First Alert Hardwired Smoke Alarm with Battery Backup - 9120B

  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
  • First Alert Hardwired Smoke Alarm with Battery Backup - 9120B
Ionization Wired In Smoke Detector
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Hardwired Smoke Alarm with Battery Backup:

Designed to help promote household safety, the First Alert 9120B Hardwired Smoke Alarm with Battery Backup can provide a vital early warning of fire. This hardwired smoke detector uses an ionization smoke sensor to reliably detect smoke from hot, fast-flaming fires.

Ionization Sensor Reliably Detects Flaming Fires

The First Alert 9120B Hardwired Smoke Alarm with Battery Backup comes equipped with an ultra-reliable ionization sensor to provide the earliest possible warning of a fast-flaming fire. The sensor is optimized to detect flaming fires, such as those caused by paper, kitchen grease, and other fast-combusting materials.

Gasket-less for Easy Installation

To facilitate hassle-free installation, this smoke alarm features a streamlined mounting system with a gasket-less base. The mounting bracket keeps the alarm secure over a wide rotation range while maintaining perfect alignment. The alarm also comes with a dust cover to keep the unit clean during construction. AC-powered smoke alarms must be installed in accordance with all local electrical codes.

Battery Backup for Detection During a Power Outage

This smoke alarm is designed for hardwired installation, but it also features a battery backup that helps ensure continued functionality in the event of a power outage. The unit comes with a 9-volt battery and features a pivoting, easy-to-access battery drawer that allows you to replace the battery without dismounting the alarm.

Works in Tandem with Other First Alert Alarms

In addition to functioning independently, this smoke alarm can also integrate with up to 12 other First Alert or BRK hardwired alarms for coverage of larger spaces. It also integrates with up to six other compatible devices, such as bells, horns, and repeaters. If one alarm in the series is triggered, they will all sound. The alarm features a latching indicator to identify which unit triggered the alarm, alerting you to the area of danger.

First Alert Smoke Alarm 9120B

Recommended replacement for the following obsolete models:

BRK 4120B
BRK 4120SB
BRK 86RAC
First Alert SA4120B
First Alert SA4121B
First Alert SA4919B

Hardwired Smoke Alarm with Battery Backup Features:

  • Ionization smoke sensor is optimal for detecting fast flaming fires.
  • Loud 85dB alarm.
  • Tamper resistant locking pins.
  • Single button silence/test.
  • 120V AC power with 9V battery backup (included) to keep alarm functioning during power outage.
  • Open mounting design for easy installation with side load battery compartment for quick replacement.
  • Interconnectable up to 18 units (12 smoke, 6 CO/heat/relay).
  • 10 Year Limited Warranty.
  • Emits T3 Pattern.
  • Product Dimensions (LxWxH): 5.6 x 1.9 x 5.6 in.
  • Product Weight: .60 lbs.
Product Specs
UPC:
029054015327
MPN:
9120B
Write A Customer Review Review

4.9

Average score based on 230 reviews

Rating: 4.94347826086956/5Rating: 4.94347826086956/5Rating: 4.94347826086956/5Rating: 4.94347826086956/5Rating: 4.94347826086956/5

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Smoke alarm

Reviewed: 05/20/2019 by Lyle Parkins

Best alarm you can buy not only smoke but carbon dioxide also

Rating: 3/5Rating: 3/5Rating: 3/5Rating: 3/5Rating: 3/5Matching alarms

Reviewed: 05/18/2019 by Michael Hastriter

Good product came with dust shield to limit construction particles. Mounting plastic rings did not come with screws which was inconvenient. Devices took awhile to arrive but the price was very reasonable. Most importantly, these alarms matched the ones already in our home.

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5First Alert Hardwired Smoke Alarm with Battery Backup - 9120B

Reviewed: 05/16/2019 by George Watson

Ordering was easy, shipping was prompt, installation was a simple swap out, and we are now set for another 10 years. Thanks First Alert!

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5replaced 10 old alarms

Reviewed: 05/07/2019 by Joan Steinberg

First Alert customer service was great. Easy ordering and fast shipping. Best price on the internet. The real deal

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5

Reviewed: 05/06/2019 by Ralph Verni

Exactly what I ordered. Very happy

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Reliable company

Reviewed: 05/02/2019 by Dawn Cinker

This compnay always ships immediately and gives updates. I highly recommend

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5First Alert Model 9120B Smoke Alarm

Reviewed: 04/30/2019 by SGM Pete

My choice for 19 years. Reliable and affordable.

