Many people mistakenly think that there is a place in your home that everyone agrees on that the detector should go. In reality, there are very few federal regulations, and most manufacturers of CO detectors give contradicting instructions on where to place them. Some people also say “CO is heavier than air, so it sinks”, when in reality CO is almost the same weight as air, so it neither sinks nor rises, but goes with the natural stack affect of the home.
So where should it go? Fist of all, somewhere within about 10-15 foot of combustibles is a good start – i.e. your heating unit, water heater, fireplace (burning wood creates CO as well). Then ideally one should be placed in all the bedrooms and in the basement stairwell. When it comes to CO detectors, more is better