Hi all, I have a flat with immersion heaters in the water tank, one is connected to the economy seven tariff and one is connected to the day time tariff. I'm happy with this, but the flat occupancy is not as regular as I had anticipated so the conventional Siemens time controller, about 13 years old though working fine, could do with upgrading to one I can control remotely from an app. From the research I have done, it seems that the all domestic Siemens time controllers use a common back plate. So, I imagined that I could by a modern WiFi enabled time controller from Siemens, fit it to the existing timer back plate, connect it to the router by WiFi, and voila, app controlled hot water! However, it seems that no such device is available from Siemens. In fact I cannot find a simple electronic heating/hot water controller that is WiFi enabled of any brand. Surely, I'm not asking too much? It's 2017 after all! Any thoughts please for such simple requirements? Thanks.