Best CO Detectors

Top-rated carbon monoxide detectors

Kidde carbon monoxide detectors are mentioned most often in reviews, and models that have a digital readout are preferred. The Kidde KN-COPP-3 (*Est. $45) is hardwired, with a digital readout and peak-level indicator. While such units are reliable, several experts recommend choosing a battery-powered model because people tend to use carbon monoxide-producing measures (such as fireplaces and space heaters) during power outages, when the other type of model wouldn't work. To eliminate this problem, the KN-COPP-3 is supplemented with a nine-volt battery backup for continuous operation, even in a power outage. It gets very good ratings from expert reviewers, and most owners at Amazon.com say it is reliable. A few people had trouble with some units that drained the backup batteries too quickly, but this updated model doesn't appear to have that problem. This model is also sold as the Kidde 900-0076.

The Kidde KN-COPP-B (*Est. $40) is battery operated -- it doesn't plug in at all. While that makes it very easy to place (because you don't need to be near an outlet), you'll need to be diligent about replacing batteries as needed. The unit does come with a low-battery indicator. It also has a digital readout and peak-level memory, along with a test/reset button. Owners of these Kidde models posting reviews on Amazon.com are generally pleased with their performance and ease of use. Most experts say that CO detectors only last for two to three years, five years at the most. Therefore, if you have a detector that is five years old or older, it's definitely time to replace it. This detector is also sold as the Kidde 900-0146.

Digital readouts on carbon monoxide alarms are important for a couple of reasons. First, they allow you to monitor CO levels and make some determinations about what circumstances might raise the level in your home. Secondly, a digital readout lets you know the unit is powered on and working. Although you can find some less-expensive CO detectors without a digital readout, reviewers greatly prefer models that display CO levels over those that don't. Experts also recommend selecting a digital display with backlight so that the level is easier to read. Furthermore, the cost savings difference between such basic models and the Kidde carbon monoxide detectors in the ConsumerSearch Best Reviewed section is only about $15.

If you don't care about a digital readout, the Kidde KN-COB-B (*Est. $25) is a basic battery-operated model. This carbon monoxide alarm is UL listed, has a test button to ascertain whether the unit is powered, and comes with a five-year warranty. It is also sold as the Kidde 9CO5.

Several combination carbon monoxide and smoke detectors are available, including the Kidde KN-COSM-IB hardwire version (*Est. $45) (also known as the 900-0114) and the KN-COSM-B battery-operated model (*Est. $40) (also known as the 900-0102), both rated highly in reviews. These carbon monoxide detectors have a voice warning system that announces a fire, carbon monoxide, or a low battery -- a nice feature when the alarm wakes you during the night so you know exactly what the alarm is for. The drawbacks include the lack of a digital display and the inclusion of only an ionization-only fire sensor (which detects flames but not smoky fires). Unlike models that also include a photoelectric sensor (for smoke), this model does not offer complete fire protection. In addition, experts say that most fire detectors should work fine for about 10 years, while carbon monoxide detectors should be replaced after no more than five years. That means that for the best protection, you would need to replace this Kidde combo model no less than every five years, even though the fire detector still has useful life left.

TTI (recently merged with KWJ Engineering Inc.) manufactures the Pocket CO 300 (*est. $140), which is designed to be used by pilots, travelers and homeowners to detect CO levels in any environment This keychain-sized, portable carbon monoxide alarm has a digital display, data storage and a control chip to sound an audio alarm. AviationConsumer.com reviewed this detector and considers it a top value.

Experts point out that the test buttons on carbon monoxide alarms test only the electrical circuitry, and not the chemical sensor that detects carbon monoxide itself. We found good reviews of a product made by Aprilaire called Detectagas or Carbon Monoxide Detector Test Kit (est. $18 plus shipping). This is compressed carbon monoxide gas in an aerosol can, which comes with a plastic bag and seals. You spray a small amount of the carbon monoxide gas into the bag after sealing it around the detector, and the alarm should sound within 15 minutes. The amount of carbon monoxide used for the test is not harmful. You should also test the circuitry monthly and change backup batteries at least every six months. A good reminder is to change batteries when you change your clock back and forth for daylight savings.