What is the Best Location for Carbon-Monoxide Detectors?
A caller wanted to know whether to mount a carbon monoxide (CO) detector high, near the ceiling, or low, near the floor. He was confused because the instructions said to mount it high, but he thought that CO was heavier than air, and would thus tend to pool at low levels. By Bill’s estimation (and that of a later caller), though, he determined that CO gas was lighter by atomic weight than the major constituents of air (Nitrogen and Oxygen), and would indeed rise. Also, Carbon Monoxide expelled by most cases where it would trigger a detector (from a furnace or from a car’s exhaust) would be hot, and thus have even a lower density than the surrounding air. I recently came across a blurb in Today’s Homeowner about standards for CO detectors. According to it, Underwriters Laboratories specified a standard (#2034) describing what exposure levels to allow before detectors sound an alarm. 2034 specified a level that resulted in a large number of false alarms. 2034-95 allows 15 parts per milli
