Since March 31, 2006 a state law went into effect requiring homeowners to install carbon monoxide detectors in every residential unit and property in Massachusetts. Understandably, there seems to be a great deal of confusion on the ideal placement of these detectors, since they shouldn't be too close to carbon monoxidee producing sources, such as a gas stove, water heater, fireplace, etc. I have been personally told by a Fireman that I should install a minimum of one detector on each floor of a property, (including the basement and attic), with a detector needing to be installed within 10 feet of each bedroom and not within 20 feet of a kitchen stove. While this information is something that I personally received and followed, it would be wise to contact your local fire department on what they would recommend.