Hello Pak0,
what do you want to control? A signal from Open-Therm to Vitodens 200?
In Canada and USA there are KM BUS and Open Therm connections. That's an extension kit for heating circuit with mixing valve. But only for main power supply 120V
Kind regards °pa
For example you can use Viessmann Vitocomfort. >> http://www.viessmann.co.uk/en/residential-buildings/heating-systems-for-new-build/smart-home-system....