-up and he stated that the Czech company's lower ranged products are being build with their own parts, although I do not know how to confirm that without taking the whole boiler apart.
The ability to modulate must have been implemented some time a few months after the installation, either Tado just had to be tweaked locally or the coders twisted and twirled some buttons on their side, I can not know for sure.
Either way, I m still happy with the investment, as long as the system stays online, it has proven reliable and convenient. Apparently, we have have also saved a few bucks when not at home, although 2020 will probably be on the more costly side when it comes to heating.
Only thing that worries me now with this system, is the the lack of any fallback routines if internet fails or if there is some power-outage that disconnects any remote controls.
Glad to hear it is working well for you. It sounds like from your and other comments that the Tado system takes a while - weeks to learn the system adequately.
The Tado will work to some extent without Internet access - obviously remote control stops. You could consider a small UPS. In my own case my longterm plan is to get solar roof tiles and Tesla Powerwall so my entire house can run 'off grid'.
So, to recap, you have the latest firmware on your extension box. You have connected the + and - connections from the Vaillant boiler eBus to the + and - connections on the right side of the extension backplate. Just two wires. You have correctly configured the thermostat (including selecting the tick for 'EK". Everything is shown as 'connected' in the Tado app and the white LED on the extension kit is slowly pulsing.
You manually turn up the thermostat temperature, wait a few minutes and nothing happens? I'm not sure what else to suggest - I did all those things and my System works perfectly.
For information my Vaillant boiler installer was not at all familiar with Tado when he installed my ecoTEC Pro 28 so I did the research and told him how to connect it up. It was a brand new boiler without controls and he just connected the Vaillant eBus to the Extension box using two wires and did nothing else to the electrics in the boiler and once I had configured the thermostat it worked.
@RV93 I'm glad you've got it working. My installer was used to connecting Vaillant controls to the eBus so I suppose he knew about the bridging wire. When he showed me the connections inside the boiler there was a bridging wire in place.
The HW bit is confusing -Tado has no control of hot water on a combi boiler. Ticking HW on the thermostat will give you a Hot Water tile in the Tado app, but it will do nothing. I did HW X and it all works perfectly.