OK! I’ve installed the Rachio and set up a ghost valve. Works fine but I can’t see how to set it going without setting a duration - with consequent “range anxiety” as they say in the electric car world. So I installed the two-way switch master valve override. Works a treat…but clearly once it’s switched on no-one remembers to switch it off. So what I’m going to do is install a mechanical double throw solenoid switch (cost £5 on Amazon - about $7) which is just like a two way switch except it’s sprung so that the output terminal is normally connected to the NC terminal (Normally closed) except when the solenoid is energized when it switches to NO. NO will be connected to SC, NC to M (as described by Gene) and to energize the coil I have a spare z-wave switch which can be operated either by the local wall switch or through my VERA z-wave controller. I can then include the z-wave switch into the logic which automatically switches off my water features in the late evening so that the master valve reverts to being controlled by Rachio in the evening if it has been overridden during the day.
By the way I checked the SC to C pair with my multimeter and get 27VAC; SP to C gives nothing - good call Gene!
