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Our house was wired for smoke detectors -- specifically the rather cheesy BRK 4120SB, which delights in false "low power" chirping. My goal was to replace the ones in the bedrooms with combination alarms that would alert us not only to smoke but to the presence of carbon monoxide. (Not to scare you but harm and even death from carbon monoxide poisoning are definite risks, especially in a home with deep-sleeping teenagers.)

I needed units that would be compatible with the wiring of our current system, and ideally ones that would accept the power leads, as wired. After some research here and elsewhere, I called the BRK help line and got definite information about the unit that would be compatible, as well as locations within the home where I both should and should not install units.

I ordered two units to start with, still being a bit leery of my previous experience, and can say that installation took less than 5 minutes per device.

1. Follow the instructions for removing the plastic tab in the battery door of your new unit and pushing the button to test your new unit. If all's well, proceed. Disregard the "locking pin" stuff unless you are in a shared dwelling and are concerned with someone walking off with your 9-volt battery. (This was the weirdest part of the instructions, frankly, and this is my guess on why it's there.) **Important: you are listening for 3 tones, pause, 3 tones, pause, 4 tones, pause, 4 tones. There is a typo at the bottom of page 3 of the instructions, so I've just verified with BRK that the tone pattern I'm mentioning is the correct one.

2. Twist off and unplug your current unit.

3. Back the two screws holding your collar to the ceiling so you have enough clearance to remove the collar.

4. Install the new collar.

5. Install your new unit. (A wired plug is included in case you need to swap your existing plug for the new plug.)

Fellow owners of the 4120SB will find that the upgraded unit sets and locks into place in the ceiling *much* easier and more reliably. Ditto with the battery door. Note that on the SC9120B, if you're having problems with the battery door not shutting (a) there is a little trigger tab that you should be able to push down with a fingernail and/or (b) hold the unit upside-down.

***A word, please, about longevity, since the primary purpose of an alarm is your safety.

1. Replace your batteries at least once a year.

2. Combo smoke/carbon monoxide units have a 5-year life span, per BRK staff. Regular smoke alarms have a 10-year lifespan. Not replacing them within these timespans is, in my opinion, the most dangerous kind of false economizing. (Note also that if you need help, the BRK customer service apparently has improved greatly since the experience of earlier reviewers of the product line. The call I made in June could not have been more thorough and professional, even to dealing with the phantom beeps of my 5-year-old alarms.)

3. Whether or not you buy this or any smoke alarm product, please do yourself and your family two favors. First, label the plug (hidden) side of your units with the install and replace dates. Second, change your batteries at least once a year.

BTW, I gave the unit a 4 rather than a 5 because while the battery door and twist-on/twist-off issues are less irritating than on the earlier generation, they still do exist.
55 comments184 of 191 people found this helpful. Was this review helpful to you?YesNoReport abuse
on December 26, 2011
If I could give this zero stars, I would. The contractor installed them in my new home. The alarms would sound would every time I used the stove top, even for something like grilled cheese sandwiches. After a few months, they started sounding for no reason at all times of the day and night. After being woken up every night for a week, I disconnected all of the alarms, removed all the batteries because the alarms were still going off, and spent a large chunk of change to outfit my house with all new smoke detectors. Not exactly an expense I was anticipating in a brand-new home.
1313 comments108 of 115 people found this helpful. Was this review helpful to you?YesNoReport abuse
on May 7, 2012
I bought 3 of them from Amazon. The first one failed a month after the return period. The rest all failed within months. They would go off at all hours of the night. I would recommend against buying this particular model.
22 comments59 of 63 people found this helpful. Was this review helpful to you?YesNoReport abuse
on February 7, 2009
Received three BRK SC9120B replacements after original units (4 years old) started a low battery chirp with new Duracell batteries. Spoke with BRK rep. about problem and they sent three new units with Duracell batteries. The units worked fine for about two weeks before all three started to chirp a low battery signal. In that time our other three BRK smoke only detectors that were installed 4 years ago started the same chirping sound. Again called BRK and they were going to send us three replacements for them. After the nightmare of having six four year old BRK products fail in a matter of three weeks and three brand new replacement units fail in two weeks. I would stay away from BRK! I have read elsewhere about an issue with BRK and Duracell so I was a bit surprised when the new units arrived with Duracell batteries in them.
1919 comments108 of 122 people found this helpful. Was this review helpful to you?YesNoReport abuse
on December 21, 2010
I have a rental property and this year, the city's new regulation required installation of these detectors. One of the detectors malfunctioned and the terrified tenant called 911, who proceeded to do over 1000 dollars in property damage.

I subsequently found out that even the EPA has admitted that many of the CO detectors they tested were unreliable, and either went off at too low of a level or did not sound at dangerously high levels.

