New Tado. Central Heating working. Hot Water not working. Can anyone help, please?


I have a new Tado that I want to use to control our central heating and our hot water. My kit is a smart thermostat, receiver, and a bunch of smart radiator thermostats. It was installed by a professional gas engineer. It was installed yesterday.

The central heating is working fine however the hot water is not working at all. My problem solving:

  • When I make actions in the app, the Tado Thermostat reflects the change. So if two independent devices are updating, the software is working correctly, I think(?).
  • The Tado app can control the central heating. For example, if I boost the rooms, the Central heating light comes on the receiver and if I turn off the central heating, the light goes off. Therefore, the wiring for the central heating must be correct.
  • However I can't find a way to get the Hot Water light on the receiver to come on. If I click in the App or on the smart thermostat, it has no impact. So... I guess this is a hardware issue with the Hot Water? Either the writing? Or the boiler? Or something?

I've found some other threads where people talk about Y systems and combi systems but I do know what these mean. Our boiler is a Vaillant Ecotec Plus 838 if that helps, and this is a picture of the current wiring:

Has anyone else had this problem and do they know how to fix it?



Best Answer

  • knockoff
    Answer ✓

    Hi Everyone,

    I managed to get the engineer to come around today. He turned it all off and on again (I did not know there was a power switch to do this) and it started working.

    Thank you all for your input, I appreciate the community effort.

    Just in case anyone wants to know, I asked the engineer what you have all questioned me. His response was that despite having a combi boiler, our house also has a water tank (what I assume you are calling a 'system boiler'). The engineer cannot explain why, although I will say it isn't the only odd thing about the way this house was renovated by the previous owners. Regardless, our hot water is coming from the tank.

    Thanks again,



  • Do you have a combi or a system boiler? Could you provide a picture of your previous set up.

  • Hi @royi thanks for the quick response.

    To your first questions: I think it is a Combi boiler. I think this is a link to the Vaillant Ecotec Plus 838 model details.

    To your second question: This is what it looked like before. According for the engineer who installed the Tado, the Drayton thing was the primary controller, and the white block above it was a secondary controller that transmitted to our old thermostat.

  • Montage
    Montage ✭✭✭

    If it’s a Combi boiler, why do you want to switch DHW using Tado?

  • johnnyp78
    johnnyp78 ✭✭✭
    Pretty certain that’s wired for a system boiler. Can you post a clearer picture of the wiring?
  • gary333
    gary333 ✭✭✭
    edited January 23

    Do you have a hot water tank? If not, no idea why they have wired the hot water in, it's not needed as the hot water is controlled by turning the tap on (and the control panel for hot water temperature). I can control my water temperature via the eBUS digital link), but via relay like your setup you cannot control the hot water temperature within the app (so the button should be hidden in the app if the right settings were selected by the installer). Would seem strange using such an expensive boiler as a system boiler rather than a combi, as you're paying the money here for the combi bit.

  • Your system (old wiring) is a Drayton with 2 channels. CH & HW. The CH wiring has been removed & rewired to your old wireless stat. The Drayton controls your HW. There are two types of wiring, S plan & Y plan. How many valves does your system have? I have two valves & that is S plan. If you have one valve with three ports it’s Y plan ie 3 copper pipes. This basically can switch between hot water from the boiler or it can send it to the radiators . I also have a hot water cylinder which is pressurised & has an expansion tank that looks like a metal large kinder egg. Get your electrician to look an YouTube & subscribe to @Plumberparts. This guy explains step by step how to wire in a boiler from scratch & even recommends a replacement wiring center that is the dogs nuts & very easy to wire up. ( Yours is like mine a Honeywell). S plan & Y plan explained too.