Issues with eBUS (Vaillant) support and Tado X

Jeff_

Hello everyone,

I recently upgraded to the Tado X Wireless Thermostat, but I'm facing some issues with my Vaillant ecotec plus (vcw296) boiler. This boiler uses the Vaillant eBus protocol. My previous Tado V3 model supported modulation via eBus, but after connecting the new Tado X in the same way, it doesn't seem to work.

According to the documentation, I should use the relay on/off, which means I would lose modulation. Am I missing a setting, or does the Tado X not support eBus? If eBus is not supported, this new version is completely useless for me. Is there an update in the pipeline to support eBus?

Any help or insights would be greatly appreciated!

Thank you!

Hansolo

TADO X is only compatible with Opentherm or dry contact relays

Kissarmy

I recently ordered the VR33 module from Hartog in the Netherlands - where all boilers have to talk opentherm so Vaillant had to make an add on board to be able to sell boilers

https://www.cvonderdelenhartog.nl/Vaillant-VR33-OpenTherm-module-0020017895/en

This is the cheapest place I could find that ships to UK. Arrived quickly with no extra customs charges. About £73 delivered.
This turns opentherm commands into ebus commands.
Do be aware that Vaillant are a bunch of money grabbing ....ers who only want you to buy their controls so adding this to your boiler will invalidate your warranty. My boiler is out of warranty anyway.
If you are in warranty and have any problems and need Vaillant engineers to come out and sort a problem remove the module an rewire back to relay mode before they fix it.

olly2009

My boiler is out of warranty as it is 5 years old. Did you find documentation of how to wire the wireless X receiver with VR33. Receiver has +/- connectors and VR33 a OT/ground connector. Can you control hot water boiling?

Kissarmy

This is a pic I made to help somebody else, Your boiler won't have the wire for the actostor water tanks as that is unique to the 937 combi boiler which has an add on section behind it containing a small 20 litre storage tank. The rest of the wiring is the same. The colours of the wires on the opentherm connector are the wrong way round but they match how the bus connections in the Tado extension kit I have were wired - I should really have changed both ends. It is + to OT and - to ground.

Having a combi boiler I don't need the HW control. I think from other posts I have seen on here that X does not do hot water using opentherm at the moment. Hopefully somebody else can hehelp with this info.

olly2009

@Kissarmy thanks a lot. I will try this. Your schema aligns with my understanding the only part missing was the wiring between VR33/Wireless Receiver/

BeoVision

Thanks for the useful info, I'm about to invest in X which will replace a nest system. Initially I'm thinking of installing in relay mode but am aware that I can use the VR33 on my ecofit pure 835 boiler for modulation, would you say it's worth it overall?

@olly2009 - Did you manage to get it all working?

BeoVision

I've just had a look at the board In my boiler and there does not appear to be an X31 edge connector, does that mean I cannot use the V33 module as my boiler does have ebus terminals so thought it was possible

olly2009

Sorry to hear that. I am only running with the valves for the moment using the original thermostat. I have yet to install the VR33 and the wireless receiver. But I’ll do that in couple of weeks.

Kissarmy

Strange, I've looked at your manual and correct, no x31 edge connector. I have also looked on Vaillants .NL site and checked the manuals for a couple of slightly different ecoFIT models that are available in the Netherlands. The PCB appears to be the same as the PCB in your manual. The website clearly states that it is possible to use the ecoFIT boilers they sell there with the VR33 for Opentherm control. I'm guessing there must be either a different cable to go from the X31 on the VR33 to a different connector on the PCB or a way of connecting the wires to the terminals rather than using the edge connector. 2 of the wires going directly to the ebus +/- makes complete sense but the other connection I don't know. I have not managed to find any other info yet.

BeoVision

Thanks for the feedback, really appreciated! If you don't mind seeing if it's possible then that would be great as I really would like to get the system setup using modulation.

I just found this online where somebody mentions connecting the VR33 to x32 on the pcb which mine does have, is there a way to verify that this is ok to do so?

https://automatedhome.com/vbulletin/forum/general/heating-control/6579-vaillant-ecofit-pure-435-evohome-opentherm

Kissarmy

Looking at the manual for the 435 the PCB appears identical to yours.

I found this link - read all the comments

https://www.reddit.com/r/Nest/comments/ia7i4s/vaillant_vr33_opentherm_module_for_nest_heat_link/

Obviously this doesn't verify it but adds to the circumstantial evidence pointing that way.

Kissarmy

I've just gone back and looked at the VR33 manual and realised that it has X31 and X32 connectors. The Actostore hot water storage module at the back of my 937 was plugged into the X31 connector on my PCB. Looking at a photo when I added my VR33 I moved the Actostore connection to the X31 connector on the VR33 and I used the supplied cable from the X31 connector on the PCB to the X32 connector on the VR33.

In.my case it seems like the X31 and X32 connectors on the VR33 are interchangeable and act as passthroughs. The other comments read like X32 is a newer version though I have no idea what difference there may be.

Kissarmy

Another thing to add, if you check your boiler diagnostics D.090 will tell you if your boiler can see an ebus controller - in this case if it sees the VR33.
Checking system status with the Tado Pro app would show if there is a good opentherm connection to the VR33.

BeoVision

Thanks again, it does look like its possible reading the comments, I suppose the only way to truly verify is to order the kit and give it a try. In terms of the diagnostics on the boiler am I correct in thinking that i would need the VR33 connected before i am able to test? Currently my PCB does not have a jumper lead on "24=RT", I take it I would need to do this? Also, the cable that connect to the OpenTherm terminals on the V33, do I use the cable that is supplied with the Tado wireless receiver that also connects to the power on the PCB?

olly2009

You would need to shortcut the 24 rt to act as always on.

Kissarmy

My Tado X order arrived today - all the SRTs, wireless sensors a d bridges - but not the "wireless starter kit inc programmer with hot water control" so I don't know what cable is supplied with the wireless receiver.
Without an ebus connection D.090 would show 0: unconnected. If you get the VR33 connected and working it will change to 1: connected.
The jumper on 24V=RT put the boiler into heat on mode as it thinks there is a thermostat connected that is calling for heat. The ebus signal then blocks that heat call until it wants heat.

BeoVision

Thanks again for the feedback guys, really appreciated! I'm going to order all the kit and give it a go and let you know the outcome. One last question, how do I initiate diagnostics on the boiler?

Kissarmy

This link is to a rather generic Ecotec Plus installation manual. Its not specifically for your model - the only manual I could find for yours was in Dutch and only the operators one. I expect all Vailant combi boilers have similar menu structures, difference seems to be some have displays that have a lot more writing on and some are very simple - just a few digits of info.
Check out page 38 which shows how to access the installer mode and get to the diagnostics. Some of the diagnostic codes allow changes to be made, I would strongly suggest not making any changes here. I purely use the diagnostic codes to check that things are working - for example checking that the boiler recognises an attached wbus controller such as the VR33.

https://www.plumbnation.co.uk/documents/vaillant-ecotec-plus-installation-maintenance-guide.pdf?srsltid=AfmBOopQfqO43P_CYgPK1l4yS8ZpU8YwG2wloV3gPo5EVbXgG1dBrRYZ

BeoVision

Nice 1, will let you all know how i get on.