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).
  • Emits T3 Pattern.
  • 10 Year Limited Warranty.
  • 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

5

Average score based on 355 reviews

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

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

Reviewed: 04/07/2020 by Joseph Coulter

Could not of been easier

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Fast service at a reasonable price!

Reviewed: 04/06/2020 by George Lazur

The products are of high quality and are priced very reasonable , plus free shipping.

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

Reviewed: 04/05/2020 by Christy Krainess

I replaced an older model and I love the new ones they were easy to install and work great

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

Reviewed: 03/25/2020 by GB fan

Wasn't able to find one in any stores to replace an old one I had. Thankful to be able to order online with fast shipping...had it in 3 days. Plugged into already wired and attached to existing connection. Easy

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Amazons Price Gouging

Reviewed: 03/24/2020 by S Thomas Church Jr

I needed to replace an old First Alert hardwired Smoke Alarm that was still working after 30 years in my finished basement. It was discolored so I called First Alert and was given the exact replacement. Once I had the model number I tried to find it on Amazon but they showed multiple versions so I called First Alert again and the tech asked me how much did it cost and he was amazed that it cost 4 times what First Alert Store offered on line. I immediately ordered the replacement with free shipping and saved over $30 versus Amazons price. I recommend that anyone that is planning on purchasing First Alert Smoke alarms that they call the First Alert on-line store always. Plus I had on-line excellent technical help on how to uninstall and install the smoke alarm. This is not the first time that I realized that Amazon practices price gouging, in fact, I am awaiting an investigation from Amazon as to why a physicians practice offers an identical item for 10% higher price. Buyer Beware!!

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/55 Alarms

Reviewed: 03/23/2020 by chuck lovsey

We had these alarms in our home and they where malfunctioning so I just replaced them all, works fine now.

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Real value!

Reviewed: 03/22/2020 by George Lazur

The 9120B smoke detector replacing my 17 year old unit is a very good product and great value!

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Excellent Replacement

Reviewed: 03/20/2020 by Terrance Tobias

We ordered 3 9120B Hardwired Smoke Alarm with Battery Backup detectors to replace our 12 year old models. The new detectors fit the old mounts and electrical connections perfectly. The First Alert staff were helpful in answering my questions prior to placing the order through the First Alert Store online. Great customer service to a loyal customer.

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Smoke Alarm

Reviewed: 03/18/2020 by Darrell Abel

Replaced old 4120B alarms. Simple plug in and done.

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

Reviewed: 03/17/2020 by Luther Weatherby

Order was received earlier than I expected it and units excellent quality.

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Exact replacement

Reviewed: 03/12/2020 by Daniel L Whan

Installed no problem

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Easy to Install Replacement

Reviewed: 03/09/2020 by Gary C Woodward

SInce I was replacing identical units I did not need to mount a new mounting plate or do any new wiring. I just twisted the old one off the mounting plate and disconnected a connector and then reconnected the new unit and twisted it into the existing mounting plate. It could be as quick as 5 minutes a unit including some time to confirm power leds are on and test it. It even comes with batteries.

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

Reviewed: 03/06/2020 by Jonny Terra

Exelent and fast service

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5In my opinion

Reviewed: 03/04/2020 by Dave Adams

The people working here were kind and helpful. My 10 ,16 yr old detectors needed replaced and I got them fast and at a good price. Easy to change out and working well. Thank you all..

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

Reviewed: 03/02/2020 by David Campbell

I purchased these as replacements that were installed in my new construction home. I believe the original detectors were not protected from dust causing them to malfunction. These alarms are sensitive loud and interconnected so you can't miss an alarm. Ordering directly from first alert is the best way to go. Saved 30% compared to retail and delivered for free to my door. Very pleased.

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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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