First Alert 9120b Review

Here is complete guidance about First Alert 9120b Review. With the First Alert 9120B Hardwired Smoke Alarm with Battery Backup, you can make your home safer. This 120-volt AC smoke detector detects smoke from hot, fast-flaming flames using an ionization smoke sensor and informs you with a loud 85-decibel siren.

This hardwired smoke detector is designed to be hooked directly into your home’s electrical system and has a backup battery to keep the alarm working even if the power goes out. The gasket-less mount ensures perfect alignment for quick installation, and tamper-resistant locking pins secure the notice.

You can also check whether the alarm is working correctly and stop false alarms using the handy test/silent button. This smoke alarm can work with up to 12 other First Alert or BRK hardwired alarms, and it has a latching indication that lets you know which one triggered the alert.

First Alert 9120b

First Alert 9120b Review : Advantages & Disadvantages


  • This hardwired smoke alarm will keep your family safe. Even if there is a power outage, the battery backup allows for continuous monitoring.
  • This smoke alarm, which has an ionization sensor, effectively detects smoke from fast-flaming flames and sounds an 85-decibel alarm.
  • Place one on the bottom of your home and in each bedroom to ensure comprehensive protection.
  • When smoke is detected, it can be connected to other compatible BRK or first alert smoke detectors to ensure all alarms sound.
  • With a single test/silence button, tamper-resistant locking brackets, and universal mounting brackets on the side of the battery compartment, installation is simple.
  • To ensure that it meets UL standards, it has been rigorously tested.
  • The alarm is powered by 120 volt AC with a 9-volt battery backup to keep it running during a power outage.
  • Since establishing the first residential smoke alarm in 1958, First Alert has been the most trusted name in home safety (Based on a First Alert Brand Trust Survey in February 2018)
  • Faster job site turnaround with the easiest-to-install, most-trusted home security alarms


They are susceptible, so even if I generate a small quantity of smoke on the stove or in the oven, the entire house would scream. It’s nearly impossible to tell which unit has a low battery because they all seem to sound seldom (really). The fact that they are hardwired has both positive and negative implications. This is fantastic if there is an actual alarm since they will all sound.

An Honest Review

I bought a couple of them three years ago to replace my outdated detectors. When it came time to replace the batteries, I hoped they wouldn’t cause me any problems; the old ones were a touch picky and would still chirp even with brand-new cells.

One of them began chirping around midnight this morning, despite its battery reading of 9.62 volts. I replaced the battery, and I checked the battery’s voltage in my other detector, which was still working great, first thing this morning, and it was 9.23V. After doing some research, I discovered that a chirping smoke alarm might require a hard reset to clear the microprocessor of flaws that could result in a false low-battery indication.

Turn off the power, remove the battery, and then press and hold the test button for 15 seconds (it’s also an excellent idea to silence the siren by covering it with your thumb.) The alert will sound, then fade away to silence.

I plugged the problematic unit back in, installed the 9.23V battery, and it’s been operating great for many hours- so if you’re experiencing trouble with an alarm that still chirps every few minutes even when the battery is good, a hard reset might be the answer.


The First Alert 9120b is one of the top dual-sensor, battery-powered detectors in our ratings, with good scores in both the burning and smoldering fire tests. It has a push-button and is powered by two AA batteries, but it can’t communicate with other alarms to make them all sound in the event of a fire. That’s all I have on First Alert 9120b Review.

Frequently Asked Questions

Is it worthwhile to install hardwired smoke detectors?

Hardwired smoke alarms are recommended if you want dependable performance. They may apply a little more effort, but they will undoubtedly provide you with peace of mind. You won’t have to worry about it flying out of power because it will be connected to your home’s power source.

Kidde or First Alert: which is the better brand?

First Alert offers more functions than Kidde because of the alarm system with a vocal warning of the hazard.

How long do smoke detectors that are hardwired last?

If you want the most reliable smoke alarm cover, wired alarms can quickly provide ten years of protection; each notice must be updated every ten years.

Do hardwired smoke detectors have an expiration date?

Your smoke detectors are past their prime, according to the Fire Protection Association (nfpa, which recommends replacing them when they reach the age of ten years.

Similar Posts