I purchased two of these after being unhappy with First Alert ZCOMBO made for Ring, which I returned. This model interconnects with other SCO500B models so that if there is an alert in another part of the house, all alarms beep and give a voice alert. These units cannot connect to my Ring Alarm system. That is fine with me as I discuss in my review of the ZCOMBO model. I had no problems at all with setting up these two units and choosing the voice location feature. So far, no false alarms and the units are working fine. I have read the "one star" reviews and people have had false alarms after a period of time. Mine have been up for one week with no problems but if I start getting false alarms, I will update this review. The distance that these interconnect seems good as I have tested these two in different parts of my house. I will probably buy two more for other areas. One thing that I like about this design is that if it detects CO, the alarm goes off and then it speaks the CO level to let you know how much CO has been detected. As I discussed in my other review of the ZCOMBO unit, people should not just assume that getting a CO alarm means that the unit is broken. There are many possible reasons why CO may be in your house and before declaring them defective, it is important to get a professional or the fire department to check your house. If you do an online search of CO in your house you will see that it is possible that a crack can develop in a furnace causing CO to mix with the heated air. Also, gas appliances such as heaters and even gas stoves, if not vented correctly can cause CO to enter a house. If one of these signals a CO alarm, take it very seriously because your life could be at risk. Don't ever assume that the alarm is simply broken until you are absolutely sure it is. I read a review of this item saying that the alarm on these units might not be heard by older people with hearing loss. The alarm on these units is very loud and someone would really have to be very hard of hearing to not hear this. In fact, when setting these up, you should probably wear ear protection because the alarm is very loud. I would recommend that people wear ear plugs even when testing these alarms. When setting these up, it is important to follow the instructions on the enclosed sheet because it is not easy to figure out without instructions. I found that the setup was easy when following the instructions. There are also some reviews here that have setup instructions, which can also be helpful. I consider these the best units that I could find for warning me about fire or CO when I am home. The only problem is that it will not notify me if I am away from home. I have decided that I am also going to buy two Nest Protect Smoke/CO alarms, one for each level of my home and in rooms that do not have this unit, the First Alert SCO500B. It is simply too expensive for me to buy six Nest Protect alarms which would be close to $700. I think that buying four of these units and two Nest Protect units, I can get a good smoke/CO alarm system at a reasonable price. In the future, if I decide that I want to connect these alarms with my Ring Alarm system, I will purchase a Ring Listener which is designed to be installed near and alarm and will send an alert to the Ring alarm monitoring company. I am still worried about connecting my Ring Alarm with smoke/CO detectors. The reason is that if there is any type of alarm sent, even false ones, Ring monitoring will send out the local fire department and they cannot be recalled. In my city, false alarms will get fined at increasing amounts and your alarm license can be banned for too many false alarms. I think that the First Alert SCO500B is a good smoke/CO alarm and I would recommend this model. Realize though that all smoke alarms are now designed to have a seven year life span. So know that in seven years all these units will have to be replaced with new ones.

Just installed this week as required by the building inspector. Interconnection worked fine and satisfied the local code, it is super loud and uses an english speaking voice to alert you where the fire or CO problem is detected in your home.

I've been using these smoke/carbon monoxide detectors for a while now and hoped I'd never need them. Then the unthinkable happened: one day after having some work done on a gas appliance in my house, a carbon monoxide leak started. I called in the fire department, and they brought in their own calibrated meter. After clearing the carbon monoxide and talking to us before leaving the scene, they were impressed with these detectors and had to know what they were. It turns out the voice-activated reading from these detectors was only 1ppm over the reading of their calibrated handheld. For something as mass-produced and inexpensive as these are, that's HIGHLY impressive! Also, everything they tell you about a carbon monoxide leak is true. Had these detectors not went off, there would have been no way we could've known there was an issue. I ended up buying these on a whim, and they saved my family from being affected by carbon monoxide that, according to the fire department, was well over 10 times the lethal limit. If there's a combination CO/smoke detector that gets my endorsement, it's this one. It works perfectly. Buy it and don't think twice.

