When selling your home in Livermore or Pleasanton California, the law states that all properties must comply with the state fire marshalls mandate of having the correct and operating devices in the home.
To Clarify:
Here are the current requirements as of August 2020.
Each bedroom must have a Carbon dioxide detector (CO2). They can be hardwired or battery operated. They should be placed on the wall above the door no closer to the ceiling than 6 inches and no further away than 10 inches. In addition a CO2 detector is required outside “each sleeping area” usually translated as the hallway or area outside the bedrroms, these can be placed on the ceiling.
In addition each home also now needs a carbon monoxide (CO) detector. This is is different from a CO2 detector and senses odorless and invisible carbon monoxide a dangerous byproduct of combustion.
If you own a 2 story property you need 2 of these detectors one on each level and they can be placed anywhere. Certain detectors are combo units and can detect both. These are ideal but usually cost a little more.
CO2 detectors can be purchased for @ $20 and CO detectors for @$30 at any hardware store, Lowes, Home Depot or Amazon.