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Best Smoke Detectors

By: Carl Laron on March 21, 2018

Ionization smoke detectors are best at detecting active flames

Ionization-only smoke detectors are the most common variety in the United States -- making up some 90 percent of the total according to reports. These types of smoke detectors are ideal for detecting fast, active fires and flame particles, making them the best choice for locations where these types of fires are the most common -- such as a kitchen. However, they are less effective in detecting slow, smoldering fires that give off lots of smoke, but little in the way of flames or heat.

The Kidde RF-SM-DC (Est. $35) is a top choice in this category. Also known as the Kidde 0919-9999, the RF-SM-DC has been professionally tested by Consumer Reports. While, like all ionization detectors, it scores poorly in detecting smoldering fires, it's a top performer when it comes to alerting you to flaming ones. User feedback is strong, and it gets good overall scores from owners posting to sites such as Amazon, where it earns a 4.4 star rating based on around 200 reviews. At Home Depot, satisfaction is even higher -- with ratings ranging from 4.6 stars to 4.7 stars, split between three packs and single units of this alarm, and over 335 reviews overall.

Like all smoke alarms, the Kidde RF-SM-DC isn't free of the odd lemon, and we did see a few reports of units that failed prematurely or that were given to hypersensitivity, signaling an alarm with little provocation. However, these reports are minimal compared to those that are satisfied, and low in relation to some other smoke detector models.

The battery powered Kidde RF-SM-DC is wirelessly interconnectable. If any of the connected Kidde RF-SM-DC smoke detectors is triggered, they all will sound the alarm. Owners praise this feature, which can potentially alert you faster to the presence of a fire anywhere in the home; it is said to work well.

The Kidde RF-SM-AC (Est. $60) is similar, but is hard wired. Also known as the Kidde RF-SM-ACDC and the Kidde 1279-9999, one useful application is as a bridge between a pre-existing hard-wired, interconnected smoke alarm network and a new Kidde wireless interconnected network. Simply replace one of the existing hard-wired smoke detectors with the Kidde RF-SM-AC and when a smoke detector on either network sounds, all will sound. The RF-SM-AC includes adapters that will allow this Kidde model to be used with most existing hard-wired smoke detector networks. It's not been tested by any experts we deem to be credible, nor is there a ton of user feedback, but what is available is fairly positive -- including a 4.8 star score based on nearly 50 reviews at Home Depot.

If you live in an area that requires a 10-year sealed battery, the Kidde i9010 (Est. $25) is worth considering. This is a stand-alone, ionization only smoke detector that's been around for a number of years. That may be why user reviews are a little mixed as the overarching complaint among those that are less than completely satisfied is that the smoke detector's battery petered out far sooner than the promised 10 years. Still, its satisfaction ratings are no worse than other cheap ionization smoke detectors that are similar. Examples include 4.1 stars following nearly 400 reviews at Amazon, for example, and a rating of 4.5 stars following more than 320 reviews at Home Depot, where this smoke alarm is sold as the Code One 21010019.

The First Alert 0827B (Est. $30) is another alternative among smoke alarms with 10-year sealed batteries. That smoke alarm replaced the First Alert SA340CN, which had very mixed reviews -- and feedback for the new unit and old one are sometimes intermingled, making it tough to get a read on how the current version actually performs and lasts. Still, what reviews we were able to find that reflect only the 0827B look positive and there's now just enough of them to indicate that performance and longevity will likely be on a par with the Kidde i9010.

Photoelectric smoke detectors ideal for identifying smoldering fires

The sensors in photoelectric smoke alarms respond best to smoky, smoldering fires, which develop slowly and often start in bedding, clothing or upholstery. The First Alert SA511B (Est. $40) is a battery-operated photoelectric smoke alarm with wireless interconnectability. It's not been tested by any expert reviewers we deem to be reliable, but does well with users at most sites.

