Sharpened, thank you for your response. For clarity, the tado extension kit is effectively a smart two channel controller. Therefore it cannot simply replace my present three channel controller.
My hope is that I can simply ‘short circuited’ my existing first channel, meaning my downstairs...
I have underfloor heating downstairs and radiators upstairs. I also have a hot water storage tank upstairs. The timings associated with the firing of the boiler are managed by a three channel controller (Horstmann ChannelPlus H37).
I have installed tado smart thermostats in each room...
