Vaillant Green iQ ecoTec Boiler

Has anyone tried to use Tado with this boiler. I am not clear on whether doing so will mess up the performance of such a boiler which uses outside air temp and analysis of performance at Vaillants own servers to adjust the startup time to achieve maximum efficiency. I would appreciate any comments on this . Thanks


  • @Nidge

    I am not an expert on boilers or Vaillant but in general they use the eBus protocol. Vaillant boilers fitted with the VR-65 controller module are supported by Tado in that Tado understands the eBus 'dialect' spoken by the VR-65.

    However the VR-65 has been superseded by the VR-66 and Tado have not yet decoded the eBus dialect spoken by that version.

    It is possible to wire the Tado to a Vaillant fitted with a VR-66 in the old style 'call for heat' configuration. This however loses all the smartness that eBus could otherwise provide.

    Some probably many makes of boilers have the option of something called a 'weather compensator'.

    This is not the same thing as a fullblown eBus (or OpenTherm) smart thermostat but can enable the 'modulated' heating control that is a feature of eBus and OpenTherm. (It would conflict with a smart thermostat trying to do this.)

    It is not clear if what you are describing is along the lines of a weather compensator or might be a half way house solution along with a Tado in 'call for heat' mode.

    I suggest you raise a support ticket with Tado with the specific model details for advice.

  • I've been running a Vaillant Ecotech+ 424 and Tado for 4 years, does most of what i want but not all, there are limitations Tado don't seem keen to help with. Efficiency is mostly about modulation and keeping the flowing return temp as low as you can get away with but hot enough to sterilise hot water at 55 deg C. I set my flow temp on the boiler panel at 60 deg C and scrap the early start up nonsense and just start / stop on tado timers or phone locations. Look at figure 1 in this below and this is where Tado could help all its customers by using this intelligently. Not sure how it would interface with green IQ, looks like a Tado look alike.

  • Thank you both, for sharing your respective experiences and opinions. Clearly there is complexity here that I had not anticipated.

    I only changed to tado today, so may be back on line soon as already there seem to be indications that I may have not gained anything .....

  • Did you manage to get your setup to work as expected? The Green IQ is a combi in the UK, however possibly in other parts of the world a regular too.

    If it's a combi boiler in a standard setup (no underfloor or relays) then the Tado just replaces the Vaillant controls and the outside temp sensor.

    I have an EcoTec 938 and have wired the Tado to Vaillant 938 via eBUS. Vaillant say that they would void warranty for Tado using eBUS, however I'd happily take them on with this if they tried.

    I find that Tado modulates the flow temperature, however I feel it does it too big a steps causing the boiler to go in to anti cycle as the return temperature is then exceeds the requested temp. It would make more sense to go down 1 degree at a time.

    Hot water also works however Tado is able to override the lower safety temperature for my built in tank allowing 35oC and not the minmum that should be 50oC.

  • I've just installed a Tado Wireless Receiver and TRVs into a system with Vaillant EcoTec Green IQ 627 (not a combi). Will see how it goes for a week or so before adding the 4 wet underfloor heating zones to Tado too (with wired thermostats).