Carbon monoxide alarms should be installed on every level of the home and in sleeping areas.
More is better! If you only have one CO alarm, you should put it in the hallway outside of the bedrooms. You are most vulnerable when you're sleeping, and you need to be able to hear the alarm if it sounds.
Place all alarms at least 15 feet away from fuel-burning appliances, and make sure nothing is covering or obstructing the unit.
Learn about industry experts' recommendations for home placement.