This is a single unit, and is sold under both the First Alert and BRK brands. It's also available in a two pack as the First Alert SA511CN2-3ST (Est. $70), and that's the version that actually gets the most feedback. For example, at Amazon it earns a score of 4.1 stars following more than 320 reviews. Wirecutter does not test the smoke alarm, and hence its evaluation isn't relied on in making our selection. That said, based on their own research, Doug Mahoney calls the SA511CN2-3ST the best basic smoke alarm. The feedback on the SA511B is even better, albeit more limited: 4.7 stars at Amazon, 4.6 stars at Home Depot, but that's only based on around 20 reviews across the two sites.

Like all photoelectric smoke detectors, it's fair to expect excellent performance in detecting slow, smoldering fires -- such as what might happen if an unextinguished cigarette were to come in contact with upholstered furniture or bedding. However, it will be slower to react to fast, flaming blazes, which might be more common in the case of a kitchen fire.

The First Alert SA521CN-3ST (Est. $40) is a hardwired version of the battery operated First Alert SA511CN2-3ST/SA511B interconnectable smoke detector. The two First Alert smoke detectors can be mixed and matched to create a smoke detector network that covers your premises. If you have a pre-existing interconnected hard-wired smoke detector network, a First Alert SA521CN-3ST (sometimes sold as simply the First Alert SA521CN) can be substituted for one of the existing units to act as a bridge so that when one smoke detector is activated, all smoke detectors on both networks will sound an alarm. This can be an effective way to integrate new, interconnected photoelectric smoke detectors with an existing hard-wired interconnected ionization smoke detector network for protection against all types of fires. The alarms are also compatible with interconnectable First Alert CO and combination smoke and CO alarms, such as the First Alert SCO501CN-3ST (Est. $50), which is covered in our section on combination smoke and CO detectors. Both of these smoke alarms use wireless technology to create their interconnected network. If you already have a wired network in place, the First Alert 7010B (Est. $20) is a photoelectric smoke detector to consider. Also sold under the BRK brand, this smoke detector can be used on the same network with pretty much all current BRK and First Alert interconnectable smoke and CO detectors. You don't get the talking technology found in the pricier First Alert models, but there are latching indicators so you can see which smoke/CO detector in the network initiated the alert.

The 7010B has been tested by Consumer Reports, and is among the highest rated photoelectric-only smoke detectors there. As previously noted, Consumer Reports only recommends dual sensor alarms, and gives this model the highest possible rating for detection smoldering fires, but the lowest grade when it comes to flaming ones -- which is in line with virtually all smoke detectors.

User feedback isn't particularly ample, but what's there is fairly strong. We spotted nearly 70 reviews at Home Depot, and a rating of 4.3 stars. At Lowe's, the smoke alarm earns a rating of 4.5 stars based on more than 50 reviews.

Dual-sensor smoke detectors protect against both types of fires

Consumer Reports says that while any working smoke detector is far better than none at all, the best approach is a combination of smoke detector technologies -- ionization and photoelectric. As a result, dual sensor smoke detectors are the only ones it recommends. Also, some of the best user feedback we spotted was for dual-sensor smoke detectors.

However, that viewpoint is not universal. Though, as noted above, Wirecutter does not test basic smoke detectors, they do conduct research that includes talking to fire experts such as Joseph Keenan, assistant fire marshal in Burlington, Vermont, who says that the better approach is to use separate devices so that each can be placed in locations that are best suited to their type. He also notes that, because ionization smoke detectors are more prone to nuisance alarms, if a homeowner disables the device over that -- which is a very bad idea, by the way -- they lose all protection. Wirecutter also notes that Keenan's comments reflect the official recommendations of the state of Vermont.

Still, if you want the comprehensive protection that a dual-sensor smoke alarm provides, the First Alert 3120B (Est. $35) is an easy recommendation -- though with one caveat. This is a hardwired, interconnectable alarm, which means that, while it's ideal for new construction or as part of a remodeling job, it's more of a hassle for do-it-yourselfers to install unless a compatible hardwired network of First Alert smoke detectors is already in place. However, expert and user feedback indicates that if you can overcome that hurdle, this is the smoke detector to buy.

