Customer Reviews For The Hardwired Carbon Monoxide Alarm with Battery Backup

Overall Rating

4.8
84 Reviews
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81 customers recommend this product

Product Reviews

John D
October 4, 2025
Verified Purchase
LIFE SAFETY

EXCELLENT SERVICE AND PRICING

Laura G
July 11, 2022
Verified Purchase
Customer Review

Very fast shipping! Arrived safely.

William H
May 18, 2022
Verified Purchase
Customer Review

Quick shipping

Christopher S
March 31, 2022
Verified Purchase
CO Alarm

The process of purchasing the new CO Alarm was fine. I did though like the old model CO5120PDBN, with the digital display better than looking up what the beep sequence is indicating.

John K
March 7, 2022
Verified Purchase
First alert carbon monoxide

Works good

Ivano B
February 18, 2022
Verified Purchase
Direct replacement

Quick ship plugged in to existing wiring .

Richard Wambolt
December 18, 2020
Verified Purchase
First Alert CO5120BN Carbon Monoxide Alarm

My old detector quit working and this one fit perfectly. Easy install.

Tom Avezzie
December 17, 2020
Verified Purchase
Customer Review

Very good

Tom Avezzie
December 17, 2020
Verified Purchase
Customer Review

Very good

Richard Bear
October 22, 2020
Verified Purchase
Mounting Issues

Alarm does not stay affixed to base - purchased 2 units and had to use double side adhesive tape to secure the units to their base.

Barbara Cilla
October 12, 2020
Verified Purchase
Customer Review

Great customer service

Cecile Aylett
September 8, 2020
Verified Purchase
Customer Review

Very satisfied with items and service - courteous and helpful over the phone.

Leslie Garrick
August 6, 2020
Verified Purchase
CO update

Installed to existing frame - a snap

Kathleen Brown
June 29, 2020
Verified Purchase
Customer Review

Excellent service, fast delivery.

Patrice Lawlor
June 17, 2020
Verified Purchase
Carbon Monoxide Alarm

I received my First Alert Hardwired Carbon Monoxide Alarm with Battery Back-up in the time frame I was supposed to. It was very easy to install.

Kelly Thimm
June 9, 2020
Verified Purchase
Customer Review

My old detector quit working and this one fit perfectly. Easy install.

Kenneth Lawrence
December 9, 2019
Verified Purchase
Customer Review

Works great.

Kenneth Numerowski
November 12, 2019
Verified Purchase
co detector purchase

Product was delivered in a timely manner at a competitive price.

Ronda Kleeberg
September 23, 2019
Verified Purchase
Customer Review

Easy to install and had the same wiring which made it very simple to switch out the old ones!

Stephen Fritch
July 11, 2019
Verified Purchase
Purchase review

Ordered carbon dioxide detector from First alert store. They processed and sent the detector without delay. Called with mailing concern and they quickly and efficiently helped. A great Co. to work with and product is exactly what I needed. The web site is great. Thank You First Alert!

Product FAQs

How do I get my carbon monoxide alarm to stop chirping?

If your carbon monoxide alarm keeps chirping, the battery may be low or weak. On First Alert carbon monoxide detectors, check to see if the battery light is yellow or green. If the alarm is chirping and the light is yellow, it means the battery is low. The way to get a carbon monoxide alarm to stop chirping is to replace the battery.

Where should I install carbon monoxide alarms? What is proper carbon monoxide alarm placement?

It is very important to install carbon monoxide alarms near or in each separate sleeping area. Many states now require that a carbon monoxide alarm is placed in each bedroom. For added protection, placement of an additional carbon monoxide alarm at least 15-20 feet away from the furnace or fuel burning heat sources is recommended. Also, install carbon monoxide alarms at least 10 feet from sources of humidity like bathrooms and showers. In two story houses, install one carbon monoxide alarm on each level of the home. If you have a basement, carbon monoxide alarm placement is recommended at the top of the basement stairs.

Is there anywhere I shouldn't install carbon monoxide alarms?

Do not install carbon monoxide alarms in garages, kitchens, furnace rooms, or in any extremely dusty, dirty, humid, or greasy areas. Do not install alarms in direct sunlight, or areas subjected to temperature extremes. These include unconditioned crawl spaces, unfinished attics, un-insulated or poorly insulated ceilings, and porches. Carbon monoxide alarms should not be installed in outlets covered by curtains or other obstructions. Do not install in turbulent air-near ceiling fans, heat vents, air conditioners, fresh air returns, or open windows. Blowing air may prevent carbon monoxide from reaching the CO sensors.

How many carbon monoxide alarms should I have in my home?

So how many carbon monoxide alarms should you have in your home? The National Fire Protection Association (NFPA) recommends that you should have a carbon monoxide alarm centrally located outside of each separate sleeping area in the immediate vicinity of the bedroom. For added protection, you should have additional carbon monoxide alarms in each separate bedroom and on every level of your house, including the basement. Some states now require that you have a carbon monoxide alarm in each bedroom of the house. If you install only one carbon monoxide alarm in your home, place it near or in your bedroom.

What is the proper way to do a carbon monoxide alarm test?

The following procedure is the proper way to do a carbon monoxide alarm test - Press and hold the Test Button on the front of the alarm until the alarm sounds. Be sure you hold the button down long enough; it can take up to 20 seconds for the alarm to respond to the test.

Is it a false alarm when my carbon monoxide alarm sounds and there doesn't seem to be a problem?

A carbon monoxide alarm false alarm should not occur if your alarm is in working order. Remember, carbon monoxide is an odorless, colorless gas. If your carbon monoxide alarm went off, it detected potentially harmful amounts of carbon monoxide. After the professionals have evaluated the situation, make sure no one has any symptoms of carbon monoxide poisoning.

Here are a few situations that may cause a carbon monoxide alarm "false alarm:"

  • The carbon monoxide alarm needs to be relocated. Carbon monoxide alarms should be located 15-20 feet away from all fossil fuel burning sources like furnaces and stoves. Alarms should be located 10 feet away from sources of humidity like showers.
  • Fossil fuel burning appliances may not be burning fuel completely. Check pilot lights/flames for blue color. Appearance of yellow or orange flames indicates incomplete combustion-a source of carbon monoxide.

Will carbon monoxide alarms detect explosive gas leaks?

No, a single function carbon monoxide alarm reacts to carbon monoxide only. To detect explosive gas, you need an explosive gas detector. Different kinds of explosive gas can be detected and it is recommended that any home that utilizes natural or propane gas have at least one explosive gas leak detector.

CO5120BN Video Guide

Watch this helpful video to learn more about the First Alert Hardwired Carbon Monoxide Alarm with Battery Backup - CO5120BN.

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