Help! Stuck mid-install!!!

Hi and Help!

Installing v3+ wireless starter kit. I have replaced the wired thermo as directed with bridging no problem.

I have now got the casing off the Horstman 2 channel H21 XL and reviewed the wiring. The Tado installation guidelines ask if there is 0 / 1 / 2 bridges in place - but I have 3!

The bridges are on terminals:

I thought this was going to be straight forward but now terribly stuck and wondering if I should undo the work I have done?

I’ve contacted Tado support on the app but no response back yet.

Thanks in advance!


  • samd
    samd ✭✭✭

    @damianparker Hello - beyond my knowledge but hope someone here can help. In the meantime you can phone United Kingdom (UK): 020 38932059 and register urgency with no heating. They should treat that as urgent.

  • @damianparker I’m guessing you might have an old boiler that has gravity HW and only the CH is pumped. Meaning the HW must be on whenever the CH is on.

  • Hi - support came back to me. The issue is the bridge between 1&5. It’s been referred and I’ve had to uninstall all the stuff I had done.

    Btw - Don’t believe hot water Is gravity fed - no tank in the roof and my HW tank has a pump on it (wilo gold 50?) The tank is a Albion Mainsflow mf 30/210

    Any thoughts?
  • @damianparker you have a thermal store which explains why pins 3 & 4 are bridged. When the CH is on the water in the thermal store must be hot as it provides the heat to the radiator circuit. The bridging of 3 and 4 forces the HW in the store to heat up. Your current wiring is likely to be:

    1 HW On, connected to Live

    2 HW common, probably connected to thermal store thermostat

    3 HW Off, bridged to CH on

    4 CH On, connected to room thermostat and bridged to HW Off

    5 CH common, connected to Live

    6 CH Off, probably unused

  • Grilled geese

    Thanks - this is sort of correct - thanks for the info on thermal store.

    Only issue with your wiring I can see is that I have terminal 1 &5 bridged - not live and 5.

    I’ll need to get a schematic of the original horstmann controller to match up the terminals to existing wiring.

    Any reason why Tado won’t work with a thermal store?
  • Pin 1 is bridged to Live, which means that pin 5 also bridged to Live.

    The way it works is when the Hot Water is scheduled to be on the programmer connects HW On to HW Common. And when the Hot Water is scheduled to be off the programmer connects HW Off to HW Common. If the CH is on it forces the hot water to be on by making HW Off live.

    I’m sure Tado will have a solution to make this work.

  • HI All - so - Tado have come back and said they are unable to help with wiring my extension kit, I appear to have a strange wiring install in my existing controller.

    Any help appreciated, I have:

    Potterton Suprima 80 Boiler

    Horstmann H21 XL 2 channel controller (HW and CH)

    Albion Mainsflow MF 30/210 Thermostore with a Wilo Gold 50 pump

    Changed and bridged the wired thermostat to wireless no problem but when I got into the controller, the app instructions stated there should be 0, 1 or 2 bridges in place. I have 3 as follows:




    I can't seem to upload photos - keep getting a 500 error on them all. Any ideas appreciated.

  • Did they mention swapping the extension kit for a new wireless receiver? The wireless receiver has six terminals just like your Horstmann controller that perform the same functions, although the terminals are in a different order. I don’t see why this would not work, but you may want to check with Tado before going ahead..

    Tado Wireless Receiver



    Note that CH ON = CH NO, CH OFF = CH NC, HW ON = HW NO, HW OFF = HW NC

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