This dual-sensor alarm, which is sold under both the First Alert and BRK brands, is among the top rated smoke alarms at Consumer Reports. Testing reveals it to be an excellent performer when called on to detect both flaming fires and smoldering ones.

User feedback is just as impressive. Smoke detectors of all types tend to get low marks, especially for their tendency for false alarms. The 3120B is not immune to those types of complaints, but we saw less of them than for most other smoke detectors. At Amazon, it earns a 4.4 star score after more than 400 reviews. While feedback is based on far fewer reviews at other sites, satisfaction is similar elsewhere. For example, it earns a 4.7 star score at Home Depot, where 97 percent of the nearly 50 users who rate it say they would recommend it to a friend.

The Kidde PI2010 (Est. $40) is similar, and performs similarly well in testing by Consumer Reports, again doing an excellent job detecting all types of fires. However, while it is expert recommended, user feedback isn't as ample or as strong. We spotted around 175 reviews at Amazon, and a so-so 3.9 star rating. The biggest issue is the one the plagues many smoke detectors, excessive false alarms. In addition, this model was part of a large recall by Kidde in March 2018 over a manufacturing error that rendered one of the dual sensors inoperable. Free replacement alarms are available for defective units; you can find more information at the Kidde web site.

If your home lacks a hardwired network of interconnected smoke detectors, and tackling the job of wiring a whole house smoke alarm system is too much for your DIY skills (or contractor budget) to allow, stand-alone battery-operated smoke detectors remain a reasonable second choice. Tops among these is the First Alert SA320CN (Est. $20), a dual-sensor, battery-powered smoke detector that earns positive feedback overall. It's been tested by Consumer Reports, and earns the top rating for detecting both smoldering fires and flaming ones, though not a recommendation -- presumably because it cannot be interconnected with other alarms. User reviews are positive, including a 4.6 star rating at Home Depot, and recommendations from 98 percent of the nearly 100 owners that leave reviews.

While most users are very satisfied with the First Alert SA320CN, a minority of those posting at Amazon say that they received smoke detectors that appeared to be defective, or that become so in a shorter than acceptable time frame. Some note that over time, the low-battery warning can begin to sound more frequently, even with fresh batteries.

Kidde makes a near-identical detector, the Kidde PI9010 (Est. $30) , and it scores identically to the First Alert SA320CN in Consumer Reports' testing. Like the First Alert SA320CN, it includes dual ionization/photoelectric sensors to detect both types of typical household fires. However, user feedback is a bit troubling, including 3.4 stars after more than 160 reviews at Amazon. Complaints center on units that either sound excessive false alarms, or that completely fail within a year or two. In addition, it, too, was caught up in the Kidde recall mentioned above.

The ionization/photoelectric-sensor smoke alarms above use standard batteries. However, they are inappropriate for those who live in a state or city that requires that battery-operated smoke detectors be powered by sealed 10-year batteries. In that case, we suggest the First Alert SA3210 (Est. $50). It's very similar to the First Alert SA320CN save for the power source -- a sealed 10-year lithium battery that complies with regulations in those areas that require them. It's not been professionally reviewed, but the handful of user reviews we spotted scattered on sites across the internet have largely been positive thus far. For example, though the totals are lumped in with the First Alert SA320CN at Amazon, all but 4 of the more than 30 that weigh in on the SA3210 specifically grant it either 4 stars or 5.

Combination smoke and CO alarms provide convenience

While experts have different recommendations on where to install smoke detectors and CO alarms (see our report on CO detectors to learn more about where these should be placed for maximum effectiveness), there are many instances where having both in close proximity is recommended for complete safety -- for example in common areas, such as hallways that are adjacent to bedrooms. For those situations, opting for a combination smoke and carbon monoxide detector can save money and reduce clutter.

