Hi all, please bear with me for my first post. In the attached image is my first attempt at updating a conventional electric hot water/heating system in a flat to a SmartThings system. In the scheme I have shown 2x smart switches but I am completely confused regarding what to buy. The two switches will be controlled by the SmartThing hub and they simply switch existing relays open/closed as per the SmartThing hub. I understand I need a Z wave enabled switch but beyond that, I don’t know what will/will not be compatible with the SmartThing hub. The smart switches carry only a low current, they only switch relays, the relays carry the high current. For clarity, the Siemens programmer shown in the scheme could actually be entirely removed, but for now I am setting it to 24x7 ON to supply the smart switches. Anyone care to recommend smart switches please? Are any available that have a manual bypass switch too in case of network failure? Thank you.