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Reviewing my purchase

Reviewed: 04/30/2019 by Randall Arndorfer

Great product and very good price. A life saver!

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Randy

Reviewed: 04/29/2019 by Randall Rogers

Very pleased with first alert. Very easy to install and good price. Highly recommended

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Randy

Reviewed: 04/29/2019 by Randall Rogers

Very pleased. Simple operation and easy to install. Highly recommended.

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Perfect replacement

Reviewed: 04/18/2019 by Glen McPheeters

As my home is now 10 years old, some of the installed as new First Alert smoke detectors are beginning to fail. The low battery chirp doesn't stop even with a new battery. As such, I purchased a supply to replace them as needed. The replacements are a perfect plug & play replacement. Just unplug the old, plug in the new, and fit it on the existing ceiling plate. 1 minute job. Couldn't be happier, and, the price was right, with free shipping as well!

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5smoke alarm 9120B

Reviewed: 04/17/2019 by Mark Potter

Arrived as promised. Each unit was perfect with Battery included. Easy installation. Great Experience with the entire order process.

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Pete1955

Reviewed: 04/06/2019 by Raul Pedrozo

Easy to install and worked perfectly

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5works great

Reviewed: 04/03/2019 by Shawn Long

This smoke alarm works great and with all others in the house.

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Just as ordered

Reviewed: 04/01/2019 by Phil Sellars

Got this unit to replace a 10 year old First Alert installed in my home which wouldn't stop chirping. New unit was hard to install using the existing pigtail connector but finally managed to get seated. Other than that installation was simple.

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Q: What is the proper placement of smoke alarms?
A: It is important that you have the proper placement for your smoke alarms. Install your alarms at least 20 feet from appliances like furnaces and ovens, which produce combustion particles. Alarms should be at least 10 feet from high humidity areas like showers and laundry rooms, and at least 3 feet from heat/AC vents. Be sure to install a smoke alarm in each bedroom, one at the top of each stairwell, and one on every level.

Q: Why doesn't my smoke alarm sound when I push the test button?
A: It is important that you frequently test your smoke alarms. When you are testing your smoke alarm, there are a number of reasons why the alarm might not sound:
  • You may not be holding the test button down long enough. Try holding it down for up to 10 seconds (20 seconds on photoelectric models) .
  • Your battery may not be installed properly or snapped all the way in place. Even if the alarm sounded briefly when the battery touched the terminals, you still need to make sure it is snapped securely in place. If the battery is loose, in cannot power the smoke alarm properly. After installing new batteries, be sure to test your smoke detector.
  • Your AC power may not be on. AC and AC/DC units will have a power indicator light (red or green) that shines continuously when they are receiving electrical power.
  • If you have a 10-Year model, the smoke alarm may not have been properly activated. If the tab broke away before the alarm was activated, you can use a toothpick to move the switch over to test the alarm.

Q: Why does my smoke alarm go off when I install a battery or turn on the AC power?
A: It is normal for smoke alarms to go off and sound briefly (up to 5-10 seconds) when you install a new battery or when they are powered up. If the alarm continues to go off and no smoke is present, the cause may be one of the following:
  • There may be insufficient battery power, try new batteries.
  • Problems with voltage or insufficient electrical power (brown out) may cause a continuous weak sounding alarm. For AC or AC/DC models, temporarily disconnect power at the service panel until the brown out is over. If you do not restore the AC power, your smoke alarms cannot warn you of a fire.
  • Incompatible warning device. If an incompatible alarm or auxiliary device is linked into a series of AC or AC/DC smoke alarms it may cause the system inadvertently go off.

Q: I lost my First Alert smoke alarm owner's manual. How can I get a new one?
A: First Alert smoke alarm owner's manuals are available online for download at no cost. Find your alarm in our Smoke Alarms section.

Q: Why does the National Fire Protection Association (NFPA) recommend that home smoke alarms be replaced after 10 years?
A: Smoke alarms have a limited life. Although each smoke alarm and all of its parts have passed many stringent tests and are designed to be as reliable as possible, any of these parts could fail over time. Therefore, you must test the devices weekly. The unit should be replaced immediately if it is not operating properly. The performance of smoke alarms older than 10 years is simply not reliable. To ensure your family's safety, all carbon monoxide and smoke/CO combination alarms need to be replaced every 5-7 years. All smoke alarms need to be replaced every 10 years.


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