EMS bus support UK

I think manufacturer controls have upped their game and now providing more feature rich controls than Hive, Tado, Honeywell etc all now provide very good levels of modulation, outside temperature sensor, flow temperature controls, data reporting what does Tado actually bring to the table its just an dumb on or off thermostat? I haven't seen much information on the ebus for the EU model and nothing in the demo app.

Like Ditsy was, I'm in the irritating position of trying to figure out what my system is capable of, and finding that Tado's information is, at best, obtuse. I bought and installed Tado in September 2022 so I am fairly sure I have the bus-disabled UK version. When I download Tado Pro and do a system check, it detects that I using a non-digital connection to my (Vaillant) boiler and recommends that I use a digital connection. There is nothing in the "setup status" to say that my wireless receiver is not capable of handling a digital connection. However, in the physical receiver itself, the connectors labelled A, + and - in the documentation are labelled with an earth symbol and Parking P1 and P2 instead, which rather suggests that I ain't supposed to use them. Is there any certain way to find out (other than trying it)?

If it is not capable of supporting a digital connection, does anyone know if I would need to buy the full EU starter kit (£199.99) including an extra temperature sensor, internet bridge and various other extra bits that I don't need, or will the "Add-on Y plan" (£89.99), allegedly the "latest version", include the bus capability?

Alas not. It's a Y-plan system with HW cylinder, and it looks like the receiver for that doesn't support bus connections.

But I have had another thought. Suppose I put a wired thermostat in my (unheated) utility room where the boiler is and leave that thermostat with a permanently very low set point. I could then presumably use the digital connections on that to do the bus communication with the boiler. Not ideal, unnecessary temperature measurement in my utility room, but I can't see any reason why it wouldn't work.

I'm assuming that the HW flow temperature will continue to be set by the dial on the boiler, and only the CH flow temperature would be overwritten by Tado via the bus connection. Tado's "documentation" implies (but doesn't explicitly state) that it is possible to use multiple wireless and wired thermostats with a system including a hot water cylinder.

Thanks Montage - I hadn't found that clarity from Tado, but I did suspect that there was a flaw in my plan.

Fascinating thread. Thanks everyone for sharing their insight.

I'm interested to see if I can get modulation / digital bus control on my home central heating. I have a Worcester Greenstar 24i System ErP boiler. I have a pretty standard S plan configuration, and a Tado system, with the older extension kit (i.e. it does have digital bus connections - currently not in use). The Tado / Boiler connection is just a simply HW + CH switched live configuration as was installed about 7 years ago by a tado-approved local installer.

My research indicates that my boiler does support ems-bus. In fact, I have very recently hooked up an ems-bus gateway from BBQKees Electronics, running ems-esp firmware (https://emsesp.org/) and I can monitor and log what my boiler is doing on my homeassistant setup (which also integrates with Tado via cloud, and my Octopus energy smart meters). So passively I can see (and log) exactly what my system is up to. I can see from the logs & parameters that the boiler does itself support digital bus modulation commands.

I've not contacted tado support yet, but from what I read the hardware is probably capable of using the digital bus to modulate the boiler, but even if I were to rewire and reconfigure the tado to use digital bus control to modulate my system boiler, I'd be stuck because I would simultaneously need the SL relay outputs from the Tado extension kit to also control the two valves (in the S plan setup) - which I don't think Tado firmware/software supports.

I guess I would probably also need some digital bus temp sensors to take over the role of the existing ones (on the water cylinder, and the frost-stat in the garage), which is all part of the 230v S-plan SL wiring spaghetti (or have some way to have those existing thermostats connect back into boiler or tado inputs in order to retain that piece of closed loop control). Conceptually, hardware-wise I think this is the only missing element, the main issue is lack of Tado software support, as far as I can see.

I may still ask Tado support about this. I think I'd need to capture the current situation in a diagram, to have the best chance of not being fobbed off by my not being specific and detailed enough with my question and situation.

But in the meantime - for those with Worcester Greenstar boilers like mine, who at least want to see and record what's going on with their boiler (even if digital bus tado control is tantalisingly just out of reach), I do recommend the EMS gateways/modules from

https://bbqkees-electronics.nl/

I hope that with some good logging opportunities this winter, I'll be able to get a sense if I would actually get any benefit from modulating anyway.

Keen to see if anyone has cracked a hybrid SL + digital bus operating mode, with Tado + EMS-capable system boiler + traditional Y plan setup yet, My googling efforts so far have lead me to a dead end.