Add-A-Zone RCO860009 Irrigation Controller is two valves on only one wire: Let Add-A-Zone solve your irrigation problems! Work around broken zone wires and add a new zone without adding new wiring. Add-A-Zone is the proven way to independently control two zone valves with only one pair of field wires. Unlike other “switching” units, the Add-A-Zone behaves just like the valves are fully independent. A patented unit installed at the controller allows use of two separate zones, while sending the signal through only one field wire.