Carbon Monoxide Alarm

[Alex]

Incase I'm not the only one who didn't know this 
My alarm has been sat on a shelf for 10 years, the little green light blinks reassuringly every few seconds.  As far as I knew that meant it was still working, but maybe it's reached retirement age as apparently you need to change your CMA after 7 - 10 years, depending on the model.   If it needs changing it will beep every so often, or digital models will show Err for error.

Looking at mine it says on the back to replace after 7 years.