The nature of a PIR motion sensor’s field is such that they can’t cover an entire large room. They detect very small changes in heat moving across the sensor’s field. They will be better at detecting things moving across that field rather than straight towards them, so placement makes a big difference as well. Most have the same range of about 10 m, but it’s a cone-shaped field where the detection area is wider farther away from the sensor.
If you want to cover a large room or multiple entrances, you can set up two or three sensors in a zone. Mike Maxwell has a popular smartapp that can manage this very effectively.
If you haven’t used custom code with smartthings before, take a look at the following overview FAQ.
And if it seems like something you’d like to continue with, here’s the thread to Mike’s code:
