Thanks for taking the time to respond.
I am happy to use any type of moisture sensor that will work with the system if I can get the result listed above.
I have been doing a bit of reading and obversly I only need a single rain sensor and the link to underground weather.
So a couple of questions:
could you point me at a the moisture sensor that you were referring to?
And would the senario I described above be able to be done with the RPi version of open sprinkler? Or would I be better to go the actual open sprinkler version.
I would like to know how expandable this system is, as I would end up having to put the lawn sprinklers on the system as the Minster for War and Finance (wife) would expect it could do it.
So I would have to add to the senario above with the lawn sprinklers. (Single valve maybe two)