Ok, software done; on to the relay controller box! [danman]’s sprinkler system has four 12V AC valves that need wrangling, and no data cables, necessitating the wireless setup.

These G9TA relays feature 2mΩ contact resistance, 6kV impulse withstand voltage, 250Vac max switching voltage, and 12Vdc coil voltage. The 120A (276Vac, or 100A with PF=0.5 inductive load) G9TB AC ...