Bring back Modulation (OpenTherm) to their wireless thermostat (UK)



  • Hi, lots of info here apologises, but just wondered…

    Our combo boiler is on its way out so looking to get a replacement fitted. Seems the Worcester boilers don’t do opentherm so looking at getting an Ideal vogue max 32.

    Another issue is my tado wireless receiver is a few years old and I double checked and doesn’t have the opentherm wiring at the end.

    So I’m guessing I need to buy:

    And do a swap ?

    Is opentherm all that great, will I effectively save £90 on heating ??

  • If you are considering a new boiler and are aware of the benefits of opentherm then are you planning on running just a couple of radiators? The boiler you have mentioned does have an okay minimum rate of 4.9kw @ 40oC, however you can get boilers that can turn down even lower if like me you only want to run one or two rads.

  • Oh thanks for the info, any suggestions I should consider ?

  • johnnyp78
    Ideal vogues are decent boilers and work well with opentherm. I speak from experience. Not sure what the difference between a vogue and vogue max is though
  • @johnnyp78 Theres no difference Fella, bar the max comes with a filter which gets you another few years warranty. Insides are the same
  • Well I joined here looking for an answer as I was just about to go and buy a Tado as customers ( yes I’m an installer ) had raved about them.
    And I turn up and find a forward thinking company isn’t that forward for the UK market :(
    Guess this daft installer will have to fit an ESI for opentherm..
    After all two wires and non voltage carrying lots of zero’s and 1’s is a major mind blowing experience after fitting 20 plus wires in a s-plan plus systems for 20years
  • @GasMan42

    What specifically is stopping you? Is it just the lack of S plan support?

  • @robkarloff

    Thanks for your suggestions.
    So to summarise, if I have a S-Plan and I convert it to a DPHW/X-Plan then I can but a wired thermostat and connect it to the PDHW boiler with OT assuming I configure the app to use the new wired thermostat as the new controller. This makes sense.

    Just one question. Can I keep/use my "old" V3+ wireless controller to enable/disable the hot water as I currently the the V3+ controller driving my S-Plan where I have both the heating and hot water relays wires connected?

  • johnnyp78
    I’m not overly familiar with x plan/pdhw but I would have thought for hot water control you’ll still need a wireless receiver. You should be able configure that as one zone controller for hot water and the wired thermostat as the other zone controller for heating.
  • DNC

    I have a system with 2 x wired tado stats and 1 wireless stat and i am having a new Intergas combi installed which has opentherm. Do i just connect the - and + terminals from my wired themostat to the intergas opentherm connections or is it more complicated than that.

    Any advice or suggestions would be appreciated.

  • johnnyp78
    Doesn’t intergas have dual Opentherm connections? In theory you could connect each wired thermostat to an opentherm terminal in the boiler but I have no idea if Tado is able to cope with that.
  • KTF

    Apologies for the thread bump but I am struggling to get an answer from Tado support for this question.

    I currently have a v1 wired stat and a glow worm heat only boiler that supports eBus. I would like to get modulation via eBus and hot water control which would need one of the original extension kit. I would need an original one as I have a v1 stat and also that the original ones came with modulation and eBus support.

    On ebay I can see what looks like several original extension kits listed. One has the part number EK01-TC-UK-03 and the other EK01-TC-ML-01/UEK01-TX-02 Thermostat Receiver Extension Kit (DBU01-TA-02).

    Tado support only pointed me in the direction of their current v3+ offerings and would not confirm if the above would achieve what I want.

    As the knowledge here is much better than Tado support, can anyone tell me if the model numbers above will work with my v1 wired stat and achieve modulation via eBus?

  • @KTF if your current thermostat is genuinely V1 hardware then it won't be compatible with the latest hardware. V2 and V3 are interchangeable, but they use a different technology to V1.

  • KTF

    Good point. I checked my shopping history and it is actually a v2 stat with the more chunky version of the bridge:

    The v1 is a very different beast as you say.

    Whilst my stat has the +/- to allow digital control, there is no wiring in place for that nor have I any idea where the wiring for the stat in the hall goes through the house to get to the boiler (assume up then under the first floor and back down to the boiler in the kitchen.

    This is why I was looking at one of the earlier extension kits to add to my setup as I could then have the +/- on that wired to the boiler and the stat sends the information to it via the bridge.

  • @KTF in that case you have the option to use any V2 Extension Kit, or a V3 Wireless Receiver with EU specification.

    BUT I note that you have a Glow Worm heat only boiler. Tado digital bus interface is designed for Combi boilers. If you have a hot water cylinder then you cannot easily use eBus. The setup for a hot water cylinder relies on motorised valves controlled with 230V. The low voltage eBus won't be able to control these valves.

  • KTF

    I do have a heat only boiler and cylinder.

    My understanding (correct me if I am wrong) was that the programmer (Potterton EP2) deals with the opening and closing of the valves depending on what is being demanded and then sends the call for heat to the boiler.

    I thought that as the extension kit is a replacement for the programmer then that would also deal with the opening and closing of the valves? But with the addition of eBus to the boiler it would be able to send some 'intelligence' via the data from the smart stat/bridge to modulate the flow, etc.

    Is that not the case then?

  • No, the EP2 programmer supplies power to the room and cylinder thermostats at the programmed times. For example, if you program the central heating to come on at 7am, then the programmer will supply 230V to the room thermostat at that time. If the temperature in the room is below the target setting, then the room thermostat will supply 230V to the motorised valve. On the receiving power the motorised valve moves to the open position and then supplies 230V to the boiler's switched live input.

    The Extension Kit can do low voltage eBus or 230V relay output, it cannot do both at the same time. Glow Worm have a device called a Smart Wiring Centre that takes an eBus input from a thermostat and operates the motorised valves, but the device is no longer compatible with Tado. They used to be, but Glow Worm (Vaillant) changed the bus protocol so it is no longer compatible with thermostats made by other manufacturers. They (and other boiler brands) want to lock homeowners in to their expensive proprietary controls.

  • KTF

    Thanks for the extra information and sorry for the delay in replying.

    That pretty much scuppers what I had in mind from the extension kit as I thought it would be a one stop shop like the smart wiring centre was. I didnt realise it was either digital control or relay and not both.

    I can live without hot water control and really want the flow control but it sounds like I would lose the ability to control the hot water (even on a basic level) should I wire the extension kit up for ebus which is a shame.