When it comes to positioning Motion Sensors it's critical to follow some do’s and dont’s to ensure maximum coverage as well as accurate operation.
The ideal location for a sensor is in the corner of a room. This allows maximum coverage to ensure nothing is missed. Ideally, choke points such as entrances and hallways should be covered and if the Motion Sensor is visible from a window then all the better, a visual deterrent is always a good idea.
The illustration below gives an idea of where to place the sensor:
Finally don’t just concentrate on downstairs for Motion Sensors, think about the upstairs too as a burglar could gain access to the second floor.
So where should you not place a Motion Sensor? You should avoid heat sources such as air heaters and radiators as this will reduce the effectiveness of the sensor. If you’re planning on using a Motion Sensor in the conservatory then again consideration should be given to heat especially in the summer months.
You should also avoid areas where there is steam or moisture such as bathrooms. This will reduce the effectiveness of the sensor and could potentially lead to false alarms.