If social service robots are to be successful in becoming part of our everyday life, they need to have proper signaling of their intention to be predictable. This is especially important when interacting with elderly people, who might be less acceptive of technology. In this study we report on such a device, a plant watering robot (PWR) for elderly care centers, which has social signaling capabilities. Signaling is achieved by using a social agent (myKeepOn) and a steerable propeller/fan on the deck of a ship-like mobile robot. We conducted an online survey to assess how predictable the robot’s behavior is. We have found that the social agent was very effective in conveying turning intentions of the robot, while the propeller was less able to do so. When signals from the two sources collide in meaning, people were not as confused as expected, and prediction rates kept steady.