One of the most frequently asked questions about wireless alarm systems is “where should I install the detectors”.  Before I answer that question, we need to look at the detectors “angle of view”.  Pretty much all detectors have an overhead angle of view of around 90°.

They should be ideally located in the corner of a room or hallway. 

Since PIR detectors view the room in “layers” of fingers, usually 3, and that they are most sensitive to movement across their field of view, they should be located in corner where the expected direction of entry and movement will be across its field of view for maximum catch performance.

Wherever possible aim the detector away from windows, especially north facing windows.  This is not because a PIR detector can see through the glass, but because they can see the glass rapidly heating up and cooling down as clouds move across the sky.  So try to aim the detectors into the centre of the house, away from windows and similar glassed areas.

Another thing to avoid is aiming the detectors at large thermal masses, such as an open fire place, gas heaters etc.  These can actually damage the very sensitive “Pyro-electric Element” inside the detector, and be the source of random false alarms.

Finally, always mount the detector at the manufacturer’s recommended mounting height.  Usually around 2.4m.  This is the height at which the layers of detection fingers are designed to work best, and will give maximum range.  Mounting detectors lower will decrease the range, and mounting them higher will cause "over raging" issues, where the detector cannot lock on the a reference point - leading to false alarms.