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Kidde CO Smoke Alarm

Kidde CO/Smoke Alarm Review

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The Kidde battery-operated Combination CO/Smoke alarm is available as a single unit, or in bundles of three or six pieces, so that you can install an appropriate amount of sensors for the size of your home or rental property.

Being battery operated, it is easy to install and does not require the services of an electrician.  


Overall Score: 4.6/5
  • 10-year life and 5-year limited warranty
  • A voice alarm announces in words whether the activation was due to fire or CO gas, so people in the home know immediately what the problem is. This function also applies to other conditions, including testing.
  • When the alarm is tested, the device will tell you if there has been a previous CO gas detection, so that you know if there is something you need to look out for.
  • Easy installation with batteries only, so you do not need the expense of an electrician.
  • The high concentration and low-level gas warnings are valuable if you have a problem such as a dirty pilot light or fireplace that is not drawing well.
  • This Kidde CO/smoke alarm is an ionization smoke alarm which is typically more effective at detecting fast flaming fires, where a photoelectric smoke alarm is more effective at detecting slow smoldering fires. You must understand the greatest risk you are protecting your property for.


A feature I like very much for a combination smoke and carbon monoxide alarm is that it announces the nature of the detection with the words “Fire!” or “Warning, Carbon Monoxide”.

In an emergency every second is important, and for a lot of people, the first reaction to an alarm is probably either a momentary freeze and mental blank, wondering what is going on, or perhaps thinking it is a false alarm.

The audible feature makes sure you know the nature of the activation straight away.

It has the useful hush mode so that you can temporarily silence it if you burn that microwave popcorn or toast.

The test function of the Kidde alarm will alert you with a warning if carbon monoxide gas has previously been detected.  

This warning means you can be on the lookout for any problems, or even as a reminder that the fireplace might need cleaning or the generator might be due for a service.

How easy is it to use?

Not only does it tell you what the nature of the alarm activation is, whether it has sensed smoke or fire, it also uses the audible words when you test it.

It also has an audible tone alarm, which is a loud 85 dB, which can easily be heard over ambient noise and wake people who are asleep.

The Kidde Smoke/CO detector has green and red LED lights as well as the audible alerts so that you can tell at a glance that it is working and if there is an activation or problem.

How accurate is it?

In addition to testing for high levels of smoke or gas, the Kidde alarm warns of low levels of gas over a prolonged period when in test mode. It will tell you if there has been a previous gas detection in a concentration of 100 ppm or higher.

Being an ionization alarm it is better at detecting fast flaming fires than slow smoldering fires.

How easy is it to install?

The Kidde 21026043 comes with comprehensive instructions, including a user guide and manual.

The documentation tells you, not only how to install it, but also where you should mount it and where it should not go.

This information will ensure you don’t install an alarm in the wrong place, where it will be less effective.

It comes with a mounting bracket, screws, drywall anchors; and there are batteries included.

It has another feature which I like, which is that it will mount in 4 different positions, i.e. every 90 degrees, so you don’t have that annoying time up on a chair or ladder, trying to work out which way to turn it so it can click onto the mounting bracket.