In this colder weather it seems like everyone’s carbon monoxide detector malfunctions. It’s true that furnaces run more and houses are closed up more in winter which means the likelihood of carbon monoxide is greater. If your carbon monoxide alarm is going off you should certainly leave the house and call 911. There is a good chance that you activation is due to a malfunction. There are a lot of reasons those malfunctions.
The life of a carbon monoxide detector has increased from 2 years when they were first introduced to up to ten years for the newest models. Carbon monoxide detectors have an electro chemical cell that reacts in the presence of carbon monoxide. These cells are very accurate, but they also have a limited life span. Since these detectors have a limited lifespan Underwriters Laboratories has required the manufacturers to include an end-of life warning signal. Depending on your detector model it will alarm to tell you it has reached the end of its life between 7 and 10 years. That signal is different from a low battery or actual activation sound. It sure would save a lot of emergency responses if the manufacturers could announce the end of life in a way that tells residents that the detector should be replaced instead of make them think they have a carbon monoxide incident.
Another common cause for smoke and CO detector malfunctions in cold weather is caused by condensation. Many building codes require that alarm system wiring be out in conduit. Many times this conduit goes through an unheated attic space. When warm air from the house is inside the conduit and cold air is on the outside of the conduit condensation forms on the inside of the pipe, just like it forms on the inside of your window. The condensation then runs down the inside of the conduit and drops onto the top of the detector causing it to activate. Condensation will activate smoke alarms and carbon monoxide alarms. In this situation you will see water or water stains on top of the detector. You can usually eliminate this problem by rolling out a blanket of insulation on top of the conduit which will keep it from getting cold.
Another common cause for activation is a low battery. The low battery alarm is a slight chirp instead of an actual alarm. You can see list of the alarm types on the bottom of most detectors. Also on the bottom of the detector will be a date of manufacture. If you detector is over five years old you should consider replacing it. If you do need to replace a detector it is easiest if you can get the exact same detector that will fit into the existing bracket and use the same plug as the old detector.
If your alarm goes off please leave the house and let the fire department make sure everything is alright. Don’t worry about being a bother to the responders, most departments respond in a non-emergency manner to these calls and will not let them interfere with what might be a true emergency.