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
Click Here to Write a Review for this Product. Review

Average Rating Based on 210 reviews: Rating: 4.94761904761905/5Rating: 4.94761904761905/5Rating: 4.94761904761905/5Rating: 4.94761904761905/5Rating: 4.94761904761905/5 (4.9)

Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5 Replacement alarms - 03/19/2019
Reviewer: Richard Molnar
I purchased replacement alarms identical to the ones that came with my house and were 10 years old. They were easy to install and work as flawlessly as my other alarms.


Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5 Perfect replacement - 03/18/2019
Reviewer: Robert Sutphin
Needed to replace a fire alarm that had begun to malfunction. The new one arrived quickly, packaged well and I was able to plug it in without replacing the base.


Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5 - 03/18/2019
Reviewer: Judith Baker
Easy to install. Didn't need an electrician for hardwire if replacing with like kind.


Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5 Tom - 03/18/2019
Reviewer: Taher Mohammed
Product worked as expected and was also able to communicate with other alarms in the home.


Rating: 4/5Rating: 4/5Rating: 4/5Rating: 4/5Rating: 4/5 Great price! - 03/15/2019
Reviewer: William E
The price was great. Cheaper than anywhere else. Fast delivery. No fire or smoke, so I can't comment on how well it works.


Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5 9120B - 03/14/2019
Reviewer: Floyd Schmitz
Ordering was very simple and the service was fast. Was able to replace my older First Alert smoke alarms eight in all in about 90 minutes. This included replacing the ceiling brackets. Yes, the new smoke alarms were compatible to the old brackets, but for a cleaner look it was easy to replace the old brackets with the new ones. I was very pleased that the smoke alarms came with the 9-volt batteries.


Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5 It connects with all the other ones we have - 03/14/2019
Reviewer: Shawn Long
This was easy to install and connects with all the others we have.


Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5 Quick and easy swap out - 03/12/2019
Reviewer: Gerald Lomashewich
Replaced an earlier version of this smoke detector. The new detectors used the same hardwire connection as the old one. Just had to replace the base on the junction box and put on the new smoke head. Easy! and my house is up to date for another 10 years. Great service and shipping from the First Alert online store. If you need First Alert products, just go to the online store. They will have what you want.


Rating: 3/5Rating: 3/5Rating: 3/5Rating: 3/5Rating: 3/5 No Problems - 03/11/2019
Reviewer: Brian Hernandez
No issues. I tried calling on the weekend, but Sales Desk apparently is only open on weekdays. I called the service number and, since the smoke detector that I was replacing was over ten years old, the service desk helped me to ID the proper replacement model. I then went and ordered it online. Product arrived less than a week later. All good.


Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5Rating: 5/5 Perfect Match - 03/11/2019
Reviewer: Mark Messina
The smoke detectors that I needed to replace were old, this unit was the exact fit and the plug for the wiring was the exact match. Very easy to install!


Read All Reviews
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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