To conserve energy, the screen of the CO detector will not light up if no CO is detected. It is important to regularly test the product to ensure proper functionality. Please note that the CO concentration will only be displayed on the screen when it reaches over 30ppm. CO concentrations below 30ppm are generally considered safe and do not pose immediate harm to human beings. The response time of the CO detector varies based on the CO concentration levels. The higher the CO concentration, the faster the alarm response time. Here are the response times for CO detectors: US Standard: 70ppm: 60-240 minutes 150ppm: 10-50 minutes 400ppm: 4-15 minutes EU Standard: 50ppm: over 60-90 minutes 100ppm: over 10-40 minutes 300ppm: over 0-3 minutes

1.Please understand that our CO detector does not support the detection of carbon dioxide. No matter what the CO2 concentration in the house is, our device will only show 0ppm.  2.Please contact our customer service if you are sure that carbon monoxide is not detected.

Ideally, a carbon monoxide alarm should be installed in every room containing a fuel-burning appliance,and one in everybedroom.  However, if the number of carbon monoxide alarms available is limited, the following guidelines should be considered whenchoosing the best places to install an alarm(s): 1.If there is an appliance in a bedroom,a CO monitor should be installed.  2.Install an alarm in rooms containing a flueless or open-flued appliance.  3.Install an alarm where residents spend most of their time.  4. In a studio apartment, a CO alarm should be placed as far away from the cooking appliances as possible, but close to wherethe person sleeps. 5.If the appliance is in a room not normally used (such as a boiler room), the CO alarm should be placed just outside of thisroom so that the alarm can be heard more easily. For more information, please refer to the user manual.

Gas primarily consists of 50% hydrogen, 35% methane, 10% carbon monoxide, and 5% ethylene. In the case of gas leakage alone, the concentration of carbon monoxide may be relatively low and might not be sufficient to trigger the alarm. Only when the gas is not completely burned will a significant amount of carbon monoxide be produced.  Please note that the alarm will only be triggered when the concentration of carbon monoxide in the air reaches the alarm threshold. If the carbon monoxide concentration is below the alarm threshold, the alarm is typically not activated.