Switch on/off a circuit valve directly with the Extension kit

I have a new Bosch boiler controlled by two Tado smart thermostat and an Extension kit. The ext kit is wired to the boiler and to a relay. When the ext kit switches on the boiler, the relay will be switched on as well. The relay switch on two external Grundfos valve. One is controlling the underfloor heating circuit and the other is controlling a normal radiator circuit. Both of them switch on/off at the same time.

I want to separate this switching since I have two Smart Thermostat (one for UFH and the ither for the rads).

Us it possible somehow to control the two switching with the Extension kit?



  • I'm trying to do something very similar. However, I want to turn on a pump that will send hw to the radiators. The boiler is controlled by the temperature of the water in the tank.

    Have you made any progress?

  • Tamas
    edited April 2

    I contacted with the support but I did not get satisfactory answer....

    Meanwhile I found nearly the same setup explained as mine (No. 2). Except I have one Smart Thermostat on the first floor for the rads.

    I like to control a zone pump (Grundfos Alpha) of UFH with the wired Smart Thermostat. My Extension Kit controls the boiler and another wireless Smart Thermostat is installed on the first floor which controls the rads temperature.

    The Extension Kit is connected with wires as eBUS (digital, with modulation) to my boiler.

    I like to start the pump (wiredly connected Smart Thermostat) and call for heat on the same time (via wireless connection to the Extension Kit). Is it possible?

    If it is possible what configuration do I need on the Smart Thermostat? (D01, R..., etc.) This Smart Thermostat has a wired connection to the Grundfos pump but only wirelessly connecting to the Extension Kit.

    If anyone has any experience or suggestion about it I would really appreciate it.

  • Did you manage to achieve this? I’m
    Trying achieve the same thing
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