Smoke and Carbon Monoxide detectors/alarms are extremely important for every home. People hate to spend the money on them, especially the higher quality (more expensive) detectors, and yet your very life can depend on them. There are many choices on the market today, ranging from cheap, basic models to extremely expensive, high-tech devices. There are two main types of smoke detectors: ionization detectors and photoelectric detectors. Most detectors utilize either one or the other of these technologies while some use both. Most detectors just use a beep-style audible alarm, while some talk, some have strobe lights, and some have a bright light to illuminate a dark area. Many detectors today are combining a smoke and carbon monoxide sensor, so you have dual protection in a single device. You can choose between AC and battery operated devices. Most (if not all) new homes are built with AC detectors in all of the vital areas, which usually contain a battery backup in case of a power outage. Many of these new detectors, installed in new homes, are linked together so that one detector will trigger all of them to sound their alarm. This is a very useful feature, since an alarm in the basement may not be heard by sleeping individuals in an upstairs bedroom. However, getting this protection in an existing, older home was almost impossible until a few years ago when manufacturers started utilizing wireless technology to allow communication between multiple detection devices. My wife and I recently decided to move our bedroom into the basement level of our home. It allowed our three children to all have a room of their own, but we were very concerned about what would happen if there was a fire and we did not hear an alarm go off on the upper level of our home. We were also concerned about the potential of carbon monoxide poisoning. It is the first time that we were not sleeping close to our children, as we were now down a level and on the complete opposite end of our home. We had a home security system installed, which also gave us some protection from fire, but we could not afford to have an adequate number of smoke and carbon monoxide sensors installed with it, as they were extremely expensive. Our security system is made by First Alert Pro, and when I explained my concerns about better protection, to the person installing the system, he recommended that we look into the OneLink combination smoke and CO alarms by First Alert. He told us that when one alarm goes off it sends a signal to every other OneLink detector in the house, causing all of the alarms to go off at the same time. He also told us that the alarms have a talking voice module, which actually tells you where the smoke or carbon monoxide is being detected. Research also shows that young children are more likely to wake up and take action when they hear a voice, rather than just hearing a beeping sound. I don't know much about that but I have read this information in several places on the Internet. I could not find the OneLink combination smoke and CO alarms at any local retailers, but I was able to find them at several sites on the Internet. Needless to say, they are not cheap! However, after researching this model online, I was impressed by the features and I read a lot of glowing reviews for them. Since you can add as many detectors as you want, whenever you want, I decided to start out with three of them and add more as I could afford them. The included instruction manual is pretty straightforward but setting up and installing the first detector was a little tricky. It's not that complicated but timing is a key element in programming this alarm. You start out by installing 2 AA batteries (included in the package), which will cause the alarm to say "Welcome, First Alert Smoke and Carbon Monoxide Alarm. No location programmed. To select location, press and hold test button now." This is where the timing part comes in. As instructed, you press and hold the test button until the Alarm starts speaking again, at which time you release the button again. When you do this, the voice module will say "To save location, press and hold test button after desired location is heard." The voice will then begin listing off room names in a typical house. The choices are as follows: Basement, Living Room, Family Room, Office, Kitchen, Dining Room, Hallway, Child's Bedroom, Master Bedroom, Guest Bedroom, Utility Room. Once you hear the name of the room that you want to setup the detector for, you must quickly press and hold the button down. It will announce the room name you have chosen and will tell you that the location has been saved. If you mess up this step, you can remove the batteries, wait for a couple of minutes and reinstall the batteries again, to start the entire process over. To add and link additional OneLink alarms, you must hold down the test button when you insert the batteries. Once you hear the unit chirp you release the button. At this point the green power LED should start to blink. You are then to hold down the test button on the first alarm you setup, until the second alarm chirps. You repeat these steps for each additional OneLink alarm you wish to integrate into your home. Once you have the main programming completed, mounting the devices is as easy as installing any other basic smoke detector, using the provided mounting screws. My wife and I started by purchasing and installing three of the First Alert OneLink Battery Operated Combination Smoke and Carbon Monoxide Alarms (SCO501NC-3ST). As all First Alert OneLink devices can be linked with each other, we will likely add a few smoke-only detectors in the near future. We have installed one of the OneLink detectors in the kitchen, one in the hallway (right outside our children's bedrooms), and one just outside our bedroom in the basement. So far they have been working flawlessly. We test them every couple of weeks or so, and pushing the test button on one detector causes them all to go off, as they are supposed to. The real test was when my wife recently had a "cooking accident," which caused a fair amount of smoke in the kitchen. The alarm in the kitchen went off first, which triggered the other two OneLink alarms in the house. I was in my office downstairs when the basement alarm sounded; saying "Warning, Evacuate, Smoke in Kitchen, Evacuate!" Shortly after I silenced the kitchen alarm, the hallway alarm went off, which set off the other two alarms as well. This time the spoken warning stated that smoke was detected in hallway. The alarms simply added to my wife's frustration in trying to get the burning dinner situation under control, but I was delighted that the alarms were working as promised. The First Alert OneLink Combination Smoke Alarm and Carbon Monoxide Detector allows you to build a safety network of wireless, interconnected alarms in your home. You can wirelessly connect up to 16 OneLink alarms in your home. When one alarm sounds they will all begin to sound. This device features a talking alarm, with an actual voice that speaks the type and location of the danger in your home. It is a 2-in-1 device, giving your home protection from both smoke and carbon monoxide. The smoke detector uses photo-electric technology, which helps prevent false alarms like those caused by cooking and shower steam. An EZ access battery drawer provides the ability to change the batteries without removing the alarm from the ceiling. The CO sensor is an electrochemical type, which is the most accurate technology available for detecting carbon monoxide. The OneLink produces a loud, 85db alarm, plus a talking alarm for added safety. The package includes the OneLink combination smoke and CO detector/alarm, a pair of AA batteries, mounting hardware and instruction manual. First Alert claims that this device has a 6-year lifecycle. The OneLink alarm will give a special chirping pattern, to let you know once the device has reached end of life. The device is covered by a 5-year limited warranty. My wife and I are extremely happy with our purchase of the First Alert OneLink Combination Smoke and CO detectors. We no longer have to worry about an alarm going off upstairs, while we are asleep downstairs and therefore unaware of the danger to our children. We sleep much better at night knowing that our entire family is safe. I definitely plan to install more OneLink detectors throughout our home in the near future. Although the setup can be a little tricky, your first time, it gets easier as you program more of them. My only concern is the battery life, since they run on just two AA batteries. The instruction manual suggests that you test the alarms once every week, but to save battery power I test ours once every other week. The alarms do have a talking low battery alert, which is supposed to sound every 5 hours or so when the batteries are in need of replacement. We have had our OneLink detectors installed for about 3 months now and have had no problems with them. I cannot give the OneLink detectors 5 stars, due to their inflated cost, but I think they deserve 4 and ½ stars for their quality and advanced technology. I definitely would not want to be without them in my home and I highly recommend them to everyone.

I bought several of these smoke detectors over a year ago. They were a bit fussy, noisy, and time-consuming to set up, but no complaints once everything was up and running. One recently stopped working, however, so I called First Alert warranty department - within 5 minutes, a new one was on its way to me. They've turned me into a lifetime customer!

Our last house had hard-wired alarms which we had installed as part of a big remodel we did 20 yrs ago, 1 in each of 4 bedrooms, the hallway, the family room, the living room, and 2 in a very large home office/studio/work area. When we moved into our current place it had only 3 battery-powered alarms, 1 on each level, and I wanted the same reliability of connected alarms, but the cost of re-wiring was more than we could afford. I did some research and was hesitant about wirelessly-connected alarms at first, because the reviews didn't strike me as enthusiastic or that the alarms were reliable to the point of staking one's life on them. As time wore on my anxiety about having just the minimum number of alarms just nagged at me. I took a little gamble and ordered some of these. They were easy to install and easy to program. The also have a feature that lets you choose from a list of locations (that are common to most homes) to be spoken as part of the alarm, so you know the location/room of which alarm triggered the announcement. That's something even our hard-wired units didn't do. They use 2 AA batteries each, which are easy to replace simply be twisting/'unscrewing' the alarm unit from its' mounting plate. No screws must be unscrewed to replace the batteries, but they DO have a locking feature that is a plastic "pin" that comes as part of the unit and can make it difficult to open the battery compartment. You do NOT need to use it for the alarm to function, but it seems like something useful to landlords if renting out space. I did not use the pin to lock the battery compartment, as we're empty nesters and my spouse won't use a step stool yet alone a ladder. All mine are mounted on ceilings, so I need a step-stool/ladder to reach them, but they remove very easily. It's VERY unlikely anyone in our household is going to fiddle with the batteries. Know that the programming is a 2-step process when you are connecting more than 1 to the alarm "loop". The instructions were pretty easy to follow, and after connecting 2 or 3 units, you'll likely be able to do it without referencing them. NOTE THAT THE PROGRAMMING INSTRUCTIONS ARE ON A SEPARATE PAPER FROM THE INSTALLATION INSTRUCTIONS. The documentation states that each alarm unit should be within 100 feet of the next nearest unit, likely more than adequate for most homes. I installed 4 in August of '23, and now, more than 8 months later, have had no false alarms yet. I like them so much I ordered more for additional locations throughout the house. (I'm a heavy sleeper and also am hearing impaired and wanted to increase the likelihood of hearing any alarm). Note, too that YOU DO NOT NEED TO PROGRAM THEM FOR CONNECTIVITY, but if you don't, you might do better buying single units without the communication feature. Pricier than "single" units, yes, but if you want the extra protection of connected units and you need/want combination Smoke/CO2 alarms and can't/don't want to spend the money for hard-wired units, , I'd recommend these.

We bought these to install in the home we bought recently. There were none in this home previously. The mounting hardware, the actual anchors are inferior. You will have to purchase anchors to mount these. The ones included are so flimsy that they buckle under the stress of insertion into the hole you drill for them. Other than that, this is a superior item. Having smoke/fire and CO2 monitors in every living area in the house brings me great peace-of-mind, and this exact model received among the highest recommendation from Consumer Reports. You can find this item at a lower price point for another model, but why would you NOT purchase the best available, considering the job they do?

So I spent way too many hours trying to figure out what happened. We have several SCO501CN in our home that failed after several years and they worked so well, I wanted to replace each one of them. What we liked was: no false alarms, voice instead of crazy beeps when there is a problem, and interconnected. I ordered five from Amazon (Amazon.com as the seller) and was surprised to get an entirely different model. What was sent was the SCO500 which hardly appears anywhere on the internet. I did find it on First Alert's website however it wasn't clear that it was a voice model, which is what we really liked about the SCO501CN. The packaging also says nothing about voice. There is even a sticker with a bar code that says SCO 501CN on some of them, right below where the packaging clearly indicates that this is the SCO500...so weird. However, I opened one up and low and behold, it was voice, and CO, and smoke and interconnected, exactly what we wanted. It appears that the US has updated their requirements (UL STD 217) for smoke detectors due to the increasing number of lithium battery caused fires, and these models are consistent with this standard. So hopefully the new SCO500 works as well as the SCO501CN and thus far after a few weeks, no false alarms and they all installed easily (and into the same ceiling base as the old ones). Hopefully Amazon will update the listing for this at some point. I was told in November by their customer service that they would however still nothing yet.

I needed to replace the seven First Alert smoke detectors in my house that had reach their end of life. These combo smoke and carbon monoxide detectors are great because they "communicate" with each other via radio frequency. So when one goes off, they all go off in the house. They are also seriously loud. I would wear hearing protection when installing these or testing them. They will wake the dead! They will also announce where the problem is and what type of problem has been encountered. The message will say something like "smoke has been detected in the basement" on all of them even though the smoke was only found in the basement. Setting them up was pretty straight-forward, except the instructions could have been laid out a bit better. They were hidden under all of the regulatory and safety hogwash that they have to put in these directions. You just need to set up one and then link all the rest to the first one. You can also program a location for each one, so that they will announce were smoke or CO has been detected. (Hint: If you are setting up multiple detectors at once, put a piece of masking tape on the detector with the name that you gave it. Once you installed the detector in the proper place, you can remove the tape.) Hopefully, I will not experience the false alarms that others have encountered. If I do, I will update this review.

If you install more than one, all detectors will trigger and alert you to where the smoke/carbon monoxide is present based on which detector noticed the issue first. So, if you have a detector in the living room and that detector is the first to trigger, all of your other detectors will trigger telling you that the living room detector has been activated and whether it's smoke or carbon monoxide. And, they are loud! I actually have 2 detectors in my apartment, and my sister lives downstairs from me in a different apartment, so I installed a detector there as well. If her detector is triggered I am notified, and if one of my detectors is triggered she is notified as all detectors were programmed by me to trigger each other. And the programming is easy. This adds an extra layer of security and comfort for both my sister and I.