Reference

A smoke alarm that goes off with no fire is nearly always detecting something real that is not smoke: cooking aerosols, shower steam, dust, an insect in the chamber, or a sensor that has drifted with age. This guide works the causes by symptom, gives the durable fix for each, and covers what NIST found about new alarms.

A chirping smoke alarm is a working alarm asking for maintenance, and the interval between chirps is the diagnosis. This guide decodes every sound a residential smoke or CO alarm makes, from the low-battery chirp to the end-of-life warning no battery will silence, and separates them from the emergency patterns that mean evacuate.