According to their website, the best way to keep the building's inhabitants safe is to have fuel-burning appliances properly installed and maintained by licensed professionals to make sure that the gases (including CO) are vented properly.

I ended up doing a lot of research related to CO as a result. I have the documentation from the Fire Department indicating the levels that they measured (WAY BELOW the low threshold on the detector) even near the detector.

I knew that a problem was unlikely since the heat wasn't even ON at the time.

Nevertheless, they broke into two apartments, destroying irreplaceable historic doors and frames. Even the fire chief told me that if I have a hard-wired smoke detector/CO detector combo, I should get it replaced as they have had false alarms with that type of detector. But as mentioned on the EPA website, and evidenced by many other reviews on Amazon etc, CO detection is apparently in it's infancy and I'm surprised that these detectors are even being sold, much less required by law.

Unfortunately, according to my lawyer, it's more trouble than it's worth to sue the city, so I had to suck up the CONSIDERABLE expenses myself. Not to mention my poor tenant, who was (unharmed of course) but anxious.

I am so ANGRY, but the only thing I can do apparently is to WARN other people about these alarms. If you have one in your house and there's a false alarm, that's one thing. But if a tenant has a false alarm, you are vulnerable in many different ways.

The WORST thing about this type of alarm is that if the CO part malfunctions, you've lost your smoke alarm as well. In addition, since it's installed high on the ceiling, if it false alarms, you have to get on a ladder to turn the thing off.

I would not recommend the first alert smoke/CO alarm to ANYONE.
1414 comments179 of 207 people found this helpful. Was this review helpful to you?YesNoReport abuse
on February 27, 2012
Terrible product. Malfunctioned after only 1 year. Woke my entire family up at five in the morning. Got,everyone out into the freezing cold, Bly for the fire dept. to tell me the unit is faulty. I see numerous complaints. Add me to the list.
11 comment26 of 27 people found this helpful. Was this review helpful to you?YesNoReport abuse
on February 7, 2010
These BRK smoke alarms have issued alarms twice now, which lasted several hours each and resulted in lost work time. Initially, two of these would beep every minute and nothing I tried would stop it, so I had them replaced, and then these seemed to be OK, but almost every night we would hear a 1 second alarm. Then 2 weeks later, the alarms went off steady and nothing we tried would silence or reset them. We even had the gas company come out to check the gas applicances for CO2, since 2 of the units also had the CO2 detectors built in, but everything checked out fine, so I just started unplugging the units until the alarms stopped. A few days later, the remaining 3 alarms that I still had connected started another false alarm and eventually stopped. I don't have time to put up with issues like this, and it can result in not even believing your smoke alarms, when it may be a real fire! I only purchased these because they were plug compatible with the First Alert, but I will have to rewire the plug and purchase a better quality brand.
0Comment25 of 27 people found this helpful. Was this review helpful to you?YesNoReport abuse
on October 24, 2011
My condo unit had this alarm installed when I moved it. It was located at least 25 feet from the kitchen, around a corner and down a hallway, where there is plenty of air circulation. But it was so overly sensitive that it would go off nearly every time I used the cooktop. Never mind that nothing was smoking. It would even go off when I used the oven to bake a cake, for god's sake! When it went off while I was gently sauteeing mushrooms, on the back burner with the vent fan already on, I had had enough. In an apartment with no proximity to a furnace or a kerosene heater, I am not concerned about CO. And if every time I cook I have to open every window in the place and put the vent fan on full blast, I'll do without. An alarm that goes off all the time is as bad, or worse, than no alarm at all. I pulled it out and removed the battery.
22 comments24 of 27 people found this helpful. Was this review helpful to you?YesNoReport abuse
on January 19, 2012
To make a long story short, my tract home built in 2008 was equipped with all First Alert Smoke and CO sensors throughout. Last night, mine failed after less than 4 years of use sending out an alarm that carbon monoxide was detected in the home. The fire department responded and reported no excessunive CO readings in the home.

I called First Alert for a warranty replacement. However, being that I am not the original homeownner, they would not grant a replacement.

Sorry folks, this is BS...this is not just some unnessesary product...this is safety, required in each and every new build in this state. And as a safety piece of equipment, the warranty should be carried out regardless of who owns the house...original or resale.

I urge everyone to write the local fire department and their state representatives to have safety companies stand behind their product!!
11 comment27 of 31 people found this helpful. Was this review helpful to you?YesNoReport abuse
on December 25, 2013
Perfect replacement for the 2 BRK units I had that were at end of life.. The new ones were 1st alert brand/BRK and hooked up perfect without changing the cover plate. Plugt in and twist in the unit and I was done.
The only thing that you need to be aware of is in the normal life cycle you need to vacume the unit once a year or on backup battery change. I have no issues with false alams.
0Comment16 of 17 people found this helpful. Was this review helpful to you?YesNoReport abuse

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