Firstly, check that the green LED on the face of the alarm is illuminated. This means that mains power is connected.

Press and hold the Test button on the face of the alarm for two seconds. The alarm will sound 3 short chirps, pause for 1.5 seconds, and then continue sounding until you release the button. This confirms the alarm is working.

If your alarms are hardwired interconnected, test each unit individually. While holding the Test button, the triggered alarm will sound, and any interconnected alarms should also activate. Have someone check all other alarms are sounding while this button is pressed.

After testing, ensure the red LED on each alarm is flashing. This will continue for approximately three minutes, indicating the test was successful.

Isolate the mains power by pushing the button on the side of the alarm to detach the head from the base and have it swing down from the ceiling.

Remove the backup battery.

Press and hold the Test button for 15 seconds to discharge any residual or stored power in the unit.

Repeat these on all hardwired interconnected alarms before replacing batteries or reattaching head units to the bases.

Insert fresh backup batteries, then swing each head unit back up and secure it onto its base until it clicks into place.

A single chirp accompanied by a red LED flash every 48 seconds indicates the backup battery needs replacing. This alert cannot be silenced until the battery is changed.

Press the Push button on the side of the alarm to release it from its base. Open the alarm body and replace the backup battery with a new one.

Close the alarm body securely, then refit the unit onto its base until it clicks into place.

When the alarm reaches the end of its service life, it will emit one chirp with two red LED flashes every 48 seconds.

This signal means the entire unit must be replaced. You can also confirm this by checking the printed expiry date on the back of the alarm.