Do I need to use the Watts Sensor Valve Kit with this pump?

The Pump comes with one sensor valve that definitely needs to be used in order for the system to work properly. An additional Watts Sensor Valve Kit would only be needed if additional sensor valves are needed. (Typically a two story home or a larger home that would have bathrooms on separate sides of the home)

Yes that's how this operates as a recirc pump. It's simple just connect to the furtherst sink away from the water heater. Works like a charm. Has saved me hundreds of gallons water. I used to dump approx 3 gallons of water before I would get Luke warm water now it's like a cup.