Kinds of Smoke Alarms
Smoke alarms should be installed on every level of the home, to include the basement, outside each sleeping area and inside every bedroom and rooms where sleeping could occur, such as dens. Smoke alarms should be interconnected so that if one sounds, they all sound. If your home is older, you can install these with a wireless smoke alarm system, available at most retailers.
There are two types of smoke alarms-ionization and photoelectric. The ionization alarm is more responsive to fires that flare, such as cooking fires. A photoelectric alarm is more responsive to smoldering type fires such as a smoldering fire in a trash can, or overheated wiring.
Test your smoke alarms monthly by pushing the test button. If the alarm chirps, it usually means the battery needs to be replaced. Change the batteries yearly, and even if your alarms are hard wired, they still use batteries for backup and should have the batteries replaced as well. All smoke alarms should be replaced every ten years, even if they still respond to the test properly. All smoke alarms have a ten year life cycle and are to be replaced after ten years.