Among combination smoke and carbon monoxide alarms, the First Alert SCO501CN-3ST (Est. $50) looks like a top choice. Like the First Alert SA511CN2-3ST discussed in the section on photoelectric smoke alarms, the SCO501CN-3ST uses radio technology to set up a wireless network with other First Alert interconnectable alarms -- smoke, CO or combination -- without the complications that a hardwired interconnected alarm system would entail, though you might need to experiment a little with alarm location to make sure that each unit is within range of at least one other interconnected alarm.

The SCO501CN-3ST includes a few other noteworthy extras as well. This is a "talking" alarm, and you can program all of your alarms to relay exactly which of the interconnected units is sounding an alert. The built-in smoke detector uses photoelectric technology.

Reviews of the First Alert SCO501CN-3ST are mostly strong. It receives a recommendation from Consumer Reports for its performance as a CO detector, but only a middling rating as a smoke detector as it only has photoelectric sensors for that function (once again, Consumer Reports only recommends smoke detectors with both types of sensors, though not all experts agree that those types of alarms are the best option). Still, the SC501CN's performance earns the highest possible grade both when it comes to smoldering fires, and as a CO detector. It receives top ratings across the board for detecting high concentrations of CO, low concentrations of CO and the quality of its alerts.

Most owners seem pleased and, while complaints about false alarms are not unheard of, we don't see as many as what's typically seen with battery operated smoke detectors. At Amazon, we spotted more than 275 reviews and a 4.2 star rating. At Lowe's, there's less feedback -- just over 30 reviews -- but a 4.5 star rating and recommendations from 90 percent of owners.

The Kidde KN-COSM-BA (Est. $35) is also worth considering. This combination smoke and CO alarm has been around for a number of years, and was previously known as the Kidde KN-COSM-B. It has two key differences compared to the SCO501CN-3ST: It is a stand-alone detector that does not communicate with other alarms and the smoke detector uses ionization, not photoelectric technology. It has a voice annunciator that will identify the type of hazard (fire or CO), but can't relay that to other detectors. It's not been professionally reviewed, but there's a large body of mostly satisfied users that post feedback at Amazon, where its overall score is 4.4 stars following around 1,750 reviews.

The Kidde KN-COSM-IBA (Est. $40), previously known (and sometimes still available) as the Kidde KN-COSM-IB, is the hardwired version of the Kidde KN-COSM-BA -- but one with a significant difference: It can interconnect with up to 24 Kidde alarms (plus an additional six sounding devices). However, it relies on a hardwired connection to do so, so unless you have an existing network of Kidde alarms, it's best for new construction or a major renovation project. Like the KN-COSM-BA, it has a voice alert to announce whether the hazard is smoke or carbon monoxide, but that and location information is not passed to other alarms in the system. It has been professionally reviewed by Consumer Reports as both a CO detector and a smoke detector, but with only middling ratings. Users are pretty pleased, however, though some complain of false alarms or of receiving the wrong/different unit compared to the model listed and pictured. At Amazon, it earns a 4.4 star rating following more than 485 reviews.

As is the case with smoke detectors, some states and cities require combination smoke and CO detectors to use a non-replaceable battery with a 10-year lifespan. If that applies to you, the Kidde P3010CU (Est. $55) is a model to consider. It's a stand-alone alarm with voice warnings to signal the nature of the threat. The smoke detector uses a photoelectric sensor. We didn't see any credible expert reviews and user feedback is only so-so -- 3.9 stars based on more than 130 reviews in total split between single units and twin packs at Home Depot, and even worse scores at Amazon, though that's based on fewer than 20 reviews. Unfortunately, we didn't spot any other combination smoke and CO detectors with 10-year batteries with significant feedback and better scores.

Smart combination CO and smoke detectors

Having devices that connect to the Internet is all the rage. Everything from "smart" appliances to thermostats to, yes, combination smoke and CO detectors are now available. Among the latter the best known of these is the second generation Nest Protect (Est. $120). The current generation model is well-rated by technology sites and publications, such as CNET, and is the top rated smart smoke alarm at Wirecutter and Top Ten Reviews, and named the best battery-powered unit by Reviewed.

The Protect's history is a little checkered, however. One of its key features at launch was the ability to silence the alarm with the wave of a hand. Unfortunately, that feature also detected the activity often related to the discovery of the fire -- like running out of the room -- and interpreted it as a command to silence the alarm, compromising effectiveness. The Nest Protect was the subject of a Consumer Product Safety Commission recall over that. It's since returned to market, with the feature removed, and at a lower price.

Like the First Alert SCO501CN-3ST, the Nest Protect is a combination CO detector and photoelectric smoke detector. Its feature lineup includes a night mode that prevents low-battery chirps from disturbing your sleep and a humidity sensor that helps the unit tell the difference between smoke and a steamy shower. It forms a network with other Nest Protect units, and can pass information on regarding the location and nature of a detected hazard. It also can communicate with other Nest products, such as the Nest Learning Thermostat (Est. $230) for example, to turn off your heating system if CO or smoke is detected.

The Nest Protect's other noteworthy feature is its ability to connect to the internet. As long as you are within reach of an internet connection, the Protect can send a message to your cellphone or tablet alerting you of trouble at home. The associated app has features such as setting up a home emergency plan and an overview of events in your home over the last 10 days. The Nest Protect comes in both battery powered and hardwired versions.

In terms of core performance, most reviewers give Nest Protect a thumbs up. It has only a photoelectric sensor, which normally will mean that it is more effective in detecting smoldering fires rather than fast-burning ones -- and that's exactly the performance that Consumer Reports found when it tested the first generation model. However, the current, second generation Nest has a unique Split-Spectrum sensor that's said to be more effective than the norm for photoelectric technology. However, we did not spot any rigorous testing to verify that claim, so for now, consider this to be a standard photoelectric unit. Likewise, expert testing of the CO side of things is limited. No one has rigorously tested the CO detector performance of the second generation model. Consumer Reports says that the first generation Nest Protect worked well as a CO detector, though it was more effective in sounding an alarm when it spots high CO concentrations than low. User reviews, once mixed, are now much stronger as the product has been updated and tweaked since release. It currently earns a 4.6 star rating following nearly 6,000 reviews at Amazon.

While there are other smart smoke detectors available, none that we spotted have received the positive feedback that we saw for the Nest Protect. For example, the First Alert OneLink (Est. $110) looks to directly compete with the Nest, but both expert and user reviews are underwhelming. Among other issues, both CNET and Wirecutter note shortcomings in the connected features, including slow response times pushing notifications to the iOS (only) app and for the app to silence a nuisance alarm. Reviewers hold hope that software improvements will eventually make the OneLink a contender, but for now, as Wirecutter notes, "many of the Onelink's features are just pale imitations of the Protect's offerings."

We also saw a little expert buzz around the Halo Smart Smoke & CO Alarm (Est. $130), a hardwired smart smoke and CO detector. Most actually review the Halo +, a model that adds weather alerts, and $20, to the regular Halo, but that model is not currently available. Still, core functionality should be the same, and that's well liked by the experts that have seen the unit. It's the top-rated smart smoke detector at Reviewed, the second highest rated model at Top Ten Reviews, and earns a 4 star rating from CNET. User reviews are both limited and uninspiring, though, so we think the Nest is a better bet for most, for now. One plus compared to other smart smoke detectors is that it contains both ionization and photoelectric sensors for detecting all types of fires. One minus is that while this smoke detector can be interconnected with other units to form a network, that network is hardwired. That means that installation can be a challenge unless it is part of a major remodeling job, or in new construction.

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