To install and maintain smoke detectors:

Install at least one smoke detector on each level of your house. Best locations are in hallways
and just outside bedroom doors.
As an added safety measure, install two types of smoke detectors. The photoelectric cell variety
detects smoldering fires. and the ionization type detects hot, flaming fires.
Check for a UL (Underwriters Laboratory) emblem on the label to be sure the detectors you
buy meet industry standards. And make sure they each come with a warranty, in case they're
defective.
Affix detectors on the ceiling or high on an interior wall, because smoke and heat rise.
Once a month, check the detectors to make sure the batteries still work. Most detectors have a
test button. If you push the button and hear a beep, the batteries are good. If you hear a chirping
sound, the batteries need to be replaced. (To be safe, you should replace the batteries annually,
whether the malfunction signal goes off or not. To help you remember, choose an annual holiday,
like New Year's Day, as replacement time.)
To make sure the sensing chamber works, you should also test the device with a lit match or candle.
Be sure the alarm rings loudly enough to alert your family.
Most smoke detectors last three to five years. Replace as needed.