Smoke alarms mounted to the ceiling are placed at least 4 inches from the wall near the bedroom door. Bedroom alarms are particularly necessary for those who choose to sleep with the door closed and have a television, air conditioner or other appliance in the room. An alarm outside the door in a hallway will suffice for people who sleep with the door open. This alarm will detect smoke quicker from other areas of the home. Some ceilings are higher than the average height and this makes changing batteries inconvenient. Attaching the alarm to the wall is acceptable, but it should be no farther than 12 inches below the ceiling. Keep a distance of at least 3 feet from forced-air registers; blowing air could prevent the alarm from detecting smoke. Three feet should also be allotted if there is a connected bathroom; a blast of hot steam coming from a suddenly open door could trigger the alarm.
Two types of alarms are available for use in the bedroom. The ion is generally less expensive and reacts faster to flames before smoke. The photoelectric alarm reacts quicker to smoldering fires. Either alarm provides protection, but if you're unsure which alarm to use, alternate the alarms throughout your home.
Your bedroom smoke alarm will let you know when the battery needs to be changed. The alarm emits a chirping sound about every 20 seconds. Chirping generally starts in the evening when the battery is weak and there is a drop in temperature. The warning chirp may last as long as a month before the battery dies; this allows you plenty of time to replace the battery. Most alarms use a 9-volt battery and should be changed once a year. Setting a date, such as a birthday, will help you remember to change batteries.
Smoke alarms have a life expectancy of around 10 years. Removing a worn-out alarm in your bedroom is as simple as removing screws and replacing with a new alarm. Mark the date of purchase in an inconspicuous place so you'll know when it needs to be replaced. Alarms are inexpensive and not worth hanging on to once they get to the end of their life.