OK So I know they are designed to save our lives, but I have just had a fire alarm related hysterical breakdown. Our fire alarm started cheeping a few weeks ago, so we duly replaced the battery. It continued to cheep, randomly every few hours...so we replaced the battery again presuming it was a dud battery. It continued to cheep. And cheep. And CHEEP. So. Today I bit the bullet and bought a brand new fire alarm, affixed to the ceiling, new battery that came with it...job done, no more cheeping. And then... IT CONTINUED TO CHEEP! I read the manual from cover to cover. I emailed the manufacturer. And then, casually thrown into conversation, my OH mentions the fact that we "Do have a second fire alarm on the upstairs landing you know." NO. I DIDN'T BL**DY KNOW. New battery installed, chirping fixed.