To test these detectors, we took to the lab and built a test setup designed to measure each unit’s response time to various concentrations of carbon monoxide, specifically at 250 ppm and 400 ppm. Our goal was to determine each detector’s respective effectiveness at detecting potentially dangerous levels of carbon monoxide. In choosing our winners, we also took into account features that contribute to the overall user experience, performance, and cost-effectiveness of each unit.
For the 250 ppm concentration level, we are trying to simulate a situation where carbon monoxide has started to build up to dangerous levels. We test twice at this concentration and average the results. At 400 ppm, we are replicating a worst-case scenario, a potentially deadly situation, and we give the units a pass or fail rating. Spoiler alert: they all save your life, which shows how important it is to have carbon monoxide detectors on every level of your home.
Our custom carbon monoxide detector test station. It’s one of the deadliest things we’ve ever put together in our product testing lab.
This is one of the most dangerous tests we have ever performed. Carbon monoxide exposure is no joke. It is virtually undetectable and, well, pretty deadly. We had to come up with a safe way to test carbon monoxide detectors without endangering the health and safety of our lab personnel. So I used my rudimentary carpentry skills and built a carbon monoxide detector testing station. The components are:
Carbon monoxide detector chamber — made of wood, plexiglass, silicone, tape and some finishing nails.
Carbon monoxide tank with gas flow regulator — cylinder tank with carbon monoxide content of 2,500 ppm and residual air.
Testo 300 with carbon monoxide ambient sensor –our control device for this experiment.
Two portable carbon monoxide gas alarms.
A look inside CNET’s carbon monoxide detector test setup.
The chamber houses two carbon monoxide detectors, a) the ambient CO sensor portion of our test instrument, the Testo 300, a combustion analyzer used by heating engineers who carry out installation and routine maintenance of industrial and residential heating systems, and b) the Unit Under Test, or UUT, which takes the place of any carbon monoxide detector we have tested for you. The chamber is sealed with foam, but not airtight, as we are not necessarily interested in making a carbon monoxide bomb.
We use a portable carbon monoxide detector on the gas pressure regulator so we don’t have to worry about leaks.
We have a gas flow regulator installed on our tank to prevent pressure spikes, followed by a gas line to feed our gas mixture into the chamber. Two additional portable carbon monoxide detectors are used. One at the valve to ensure there are no leaks, and another to be worn by the person conducting the experiment to ensure there is no buildup of carbon monoxide in the test station area. Additionally, our breathing suits and well-ventilated location ensure that we have a constant flow of fresh air at all times. This may sound like overkill, but it is always good lab practice to put safety first, especially when dealing with such a stealthy and prolific killer.
We start by introducing our gas mixture into the chamber and closely monitoring the carbon monoxide concentration on the Testo. Once the concentration in our chamber reaches at least 250ppm or 400ppm, we stop introducing the gas and start a timer. We want to assess how long it takes for the carbon monoxide detectors to respond to those conditions. As you can imagine, we wanted to limit our exposure while ensuring that our results were repeatable.
Our results are summarized in the interactive chart below:
