EMS bus support UK

Montage

The wired Tado thermostats all do modulation.

The wireless EU version of the kit is needed to modulate, aka the EU version. Tado offer this here now.

vmguru

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.

johnnyp78

Tado is good at geolocation and you can link trvs to it. If you don’t need those features, as you said, might as well go for the manufacturer’s controls

GrayDav4276

@vmguru

I don't think that you have missed anything tbh

Les62

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?

Montage

https://uk.shop.tado.com/products/add-on-wireless-receiver-eu-version This wireless unit works. Presumably you have a combi boiler.

Les62

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.

Montage

How will you make sure the flow temps are high enough to create HW?

Les62

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.

Montage

How will the boiler know it’s a call for heat for HW? Tado are very clear that they won’t support SL and bus on the same system.

You should look at Vaillant control centres if you are serious. There are threads on here covering it. I think the one you want is no longer made.

Les62

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

whowantstwoknow

Appreciate the expertise being shared in this thread

The background to my installation was a typical S plan setup with two separate timing controllers (HW+CH) sending via motorized valves switched live to the boiler.

Roll forward 12 months ago whereby I purchased a UK wireless receiver with numerous TVR's for the various rooms. I too have a Worcester Bosch Greenstar 30CDi Classic System boiler and am interested to seeing if I can improve my gas consumption through efficiencies of modulation.

I connected the UK wireless receiver into my S-Plan setup but left the original HW timing as it has a thermostat feedback connected to the side of the cylinder. I couldnt see a simple way of controlling the need to heat the HW with this feedback via the tado setup. ie tado would just seek heat from boiler even if the cylinder was fully heater.

With the current setup the boiler WONT fire unless one of the motorised values are opened.

The Tado pro app suggests my boiler is compatible, with a Digital - HT-Bus (D17).

Q: How do I maintain this level of (motorised values) control going digital? I dont have a bypass to speak of.

Q: going digital, does that instruct the boiler to turn on like the switched live (SL), what about the values?

Q: I assume a tado system should only have 1 receiver, so I'd have to receiver the UK with a EU variant?

Like others, understand the S plan setup but struggling to under the configuration for the digital connection.

Any insights would be much appreciated.

Thanks

W

johnnyp78

Unless Worcester Bosch has done something very advanced, if you’ve got a system boiler you won’t be able to use ‘true’ modulation (but tado will simulate it), if you’ve got a UK wireless receiver it won’t have digital connections anyway so I wouldn’t worry about it.

Even if you bought an eu wireless receiver, unless you can replumb for pdhw I think you’d have the problem of not having hot enough water into your cylinder unless the boiler has some clever circuitry to account for this.

whowantstwoknow

Thanks Johnny

OK, that simplifies my situation greatly!! Confusing when tadio implies it can modulate based on the boiler model. I do see in an electrical diagram from the boiler manual there is reference to "EMS BUS contacts".

Is the limitation on tado or the actual boiler?

Thanks

W

johnnyp78

It’s neither, the problem is having a separate hot water cylinder. On a conventional s/y plan system, modulating the maximum water temp for the heating means that you usually get a lower temperature of water output, resulting in a cylinder full of lukewarm water.

nsteel

I don't want to confuse what is already a very confusing subject (thanks, Tado, thanks Worchester Bosch) but there is some clever WB circuitry to provide modulation support for S/Y-plan systems. It's called the Greenstar Wiring Centre:
https://www.worcester-bosch.co.uk/professional/support/literature/greenstar-wiring-centre-installation-instructions

But before you get too excited, while it does support some system boilers (without an internal diverter valve), it specifically doesn't support CDi Classic System boilers (page 14). I've no idea why.

It seems to be a magic box that connects to some WB Greenstar boilers via EMS bus, and then also connects to all your zone valves etc. There's a little dial to select the DHW temp and it has its own temp sensor rather than use your normal cylinder stat. It has to be used in conjunction with their "Comfort" thermostat/programmer thing that sits within the boiler itself.

I've not tried this thing, the wiring centre and thermostat are pretty expensive. The thermostat itself looks like an antique with functionality to match. And there's a fair bit of rewiring involved. Reading the instructions there also seems to be a few restrictions. It all sounds like a lot of hassle, but maybe that's the price of an efficient WB non-combi setup.

Maybe it's even possible to use the wiring centre alongside Tado's extension kit, both wired to the bus in parallel. But that's a wild guess. If anyone has experience with this setup I'd be very interested to hear your thoughts.