Review on 🔥 SA521CN-3ST Hardwired Wireless Smoke Alarm with Photoelectric Sensor and Battery Backup - FIRST ALERT by Mike Maez

Typical smoke alarm installation. Bought these to replace the original detectors here when we bought this place - they are probably over 20 years old and don't have a backup battery. The only problems were that the wiring from the original detectors was installed incorrectly, requiring a trip to the hardware store for a suitable electrical box (NOT a fan of wires just hanging around!). The only other issue was the age of the batteries that came with these detectors. Couldn't figure out why both devices were chirping. I checked the batteries and they expired on 12/2018 and 9/2019 respectively - a clear indication of how long they have been assembled/packed. No worries, replaced them with new ones - BUT one of them kept chirping even after new batteries. Hm? That's where the First Alert help page comes in - turn off the unit, remove the batteries and hold the test button for 30 seconds to reset the "brains" of the detectors. worked fine Hopefully I'll never, EVER need them to actually work, but as the saying goes "replace batteries every six months" - we've gotten even better and replaced entire units. Now let's add two battery only units to our house for better coverage - and tie them all together.