A carbon monoxide alarm should be installed on each level of the home that has bedrooms or sleeping areas. They should also be in each bedroom or within 15 feet outside of each bedroom door. In multi-family buildings, an alarm is required in any enclosed common area that is connected by a door, ductwork, or ventilation shaft to a carbon monoxide source. The placement of the alarm should be in a location specified in the manufacturer's instructions. Depending on the model, this may be the wall, ceiling, or other location, such as a plug-in receptacle. You need to avoid locations that are in turbulent air, such as near ceiling fans, heat vents, air conditioners, or open windows. You should also avoid kitchens, garages, and furnace rooms, as installation in these areas could cause nuisance alarms. Alarms should be placed more than five feet from fuel-fired appliances. Also avoid locations that are dusty, dirty or greasy; these substances can contaminate or coat the alarm's sensor, causing the unit to malfunction.