The number of carbon monoxide detectors you need really depends on how many sleeping areas you have in your house (and how many levels too). According to California law, there should be a CO detector installed on each level as well as near EACH sleeping area. For example, if bedrooms are split into two wings in your house, you’ll need two detectors in order to adequately cover each area. Or if there are two separate wings and also an upstairs bedroom, you’d need three detectors because of the three sleeping areas. You get the point, right? Watch the video below where I help you visualize what I’m talking about.
Additionally, Zack Finley of North American Home Services gives some brief background into carbon monoxide in the video below.