Door Sensor Installation
Door Sensor Installation Tips
These sensors can be tricky to install because the magnet on the sensor needs to line up with the magnet in the contact. Before deploying to a client's home, it's a good idea to apply sticker dots to the contact and to the spot on the sensor that should match up. That way, if the sensor or contact ever needs to be remounted, it will be obvious to the customer which way it goes.
To determine the location of the battery inside the sensor, you may need to open the cover of the sensor and have a look. You should see a small glass tube. That's the magnetic switch that should be facing the magnet on the door.