Bests & Worsts Reviews from Amazon

This is a pretty good smoke detector. We ordered six of them to replace increasingly annoying, late-night-chirping, 10 year old units by another manufacturer. We wanted a dual sensor (photoelectric and ionization) detector with 10-year batteries but were unable to find any that fit the bill, and so settled for the 3120B - at least the batteries were AA instead of the more expensive 9 volt. We've had a little trouble with them - the reason for four stars instead of five. First, the battery compartment is hard to open, especially overhead. When you do get it open, it takes a flat screwdriver to pry the batteries out. More importantly, though, the user manual was incomplete. We had an annoying low battery warning (one chirp per minute) on new batteries and a three-month-old unit, but went ahead and replaced them anyway - it didn't stop the chirp. A call to First Alert helped - the CS guy asked if we'd tried a reset, yet. He admitted the procedure wasn't in all of the enclosed manuals. Here's the Reset procedure: remove detector from bracket, disconnect from house power (we needed a flat screwdriver to release plug latch), remove batteries, close battery tray, press and hold test button for 15 seconds, reinstall batteries and close tray (it will chirp), reconnect to house power, reinstall detector in bracket on ceiling or wherever, press Test button to ensure everything's hooked up and functioning. That did fix our "low battery" chirp.