My alarm keeps sound every 15 minutes I keep having to press the hush button to stop it also I have noticed that there is no green light present compared to a second one I have upstairs. My understanding is this may be an AC connection problem or a battery problem. How can I fix this otherwise this will go on all night.

Hi Neil

Check 1 - is the fuse in the electricity cupboard flicked off?

Check 2 - is the green light coming on if the light switch is flicked on in that room? If so, the unit is incorrectly wired. It should be connected to the 'always on' wires if it is indeed powered by lighting circuit in the first place.

Check 3 - Is the 4985 unit older than ten years? If so, it needs replacing with a new Kidde Firex smoke alarm

To check the date remove the alarm off the ceiling watch the removal video

If check one to three are all ok, it's time to get an electrician to check your power supply.

Harry