Hi. I see that you can connect up to 4 hose valve/timers to a single hub, but cannot find where to but an extra valve/timer. I hope my search if existing posts did not miss the answer to this. I’m new 
On the page Automate your watering with Rachio Smart Hose Timer | Rachio, it asks “A Smart Hose Timer valve requires a WiFi Hub and can support up to four valves. Do you need a WiFi Hub?” followed by a YES and NO buttons. If you click NO, it looks like valve/timer without the hub.