The manufacturer said my First Alert smoke and CO Alarms are good for 8 to 10 years. No joke! Two of mine started giving the end-of-life annunciation (5 rapid beeps) at 8 years & 1 month; and within 2 days of each other. Of course, the EOL alert started at 11p.m. Go figure! Anyway, I replaced them.
I have two other brands throughout the house. I'll be ordering replacements soon.
I have two other brands throughout the house. I'll be ordering replacements soon.